Period Of Infection Research Articles

Sex differences in the impact of lower respiratory tract infections on older adults’ health trajectories: a population-based cohort study

BackgroundLower respiratory tract infections (LRTIs) are a major global health concern, particularly among older adults, who have an increased risk of poorer health outcomes that persist beyond the acute infectious episode. We aimed to investigate the mid-term (up to 7 years) and long-term (up to 12 years) effects of LRTIs on the objective health status trajectories of older adults, while also considering potential sex differences.MethodsCohort data of adults aged ≥ 60 years from the Swedish National study of Aging and Care in Kungsholmen (SNAC-K) collected between 2001 and 2016 was analyzed. Information on LRTIs was obtained from the Swedish National Patient Register, and objective health status was assessed using the Health Assessment Tool (HAT) which incorporates indicators of mild and severe disability, cognitive and physical functioning, and multimorbidity. The LRTI-exposed and -unexposed participants were matched using propensity score matching based on an expansive list of potential confounders. Mixed linear models were used to analyze the association between LRTIs and changes in HAT scores.ResultsThe study included 2796 participants, 567 of whom were diagnosed with a LRTI. LRTIs were independently associated with an excess annual decline of 0.060 (95% CI: -0.107, -0.013) in the HAT score over a 7-year period. The associations were stronger among males, who experienced an excess annual decline of 0.108 (95% CI: -0.177, -0.039) in up to 7-years follow-up, and 0.097 (95% CI: -0.173, -0.021) in up to 12-years follow-up. The associations were not statistically significant among females in either follow-up period.ConclusionLRTIs, even years after the acute infectious period, seem to have a prolonged negative effect on the health of older adults, particularly among males. Preventative public health measures aimed at decreasing LRTI cases among older adults could help in preserving good health and functioning in old age.

From acute to persistent infection: revealing phylogenomic variations in Salmonella Agona.

Salmonella enterica serovar Agona (S. Agona) has been increasingly recognised as a prominent cause of gastroenteritis. This serovar is a strong biofilm former that can undergo genome rearrangement and enter a viable but non-culturable state whilst remaining metabolically active. Similar strategies are employed by S. Typhi, the cause of typhoid fever, during human infection, which are believed to assist with the transition from acute infection to chronic carriage. Here we report S. Agona's ability to persist in people and examine factors that might be contributing to chronic carriage. A review of 2233 S. Agona isolates from UK infections (2004-2020) and associated carriage was undertaken, in which 1155 had short-read sequencing data available. A subset of 207 isolates was selected from different stages of acute and persistent infections within individual patients. The subset underwent long-read sequencing and genome structure (GS) analysis, as well as phenotyping assays including carbon source utilisation and biofilm formation. Associations between genotypes and phenotypes were investigated to compare acute infections to those which progress to chronic. GS analysis revealed the conserved arrangement GS1.0 in 195 isolates, and 8 additional GSs in 12 isolates. These rearranged isolates were typically associated with early, convalescent carriage (3 weeks- 3 months). We also identified an increase in SNP variation during this period of infection. We believe this increase in genome-scale and SNP variation reflects a population expansion after acute S. Agona infection, potentially reflecting an immune evasion mechanism which enables persistent infection to become established.

Development of a triplex endpoint PCR assay for the detection of SARS-CoV-2: insights on cost-efficiency and method design.

Lower respiratory tract infections, including COVID-19, have a substantial global impact, making the development of diagnostic tests crucial. The study aimed to develop a new, accurate, fast, and cost-effective PCR-based detection method for SARS-CoV-2, applicable in limited settings and capable of detecting all current variants and potential future pathogens. The study was conducted between 2020 and 2022 at the molecular biology department of Mures County Clinical Hospital, Romania. Initially, pharyngeal and nasal secretions were collected and processed using the real-time qRT-PCR method for routine COVID-19 diagnosis. Ninety-two samples were randomly selected to develop the assay, including samples from different infection periods and negative controls. Complementary DNA (cDNA) was prepared from the selected samples, and the presence and integrity of the extracted RNA were evaluated by amplifying the GAPDH housekeeping gene. Primers for three specific viral genes (N, ORF1ab, and S) were designed, and their efficiency was evaluated using endpoint PCR and sequencing. Finally, the method was optimized and implemented as a one-step triplex PCR assay for routine diagnostic use. The molecular laboratory at the Mures County Clinical Hospital (MCCH) analyzed a total of 41,818 samples between June 2020 and December 2022. Among these samples, 26.15% tested positive for SARS-CoV-2, while 70.9% were negative and 2.95% were inconclusive or invalid. Three peaks of positive tests were observed in November 2020, April 2021, and February 2022. The study selected 92 preserved RNA samples for triplex-PCR assay development, validating the primers' specificity and confirming the quality of the nucleic acids. The comparative analysis showed the efficiency and accuracy of the endpoint reverse-transcription triplex-PCR method (RT-PCR), indicating its potential as a cost-effective alternative to real-time reverse-transcription PCR (qRT-PCR) in low-income countries with limited infrastructure for COVID-19 testing. This method has the potential to facilitate large-scale diagnosis of SARS-CoV-2 infections, allowing for rapid and appropriate therapeutic management and ongoing monitoring of patients. Additionally, the method can be easily adapted for the detection of other pathogens.

Improved Protocol for Efficient Agrobacterium-Mediated Transient Gene Expression in Medicago sativa L.

Medicago sativa L. (Alfalfa) is a globally recognized forage legume that has recently gained attention for its high protein content, making it suitable for both human and animal consumption. However, due to its perennial nature and autotetraploid genetics, conventional plant breeding requires a longer timeframe compared to other crops. Therefore, genetic engineering offers a faster route for trait modification and improvement. Here, we describe a protocol for achieving efficient transient gene expression in alfalfa through genetic transformation with the Agrobacterium tumefaciens pCAMBIA1304 vector. This vector contains the reporter genes β-glucuronidase (GUS) and green fluorescent protein (GFP), along with a selectable hygromycin B phosphotransferase gene, all driven by the CaMV 35s promoter. Various transformation parameters—such as different explant types, leaf ages, leaf sizes, wounding types, bacterial concentrations (OD600nm), tissue preculture periods, infection periods, co-cultivation periods, and different concentrations of acetosyringone, silver nitrate, and calcium chloride—were optimized using 3-week-old in vitro-grown plantlets. Results were attained from data based on the semi-quantitative observation of the percentage and number of GUS spots on different days of agro-infection in alfalfa explants. The highest percentage of GUS positivity (76.2%) was observed in 3-week-old, scalpel-wounded, segmented alfalfa leaf explants after 3 days of agro-infection at a bacterial concentration of 0.6, with 2 days of preculture, 30 min of co-cultivation, and the addition of 150 µM acetosyringone, 4 mM calcium chloride, and 75 µM silver nitrate. The transient expression of genes of interest was confirmed via histochemical GUS and GFP assays. The results based on transient reporter gene expression suggest that various factors influence T-DNA delivery in the Agrobacterium-mediated transformation of alfalfa. The improved protocol can be used in stable transformation techniques for alfalfa.

Validation of a risk stratification tool for SARS-CoV-2 Delta community transmission in the Australian Capital Territory.

During the SARS-CoV-2 Delta (B.1.617.2) variant outbreak, from August to October 2021 in the Australian Capital Territory (ACT), the number of new cases 'in the community for part of their infectious period' was publicly reported daily. We describe the stratification tool used during the outbreak to determine presumptive risk of community transmission from cases, and present the results of a contemporaneous validation of each case's risk against their onward transmission detected by routine surveillance. After case interview, epidemiologists identified the most likely source of infection for each new case and used the stratification tool to classify the case as either no, low, or high risk of community transmission. Each case notified between 12 August and 14 September 2021 was matched to its recipient case(s) to determine how well the tool predicted transmission risk. Household transmissions were excluded. Of the 530 notified cases stratified, 159 (29.3%) were cases who transmitted to a recipient case. Of the 59 cases who were the source of community transmission, 66% (38/59) were undertaking high-risk activities not associated with permitted essential work at the time. Only six source cases stratified as low risk or no risk transmitted SARS-CoV-2 to those outside their own household. The tool was essential in the rapid determination of community transmission risk in the ACT, and validation of the tool against detected onward transmission provided evidence for the effectiveness of public health restrictions. In the early stages of outbreaks of diseases for which transmissibility has not yet been established, the validation of such a stratification tool relies on high quality case investigation data, but may help to understand transmission dynamics and to inform interventions.

Determinants of unsuccessful tuberculosis treatment outcome in Southwest Ethiopia regional state public hospitals, 2022: a multi-center case control study

BackgroundTuberculosis is the major cause of morbidity, and it is one of the top ten causes of death globally. In Africa, the overall pooled estimate of unsuccessful tuberculosis treatment outcome was reported to be 21.1%, which is above the World Health Organization defined threshold of 15%. Unsuccessful treatment outcomes result in drug resistance, prolonged periods of infection, and increased morbidity and mortality. Therefore, this study aimed to assess determinants of unsuccessful treatment outcomes among tuberculosis patients in Southwest Ethiopia regional state public hospitals, in 2022.MethodA retrospective unmatched case–control study was employed by recruiting 570 study units (190 cases and 380 controls) in three randomly selected public hospitals from 1 August 2022 to 21 August 2022. Data were collected by using a data extraction checklist adapted from tuberculosis registration logbook. Bivariate and multivariate logistic regression models were employed. A predictor variable with a p-value of less than 0.05 in the multivariate logistic regression model was taken as statistically significant. The odds ratio and 95% confidence level were used to measure the strength of the association.ResultA total of 561 records (187 cases and 374 controls) were included from tuberculosis registers. In this study, the factors independently associated with unsuccessful tuberculosis treatment outcome were older age (AOR = 1.68, 95% CI: 1.142, 2.472), rural residence (AOR = 1.548, 95% CI: 1.055, 2.272), retreatment category (AOR = 2.12, 95% CI: 1.339, 3.357), underweight (BMI < 18.5 kg/m2) (AOR = 1.952, 95% CI: 1.240, 3.071), being HIV positive (AOR = 2.144, 95% CI: 1.372, 3.349) and having no treatment adherence support (AOR = 2.016, 95% CI: 1.270, 3.201).Conclusion and recommendationIn this study, socio-demographic, clinical, and treatment-related factors contributed to the risk of unsuccessful treatment outcomes. Targeted interventions should be taken into consideration to diminish poor tuberculosis treatment outcomes among high-risk groups throughout the whole tuberculosis treatment course.

Candidemia in Pediatric-Clinic: Frequency of Occurrence, Candida Species, Antifungal Susceptibilities, and Effects on Mortality (2020-2024).

Objective: Invasive candidiasis is defined as an important infection that increases the duration of patients' hospital stay, costs, mortality and morbidity. In this study, we aimed to investigate the frequency of candidiasis in blood cultures of pediatric hematology patients, Candida species, antifungal susceptibilities, and their effects on mortality. Materials and Methods: Patients with Candida growth in their blood cultures at follow-up in the pediatric hematology clinic of our hospital between 2020 and 2024 were included in the study. Age, gender, primary diseases and risk levels, subtypes and antifungal susceptibilities of Candida grown in blood cultures, the presence of neutropenia in patients, the antifungals used for prophylaxis and treatment, the duration of infection, other bacteria grown additionally during the fungal infection period, the local infection source and the patients' discharge status were obtained from medical records. These constituted the study data. Results: Blood cultures were requested for 594 patients from the Pediatric hematology Clinic, and Candida was grown in only 37 (6.7%) of them. A total of 43.2% of them were the Candida parapsilosis complex, 29.7% were Candida albicans and 8.1% were the Candida haemulonii complex. Antifungal susceptibilities were over 90% for anidulafungin, micafungin, caspofungin, posaconazole, itraconazole and amphotericin B, followed by 86.7% for fluconazole and 84.4% for voriconazole. The mean age of the patient group was 6.8 years, 50.5% of whom were female and 40.5% of whom were male. The Candida infections developed on the 12.1th day of the neutropenia process on average. The mean invasive Candida infection period was 7 days. A total of 18.9% had a second bacterial infection and 13.5% had a local infection. A total of 51.4% had a single antifungal, 18.9% had two antifungals and 2.1% had more than two antifungals. A total of 35.1% of the patients with invasive candidiasis died. The primary diagnosis of the disease, Patient risk level, and the female gender were important factors affetting mortality. Conclusions: In a pediatric hematology clinic, the non-albicans group in invasive candidiasis infections was notable, with the C. parapsilosis complex occurring most frequently. There was still a high sensitivity to echinocandin antifungals and a decreased sensitivity to triazoles. It was found that the factor of the clinical diagnosis, being in the high-risk group and being female had significant effects on the survival rate of patients with candidiasis infections.

MAVS signaling shapes microglia responses to neurotropic virus infection

Viral encephalitis is characterized by a series of immunological reactions that can control virus infection in the brain, but dysregulated responses may cause excessive inflammation and brain damage. Microglia are brain-resident myeloid cells that are specialized in surveilling the local CNS environment and in case of viral brain infection they contribute to the control of the infection and to restriction of viral dissemination. Here, we report that after exposure to neurotropic vesicular stomatitis virus (VSV), murine in vitro microglia cultures showed rapid upregulation of a broad range of pro-inflammatory and antiviral genes, which were stably expressed over the entire 8 h infection period. Additionally, a set of immunomodulatory genes was upregulated between 6 and 8 h post infection. In microglia cultures, the induction of several immune response pathways including cytokine responses was dependent on mitochondrial antiviral-signaling protein (MAVS). Consequently, in Mavs-deficient microglia the control of virus propagation failed as indicated by augmented virus titers and the accumulation of viral transcripts. Thus, in the analyzed in vitro system, MAVS signaling is critically required to achieve full microglia activation and to mediate profound antiviral effects. In Mavs-deficient mice, intranasal VSV instillation caused higher disease severity than in WT mice and virus dissemination was noticed beyond the olfactory bulb. Virus spread to inner regions of the olfactory bulb, i.e., the granular cell layer, correlated with the recruitment of highly inflammatory non-microglia myeloid cells into the olfactory bulb in Mavs−/− mice. Furthermore, increased cytokine levels were detected in the nasal cavity, the olfactory bulb and in other brain regions. Thus, microglial MAVS signaling is critically needed for virus sensing, full microglia activation, and for orchestration of protective immunity in the virus-infected CNS.

Weather conditions and legionellosis: a nationwide case-crossover study among Medicare recipients.

Legionellosis is a respiratory infection caused by Legionella sp. that is found in water and soil. Infection may cause pneumonia (Legionnaires' Disease) and a milder form (Pontiac Fever). Legionella colonizes water systems and results in exposure by inhalation of aerosolized bacteria. The incubation period ranges from 2 to 14 days. Precipitation and humidity may be associated with increased risk. We used Medicare records from 1999 to 2020 to identify hospitalizations for legionellosis. Precipitation, temperature, and relative humidity were obtained from the PRISM Climate Group for the zip code of residence. We used a time-stratified bi-directional case-crossover design with lags of 20 days. Data were analyzed using conditional logistic regression and distributed lag non-linear models. A total of 37883 hospitalizations were identified. Precipitation and relative humidity at lags 8 through 13 days were associated with an increased risk of legionellosis. The strongest association was precipitation at day 10 lag (OR = 1.08, 95% CI = 1.05-1.11 per 1 cm). Over 20 days, 3 cm of precipitation increased the odds of legionellosis over four times. The association was strongest in the Northeast and Midwest and during summer and fall. Precipitation and humidity were associated with hospitalization among Medicare recipients for legionellosis at lags consistent with the incubation period for infection.

Numerical simulation on exhaled aerosol transmission based on realistic oral-nasal structures and temperature distribution

ABSTRACT Respiratory infections are currently understood to be caused by pathogens released through the nose or mouth of an infected individual, and subsequently transmitted to susceptible hosts. These pathogens are enclosed in liquid particles that are aerosolized from the respiratory tract during activities such as breathing, speaking, sneezing, and coughing. These particles vary widely in size, ranging from submicron to several microns. While past research has largely overlooked the human respiratory system, recent analysis has revealed that the actual structure of the nasal cavity significantly influences the prediction of aerosol transmission during exhalation. In this study, computational fluid dynamics (CFD) simulations were conducted to analyze the aerosol transmission generated during exhalation from the nasal and oral cavities. Realistic nasal and oral cavity structures were taken into account, and authentic temperature distributions were applied to the surfaces. Additionally, inhalation conditions for susceptible individuals were established to evaluate the risk of inhalation-generated exposure. Through various simulation scenarios, we separately discussed the impact of environmental wind speed, separation distance, and exhalation flow rate. The simulation results indicate that environmental wind amplifies the complexity of the flow field and the transmission and deposition of particles between two individuals. Under ambient wind velocities of 0.5 m/s and 1 m/s, it was observed that over 80% of the particles with a diameter of 1 µm inhaled through the nasal cavity accounted for the total deposition on the infected individual. Furthermore, high exhalation flow rates exhibited higher deposition ratios at close distances, in line with our expectations. Therefore, it is advisable to minimize close contact as much as possible during periods of frequent respiratory infections, and to wear masks in order to reduce the risk of inhalation exposure. Implications: During the activities such as breathing, speaking, sneezing, and coughing, liquid particles containing pathogens are aerosolized from the respiratory tract and are released from nose or mouth through the nebulization. In this study, we investigated the transmission of aerosols from human exhalation in the outdoor environment, innovatively taking the real oral-nasal structure and the active inhalation of vulnerable people into consideration, and explored the human-to-human transmission of respiratory viruses. The results are beneficial for public health assessment and policy development.

SARS-CoV-2 Vaccination in Patients with Cancer and COVID-19 in Mexico

Objectives: Vaccination is the best preventive measure for SARS-CoV-2 infection; however, efficacy is lower in cancer patients. During the pandemic period, Mexico was characterized by the use of seven different COVID-19 vaccine platforms, and oncologic patients were not prioritized for vaccination. We report the outcomes of COVID-19 in cancer patients after the beginning of the national vaccine campaign in Mexico. Methods: All patients with cancer and COVID-19 diagnosed at Instituto Nacional de Cancerología from 14 February 2021 to 28 February 2022 were included. Primary outcomes were the proportion of individuals who required hospital admission and/or invasive mechanical ventilation, according to the vaccination status; 30-day mortality; the period of infection; and other cancer-related variables. Results: A total of 691 patients were included; 524 (76%) had solid tumors (STs), and 167 (24%) had hematologic malignancies (HMs). Patients infected in the first two periods, had lower rates of vaccination and higher rates of mortality and hospitalization compared to those infected in the Omicron period. In the multivariate analysis, vaccination status was independently associated with hospitalization in patients with STs (aOR 0.38, 95%CI 0.19–0.75, p = 0.005), but it was not associated with invasive mechanical ventilation and 30-day mortality. In those with HMs, vaccination status was not associated with any outcome; in this group, only recent chemotherapy and time of infection were associated with invasive ventilation. Conclusions: Vaccination significantly reduced hospital admissions in patients with STs. Infections occurring during the Omicron period were associated with improved outcomes in both ST and HM patients. Despite having a lesser impact in immunosuppressed patients, vaccination is an essential strategy, and access to vaccination campaigns in patients with cancer needs to be prioritized.

Overcoming bias in estimating epidemiological parameters with realistic history-dependent disease spread dynamics

Epidemiological parameters such as the reproduction number, latent period, and infectious period provide crucial information about the spread of infectious diseases and directly inform intervention strategies. These parameters have generally been estimated by mathematical models that involve an unrealistic assumption of history-independent dynamics for simplicity. This assumes that the chance of becoming infectious during the latent period or recovering during the infectious period remains constant, whereas in reality, these chances vary over time. Here, we find that conventional approaches with this assumption cause serious bias in epidemiological parameter estimation. To address this bias, we developed a Bayesian inference method by adopting more realistic history-dependent disease dynamics. Our method more accurately and precisely estimates the reproduction number than the conventional approaches solely from confirmed cases data, which are easy to obtain through testing. It also revealed how the infectious period distribution changed throughout the COVID-19 pandemic during 2020 in South Korea. We also provide a user-friendly package, IONISE, that automates this method.

Effects of cowpea aphid-borne mosaic virus infection on the growth and yield parameters of Sesamum indicum plants

The potyvirus cowpea aphid-borne mosaic virus (CABMV) is the main viral agent present in crops of Sesamum indicum in several regions of Paraguay. However, information about the effects of CABMV infection in S. indicum plants is scarce and the critical period for virus infection in S. indicum plants is unknown. This study aimed to evaluate the damage caused by CABMV on the development and yield of S. indicum plants experimentally infected at three phenological stages. Mechanical inoculations of CABMV were performed on S. indicum plants at the early vegetative stage, at the beginning of flowering, and during capsule and seed formation. An enzyme-linked immunosorbent Assay (ELISA) test was used to confirm virus infection on the inoculated plants using specific CABMV antisera. Plants inoculated 30 days after emergence (DAE) had severe systemic symptoms, but they were mild in mid and late-infected plants (60 and 90 DAE). Plant aerial dry weight was significantly affected by CABMV infection, reducing up to 71.6% compared to the control. Mid and late-infected plants experienced a lower level of damage, with an average aerial dry weight reduction of 17 and 14.2%, respectively. Furthermore, plants with early, mid, and late CABMV infections showed an average capsule per plant reduction of 97, 33.3, and 13.3%, compared to healthy plants. Seeds per capsule produced by CABMV-infected plants decreased by 93.5%, 21%, and zero, respectively. Viral infections also affected the 1000-seed weight in early infected plants, with a reduction of up to 93.3%. To prevent economic losses, it is crucial to have effective strategies for managing CABMV, particularly during the early stages of the crop.

The optimal spatially-dependent control measures to effectively and economically eliminate emerging infectious diseases.

Non-pharmaceutical interventions (NPIs) are effective in mitigating infections during the early stages of an infectious disease outbreak. However, these measures incur significant economic and livelihood costs. To address this, we developed an optimal control framework aimed at identifying strategies that minimize such costs while ensuring full control of a cross-regional outbreak of emerging infectious diseases. Our approach uses a spatial SEIR model with interventions for the epidemic process, and incorporates population flow in a gravity model dependent on gross domestic product (GDP) and geographical distance. We applied this framework to identify an optimal control strategy for the COVID-19 outbreak caused by the Delta variant in Xi'an City, Shaanxi, China, between December 2021 and January 2022. The model was parameterized by fitting it to daily case data from each district of Xi'an City. Our findings indicate that an increase in the basic reproduction number, the latent period or the infectious period leads to a prolonged outbreak and a larger final size. This indicates that diseases with greater transmissibility are more challenging and costly to control, and so it is important for governments to quickly identify cases and implement control strategies. Indeed, the optimal control strategy we identified suggests that more costly control measures should be implemented as soon as they are deemed necessary. Our results demonstrate that optimal control regimes exhibit spatial, economic, and population heterogeneity. More populated and economically developed regions require a robust regular surveillance mechanism to ensure timely detection and control of imported infections. Regions with higher GDP tend to experience larger-scale epidemics and, consequently, require higher control costs. Notably, our proposed optimal strategy significantly reduced costs compared to the actual expenditures for the Xi'an outbreak.

8241 Post-Covid complications in patients with diabetes mellitus are high during 24 month after acute infection

Abstract Disclosure: A. Alieva: None. The consequences of coronavirus infection in patients with diabetes have not been fully studied. The purpose of the work was to study post-Covid complications in patients with diabetes. Materials and methods. We examined 188 patients with diabetes mellitus who had a coronavirus infection in 2020 and applied to the RSSPMCE clinic for inpatient treatment within 1-24 months after the acute period of viral infection. The criteria for inclusion in the study were: the presence of type 2 diabetes mellitus (DM), diagnosed before 2020, a history of COVID-19 infection confirmed by PCR. Exclusion criteria were pregnancy and diabetes diagnosed in 2020 and later. Results and discussion. An increase in D-dimer levels was observed at 0-3, 7-9 and 19-24 months, which was accompanied by an increase in von Willebrand factor at 4-9 months and thrombosis at 4-6 months after COVID-19. The period of 4-6 months after coronavirus infection was also characterized by an increase in inflammatory markers and the development of purulent complications. The progression of polyneuropathy was noted during the first 6 months after COVID-19; for periods of 6-12 months, the development of vasculitis was typical. In the periods of 1-3 months and 10-24 months after COVID-19, cases of the development of newly registered hypertension were observed. Conclusion. Patients with type 2 diabetes mellitus for 2 years after coronavirus infection remain at risk of developing thrombotic complications, new-onset arterial hypertension and accelerated progression of chronic complications of diabetes mellitus, which requires careful targeted monitoring of such patients. Presentation: 6/3/2024

Why aphid virus retention needs more attention: Modelling aphid behaviour and virus manipulation in non-persistent plant virus transmission.

Plant viruses threaten food security and are often transmitted by insect vectors. Non-persistently transmitted (NPT) plant viruses are transmitted almost exclusively by aphids. Because virions attach to the aphid's stylet (mouthparts) and are acquired and inoculated via brief epidermal probes, the aphid-virus interaction is highly transient, with a very short aphid virus retention time. Many NPT viruses manipulate their host plant's phenotype to change aphid behaviour to optimise virus transmission. Epidemiological models of this have overlooked a key feature of aphid NPT virus retention: probing or feeding on a plant causes aphids to lose the virus. Furthermore, experimental studies suggest aphids could possibly inoculate multiple healthy plants within one infective period if they do not feed. Consequences of this for virus manipulation of host plant phenotype have not been explored. Our new compartmental epidemiological model includes both behaviour-based aphid dispersal and infectivity loss rates, and the ability of infective aphids to probe multiple plants before virus loss. We use our model to explore how NPT virus-induced host phenotypes affect epidemic outcomes, comparing these results to representative previous models. We find that previous models behave fundamentally differently and underestimate the benefit of an 'attract-and-deter' phenotype, where the virus induces increased aphid attraction to infected plants but deters them from prolonged feeding. Our results also highlight the importance of characterising NPT virus retention upon the aphid during probing. Allowing for multiple infective probes increases disease incidence and the effectiveness of virus manipulation, with implications for epidemic prediction and control.

Establishment of Genetic Transformation System in Lilium pumilum and Functional Analysis of LpNAC6 on Abiotic Stress

Lilium pumilum is widely distributed in northeast Asia. It exhibits strong resistance and possesses high ornamental value. However, it currently lacks an efficient and stable transformation system. Therefore, we aimed to establish an effective genetic transformation system using the Agrobacterium-mediated method for L. pumilum, enabling gene transfer into the plant for gene function research and genetic engineering breeding. Our genetic transformation system achieved a maximum transformation efficiency of 7.25% under specific conditions: a kanamycin (Kana) concentration of 120mg/L, 3 days of pre-cultivation, an A. tumefaciens concentration of 0.7 OD600, an acetosyringone (AS) concentration of 20mg/L, and a 15-minute infection period. We investigated the function of the LpNAC6 from L. pumilum by observing phenotypic and physiological changes under stresses induced by salt, alkali, and drought. Furthermore, overexpression of LpNAC6 resulted in enhanced stress tolerance as evidenced by increased levels of SOD, POD, CAT enzymes, improved photosynthetic indices, and elevated chlorophyll contents; as well as reduced levels of MDA and reactive oxygen species (ROS). These findings demonstrate that we have successfully established a transgenic transformation method for L. pumilum while also providing essential information for cultivating stress-tolerant Lilium species and advancing our understanding of the functions of LpNAC6 in plants.

Analysis of re-infection cases and influencing factors post first severe COVID-19 wave in Jiangsu Province, China

Introduction: This study aimed to assess COVID-19 re-infection rates among individuals previously infected between 2020 and November 2022, particularly during the first wave of high-intensity transmission, and to identify the risk factors associated with re-infection in Jiangsu Province, China. Methodology: Epidemiological investigations were conducted through telephone interviews and face-to-face visits in February and March 2023. Statistical analyses included the Chi-square or Fisher`s exact test for categorical data, Student’s t-test for numerical data, Poisson regression for influencing factors, and Kaplan–Meier for cumulative re-infection risk. Results: Among 12,910 individuals surveyed, 957 (7.4%) cases of re-infection were identified. Re-infection rates varied significantly by initial infection period: 42.5% in January–February 2020, 15.5% in July–August 2021, 6.7% in March–April 2022, and 1.1% in September–October 2022. Females and individuals aged 18–50 years were more susceptible to re-infection. A reduced risk of re-infection was observed in those who received four vaccine doses, with a relative risk of 0.25 (p = 0.019). Conclusions: For populations prone to COVID-19 re-infections, particularly females and young adults aged 18–50 years, receiving four or more vaccine doses effectively reduces the likelihood of repeated infections. These findings emphasize the need to prioritize vaccination and protect high-risk groups in COVID-19 prevention efforts.

Evaluation of the use of additional capabilities of immunochemiluminescent analysis for determining the duration of infection with human immunodeficiency virus

Early assessment of HIV incidence is an important public health tool for understanding the state of the epidemic in a particular area, identifying high-risk groups, and assessing the effectiveness of HIV prevention interventions.Objective. To assess the possibility of using the positivity rate (S/CO) in the HIV Ag/Ab immunoassay on the Alinity i analytical platform to determine the duration of infection during HIV screening.Materials and methods. The study included 316 HIV-infected patients with different infection durations. Immunochemical analysis was performed on an Alinity i automatic analyzer (Abbott Laboratories, USA) using the Alinity i HIV Ag/Ab Reagent Kit (Abbott Laboratories, Germany) in accordance with the manufacturer’s instructions.Results. Statistical analysis of 316 blood samples from HIV-infected patients at different stages of infection demonstrated the reactivity of the Alinity i HIV Ag/Ab test result and a dynamic increase in the positivity ratio during the first six months after the onset of the disease. Based on the data obtained, a threshold value (≤294 conventional units) was obtained for the positivity ratio, which allowed for a clear distinction between HIV-positive patients with a recent (<6 months) period of infection. At the same time, the sensitivity and specificity indicators for detecting recent infection in the CMIA analysis were 79,0% and 63,2%, respectively.Conclusion. The additional usage of the positivity ratio in the Alinity i HIV Ag/Ab CMIA analysis meets the acceptability criteria for assessing the duration of HIV infection and can be a useful tool for analyzing the stage of the epidemic in a particular territory.

A Comparison of the Cecal Microbiota between the Infection and Recovery Periods in Chickens with Different Susceptibilities to Eimeria tenella.

To investigate the effect of Eimeria tenella (E. tenella) infection on the cecal microbiota, resistant and susceptible families were screened out based on the coccidiosis resistance evaluation indexes after E. tenella infection. Subsequently, a comparative analysis of cecal microorganisms among control, resistant, and susceptible groups as well as between different periods following the E. tenella challenge was conducted using metagenomic sequencing technology. The results showed that the abundance of opportunistic pathogens, such as Pantoea, Sporomusa, and Pasteurella in the susceptible group and Helicobacter and Sutterella in the resistant group, was significantly higher on day 27 post-inoculation (PI) (the recovery period) than on day 5 PI (the infection period). Additionally, the abundance of Alistipes, Butyricicoccus, and Eubacterium in the susceptible group and Coprococcus, Roseburia, Butyricicoccus, and Lactobacillus in the resistant group showed a significant upward trend during the infection period compared with that in the recovery period. On day 5 PI, the abundance of Faecalibacterium and Lactobacillus was decreased in both the resistant and susceptible groups when compared with that in the control group and was greater in the resistant group than in the susceptible group, while Alistipes in the susceptible group had a relatively higher abundance than that in other groups. A total of 49 biomarker taxa were identified using the linear discriminant analysis (LDA) effect size (LEfSe) method. Of these, the relative abundance of Lactobacillus aviarius, Lactobacillus salivarius, Roseburia, and Ruminococcus gauvreauii was increased in the resistant group, while Bacteroides_sp__AGMB03916, Fusobacterium_mortiferum, Alistipes_sp__An31A, and Alistipes_sp__Marseille_P5061 were enriched in the susceptible group. On day 27 PI, LDA scores identified 43 biomarkers, among which the relative abundance of Elusimicrobium_sp__An273 and Desulfovibrio_sp__An276 was increased in the resistant group, while that of Bacteroides_sp__43_108, Chlamydiia, Chlamydiales, and Sutterella_sp__AM11 39 was augmented in the susceptible group. Our results indicated that E. tenella infection affects the structure of the cecal microbiota during both the challenge and recovery periods. These findings will enhance the understanding of the effects of changes in the cecal microbiota on chickens after coccidia infection and provide a reference for further research on the mechanisms underlying how the intestinal microbiota influence the growth and health of chickens.