Low Viral Load Research Articles

Digital microfluidics with distance-based detection - a new approach for nucleic acid diagnostics.

There is great enthusiasm for using loop-mediated isothermal amplification (LAMP) in point-of-care nucleic acid amplification tests (POC NAATs), as an alternative to PCR. While isothermal amplification techniques like LAMP eliminate the need for rapid temperature cycling in a portable format, these systems are still plagued by requirements for dedicated optical detection apparatus for analysis and manual off-chip sample processing. Here, we developed a new microfluidic system for LAMP-based POC NAATs to address these limitations. The new system combines digital microfluidics (DMF) with distance-based detection (DBD) for direct signal readout. This is the first report of the use of (i) LAMP or (ii) DMF with DBD - thus, we describe a number of characterization steps taken to determine optimal combinations of reagents, materials, and processes for reliable operation. For example, DBD was found to be quite sensitive to background signals from low molecular weight LAMP products; thus, a Capto™ adhere bead-based clean-up procedure was developed to isolate the desirable high-molecular-weight products for analysis. The new method was validated by application to detection of SARS-CoV-2 in saliva. The method was able to distinguish between saliva containing no virus, saliva containing a low viral load (104 genome copies per mL), and saliva containing a high viral load (108 copies per mL), all in an automated system that does not require detection apparatus for analysis. We propose that the combination of DMF with distance-based detection may be a powerful one for implementing a variety of POC NAATs or for other applications in the future.

Management of cytomegalovirus reactivation in patient with immunotherapy-induced gastritis.

We present the case of a 52-year-old woman diagnosed with stage IV clear cell renal cell carcinoma who received combination of surgery and systemic therapy with nivolumab (anti-PD1) and ipilimumab (anti-CTLA-4). During treatment, patient presented oral intolerance, vomiting and abdominal pain. Computed tomography (CT) and gastroscopy (EGD) were performed, identifying findings suggestive of severe gastro-duodenitis with friability and diffuse oedema of the mucosa and deep ulcers. A gastrointestinal immunotherapy-induced toxicity was suspected so patient was managed with proton pump inhibitors (PPIs) and intravenous corticosteroids 1mg/Kg. Three weeks later, corticosteroid treatment failed. EGD was repeated and gastric biopsies were taken for histological and microbiological tests. Gastric biopsies revealed the presence of cytomegalovirus (CMV) inclusion bodies by immunohistochemistry (IHC). CMV viral load by quantitative PCR in plasma was 2,000 IU/mL so intravenous ganciclovir was prescribed. Then, the patient presented poor clinical course with persistent vomiting due to a failure of first-line corticosteroid and antiviral treatment. Another EGD was performed. Last IHC reveals a low CMV viral load. Second-line treatment with Anti-TNF was performed using a single-dose regimen of intravenous infliximab 5 mg/Kg. Finally, the patient presented a clinical and endoscopic response and a negative CMV DNA test in the blood after completing the antiviral treatment.

Real-world trough concentrations and effectiveness of long-acting cabotegravir and rilpivirine: a multicenter prospective observational study in Switzerland

The efficacy and tolerability of long-acting cabotegravir and rilpivirine were demonstrated in Phase III trials. However, low concentrations combined with other risk factors have been associated with an increased risk of virologic failure. This study aims to verify whether drug concentrations measured in a real-world setting are consistent with those previously reported. SHCS-879 is a nationwide observational study within the Swiss HIV Cohort Study for the monitoring of people with HIV (PWH) on long-acting cabotegravir plus rilpivirine. Samples were collected from March 2022 to March2023. Overall, 725 samples were obtained from 186 PWH. Our data show a large inter-individual variability in cabotegravir and rilpivirine concentrations, with some individuals exhibiting repeatedly low concentrations. Rilpivirine trough concentrations were consistent with those from Phase III trials, while cabotegravir concentrations were lower. The first concentrations quartile was only slightly above the target of 664ng/mL. Exploratory statistical analyses found 35% (p<0·01) lower cabotegravir trough in males compared to females. Overall, 172 PWH (92%) remained suppressed and three experienced virologic failures (1·6%), of those, two had sub-optimal drug exposure. No association was found between low trough levels and detectable viral load. Real-world cabotegravir concentrations are substantially lower than previously reported. However, these concentrations appear sufficient to ensure sustained virological suppression in almost every PWH. These reassuring data challenge the rather conservative thresholds adopted to date, which may raise unnecessary concerns. Yet, our study reveals that some PWH have repeatedly very low drug levels, for reasons that remain to be elucidated. This work was funded by the Swiss National Science Foundation, grant number N◦ 324730_192449. This study received no support from pharmaceutical industries. This study was performed within the framework of the Swiss HIV Cohort Study, supported by the Swiss National Science Foundation (grant #201369), by SHCS project #879, and by the SHCS research foundation. The SHCS data were gathered by the Five Swiss University Hospitals, two Cantonal Hospitals, 15 affiliated hospitals and 36 private physicians (listed in http://www.shcs.ch/180-health-care-providers).

Comparison of Computed Tomography and Clinical Features Between Patients Infected with the SARS-CoV-2 Omicron Variant and the Original Strain.

To investigate potential differences in clinical and computed tomography (CT) features between patients with the SARS-CoV-2 Omicron variant and the original strain. This retrospective study included 69 hospitalized patients infected with Omicron variant from November to December 2022, and 96 hospitalized patients infected with the original strain from February to March 2020 in Chongqing, China. The clinical features, CT manifestations, degrees of lung involvement in different stages on CT, and imaging changes after the reverse-transcription polymerase chain reaction (RT-PCR) results turned negative were compared between the two groups. For clinical features, patients with Omicron were predominantly old people and females, without manifestation of any clinical symptoms, who had low serum levels of C-reactive protein and procalcitonin. Shorter interval from symptoms onset to initial CT scan was observed in Omicron patients compared to patients with the original strain (all P < 0.05). For CT features, patients with Omicron were more likely to present with round-like opacities and tree-in-bud pattern (all P < 0.05), but less likely to exhibit a diffuse distribution, patchy and linear opacities, as well as vascular enlargement pattern (all P < 0.05). The Omicron group was more susceptible to exhibiting lower CT involvement scores in each stage (all P < 0.05) and imaging progression after the RT-PCR results turned negative (P < 0.001). Patients infected with the Omicron variant exhibited less severe changes on chest CT compared to those infected with the original strain. Furthermore, imaging progression under low viral load conditions was more common in patients with Omicron than in those with the original strain.

DNA-directed formation of plasmonic core-satellite nanostructures for quantification of hepatitis C viral RNA.

Hepatitis C virus (HCV) continues to be a significant public health challenge, affecting an estimated 71 million people globally and posing risks of severe liver diseases. Despite advancements in treatments, diagnostic limitations hinder the global elimination efforts targeted by 2030. This study introduces an innovative diagnostic approach, integrating catalytic hairpin assembly (CHA) with plasmonic core-satellite gold nanoparticle (AuNP) assemblies, to enable sensitive and specific detection of HCV RNA. We optimized the stoichiometry of DNA hairpins to form highly stable three-way junctions (3WJs), minimizing non-specific reactions in an enzyme-free, isothermal amplification process. The resulting dual-transduction biosensor combines colorimetric and surface-enhanced Raman spectroscopy (SERS) techniques, utilizing the Raman reporter malachite green isothiocyanate (MGITC) for signal generation. Our system targets a conserved 23-nucleotide sequence within the HCV 5'-UTR, essential for RNA replication, facilitating pan-genotypic HCV detection that complements direct-acting antiviral strategies. We evaluated the biosensor's efficacy using fluorescence spectroscopy, native PAGE, AFM, and TEM. Findings indicate that the 60 nm core AuNPs surrounded by 20 nm satellite AuNPs achieved a ten-fold increase in sensitivity over the 10 nm satellites, detecting HCV RNA concentrations as low as 1.706 fM. This sensitivity is crucial, given the extremely low viral loads present during early infection stages. Our research demonstrates the promise of enzyme-free molecular biosensors for HCV, with the potential to provide cost-efficient, rapid, point-of-care testing, although further sensitivity enhancements are needed to address the challenges of early-stage detection.

The rollout of paediatric dolutegravir and virological outcomes among children living with HIV in Mozambique.

In 2022, Mozambique introduced Dolutegravir 10mg (pDTG), as part of paediatric antiretroviral therapy for children weighing < 20 kg. Understanding real-world challenges during national rollout can strengthen health systems in resource-limited settings. We described the transition rate to, and new initiation of, pDTG, viral load suppression (VLS) post-pDTG, and factors associated with VLS among children living with HIV. We conducted a retrospective cohort study involving children aged < 9 years and abstracted data from clinical sources. We used logistic regression to assess VLS and pDTG initiation predictors. Of 1353 children, 1146 initiated pDTG; 196 (14.5%) had no recorded weight. Post-pDTG switch, 98.9% (950/961) of children maintained the same nucleoside reverse transcriptase inhibitor backbone. After initiating Abacavir/Lamivudine+pDTG, 834 (72.8%) children remained on the regimen, 156 (13.6%) switched off (majority to Dolutegravir 50mg), 22 (1.9%) had ≥ 2 anchor drug switches; 134 (11.7%) had no documented follow-up regimen. Factors associated with pDTG initiation or switch were younger age (adjusted odds ratio [AOR] = 0.71 [0.63-0.80]) and a recorded weight (AOR = 55.58 [33.88-91.18]). VLS among the 294 children with a viral load (VL) test after ≥ 5 months post-pDTG was 75.5% (n = 222/294). Pre-pDTG VLS rate among treatment-experienced children was 56.5% (n = 130/230). Factors associated with VLS were older age (AOR = 1.18 [1.03-1.34]) and previous VLS (AOR = 2.27 [1.27-4.06]). Most eligible children initiated pDTG per guidelines, improving post-pDTG VLS. Challenges included unexplained switches off pDTG after initiation, low VL coverage and inadequate documentation in clinic records.

HIF-1-mediated regulation of LDH gene unravels key insights into MCDV-1 pathogenesis in mud crabs Scylla paramamosain

Hypoxia-inducible factors −1 (HIF-1) is a crucial transcription factor that regulates the expression of glycolytic genes. Our previous study proved that the Mud crab dicistrovirus-1 (MCDV-1) can induce aerobic glycolysis that favors viral replication in mud crab Scylla paramamosain. However, the role of HIF-1 on key glycolytic genes during the MCDV-1 infection has not been examined. In this study, the intricate interplay between HIF-1 and the key glycolysis enzyme, lactate dehydrogenase (LDH), was investigated after MCDV-1 infection. The expression of LDH was significant increased after MCDV-1 infection. Additionally, the expression of HIF-1α was upregulated following MCDV-1 infection, potentially attributed to the downregulation of prolyl hydroxylase domains 2 expression. Subsequent examination of the SpLDH promoter identified the presence of hypoxia response elements (HREs), serving as binding sites for HIF-1α. Intriguingly, experimental evidence demonstrated that SpHIF-1α actively promotes SpLDH transcription through these HREs. To further elucidate the functional significance of SpHIF-1α, targeted silencing was employed, resulting in a substantial reduction in SpLDH expression, activity, and lactate concentrations in MCDV-1-infected mud crabs. Notably, SpHIF-1α-silenced mud crabs exhibited higher survival rates and lower viral loads in hepatopancreas tissues following MCDV-1 infection. These results highlight the critical role of SpHIF-1α in MCDV-1 pathogenesis by regulating LDH gene dynamics, providing valuable insights into the molecular mechanisms underlying the virus-host interaction.

A decision-making model for prediction of a stable disease course in chronic hepatitis B patients

Patients with chronic hepatitis B (CHB) are regularly monitored for HBV DNA and liver enzymes in order to assess disease progression and the need for antiviral therapy. Identifying patients with a stable course of disease can potentially prolong the intervals between visits, withhold unnecessary tests and save money. Accordingly, we aimed to find predictors for a stable disease course in patients with CHB. 579 patients with CHB, who were followed in a tertiary referral center between January 2004–December 2018, were retrospectively analyzed. Patients with low and steady viral load titer (< 2000 IU/ml) and normal ALT levels (< 40 IU/ml) in 6 consecutive clinic encounters were considered to have a stable course of CHB. A stepwise multivariate logistic regression analysis and a decision tree model were used to identify predictors of a stable disease course. Following exclusion of ineligible patients, a total of 220 patients were included in the final analysis. 64/220 patients had a stable disease course. Patients with a stable disease were older (62.99 ± 12.36 Vs. 54.07 ± 13.64, p < 0.001) with a higher percentage of women (53% vs. 38%) and had lower baseline levels of AST, ALT and viral load (VL). In a multivariate analysis, age (OR 0.94, 95% CI 0.91–0.98), baseline ALT (OR 1.06, 95% CI 1.01–1.1) and VL (OR 1.05 95% CI 1.02–1.08), were significantly associated with a stable disease. In a decision tree model, patients 46–67 years old, with baseline VL < 149 IU/mL and ALT < 40 IU/mL had the best probability (91%) for a stable disease course over 4.4 ± 2.2 years. We conclude that integrating patients’ age with baseline VL and ALT can predict a stable disease course in patients with CHB off treatment.

Early administration of tecovirimat shortens the time to mpox clearance in a model of human infection.

Despite use of tecovirimat since the beginning of the 2022 outbreak, few data have been published on its antiviral effect in humans. We here predict tecovirimat efficacy using a unique set of data in nonhuman primates (NHPs) and humans. We analyzed tecovirimat antiviral activity on viral kinetics in NHP to characterize its concentration-effect relationship in vivo. Next, we used a pharmacological model developed in healthy volunteers to project its antiviral efficacy in humans. Finally, a viral dynamic model was applied to characterize mpox kinetics in skin lesions from 54 untreated patients, and we used this modeling framework to predict the impact of tecovirimat on viral clearance in skin lesions. At human-recommended doses, tecovirimat could inhibit viral replication from infected cells by more than 90% after 3 to 5 days of drug administration and achieved over 97% efficacy at drug steady state. With an estimated mpox within-host basic reproduction number, R0, equal to 5.6, tecovirimat could therefore shorten the time to viral clearance if given before viral peak. We predicted that initiating treatment at symptom onset, which on average occurred 2 days before viral peak, could reduce the time to viral clearance by about 6 days. Immediate postexposure prophylaxis could not only reduce time to clearance but also lower peak viral load by more than 1.0 log10 copies/mL and shorten the duration of positive viral culture by about 7 to 10 days. These findings support the early administration of tecovirimat against mpox infection, ideally starting from the infection day as a postexposure prophylaxis.

Targeted solutions to increase dolutegravir coverage, viral load testing coverage, and viral suppression among children living with HIV in Togo: An analysis of routine facility data.

According to UNAIDS, Togo halved AIDS-related deaths among children ages 0-14 from 2010 to 2020. However, available data show low dolutegravir (DTG)-containing antiretroviral therapy (ART) coverage and low viral load suppression (VLS) among children living with HIV (CLHIV). We analyzed routine facility data before and after implementation of root-cause-based solutions for improving DTG coverage, viral load (VL) testing coverage, and VLS among CLHIV. We analyzed routine data for CLHIV ≤14 years from October 2019 through September 2022. We assessed proportion of CLHIV on ART receiving DTG, VL testing coverage (CLHIV on ART with documented VL test result), and VLS (CLHIV with documented VL test result of <1,000 copies among those with test result). From October 2019 to September 2020, 52% were on a DTG-containing regimen, 48% had documented VL test results, and 64% had VLS. Site-level teams conducted a root-cause analysis and designed corresponding solutions implemented beginning October 2020: line listing and contacting eligible CLHIV to start/transition to DTG-containing regimen and collect VL samples; ART adherence support; monthly DTG stock monitoring; tracking pending VL test results through laboratory focal persons; documenting VL test results; and informing caregivers within one week if CLHIV not virally suppressed. Granular data were used to prioritize technical assistance to sites with lowest DTG coverage, VL testing coverage, and VLS. From baseline (October 2019-September 2020) to endline (October 2021-September 2022), increases were observed for DTG coverage (52% to 71%), VL testing coverage (48% to 90%), and VLS (64% to 82%). Age-disaggregated data showed positive trends. Root-cause-based solutions and granular data use increased DTG coverage, resulting in increased VL testing and VLS among CLHIV. These interventions should be scaled and become the national standard of care.

Designing effective U = U communication strategies considering the needs of PLHIV, their partners, and healthcare worker constraints in South African clinics.

We sought to understand the Undetectable = Untransmittable (U = U) communication needs of persons living with HIV (PLHIV) and barriers to U = U communication among healthcare providers (HCPs) in South Africa. We conducted five focus group discussions (FGDs) with HCPs (N = 42) including nurses and counsellors from primary healthcare clinics (PHCs) in the Gauteng and Free State Provinces of South Africa, three FGDs (N = 27) with PLHIV recruited by snowball sampling from civil society organizations, and 27 in-depth interviews (IDIs) with recently diagnosed PLHIV in Johannesburg. IDIs and FGDs were audio recorded, transcribed, translated to English, and analysed thematically. PLHIV were largely unaware and sceptical of U = U as the message appeared to contradict the mainstream HIV prevention clinical guidance. The low viral load (VL) knowledge further reduced confidence in U = U. PLHIV need support and guidance on the best approaches for sharing U = U information and disclosing their VL status to their partners, highlighting the central role of community understanding of U = U and VL to mediate the desired stigma reduction, social acceptance and emotional benefits of U = U for PLHIV. HCPs were uneasy about sharing U = U due to concerns about risk compensation and ART non-adherence and worried about enabling any ensuing HIV transmission. HCPs also need a simple, unambiguous, and consistent narrative for U = U, integrated with other HIV prevention messages. PLHIV and HCPs alike recommended a patient-centred approach to communicating U = U, focusing primarily on attaining viral suppression and emphasizing that condomless sex is only safe during periods of ART adherence. These data highlight the need for simple U = U communication support targeting both HCP and PLHIV. Culturally appropriate communication materials, with training and ongoing mentorship of the clinic staff, are essential to improve patient-centred U = U communication in clinics.

The costs of transgenerational immune priming for homologous and heterologous infections with different serotypes of dengue virus in Aedes aegypti mosquitoes.

The immune system is a network of molecules, signaling pathways, transcription, and effector modulation that controls, mitigates, or eradicates agents that may affect the integrity of the host. In mosquitoes, the innate immune system is highly efficient at combating foreign organisms but has the capacity to tolerate vector-borne diseases. These implications lead to replication, dissemination, and ultimately the transmission of pathogenic organisms when feeding on a host. In recent years, it has been discovered that the innate immune response of mosquitoes can trigger an enhanced immunity response to the stimulus of a previously encountered pathogen. This phenomenon, called immune priming, is characterized by a molecular response that prevents the replication of viruses, parasites, or bacteria in the body. It has been documented that immune priming can be stimulated through homologous organisms or molecules, although it has also been documented that closely related pathogens can generate an enhanced immune response to a second stimulus with a related organism. However, the cost involved in this immune response has not been characterized through the transmission of the immunological experience from parents to offspring by transgenerational immune priming (TGIP) in mosquitoes. Here, we address the impact on the rates of oviposition, hatching, development, and immune response in Aedes aegypti mosquitoes, the mothers of which were stimulated with dengue virus serotypes 2 and/or 4, having found a cost of TGIP on the development time of the progeny of mothers with heterologous infections, with respect to mothers with homologous infections. Our results showed a significant effect on the sex ratio, with females being more abundant than males. We found a decrease in transcripts of the siRNA pathway in daughters of mothers who had been exposed to an immune challenge with DV. Our research demonstrates that there are costs and benefits associated with TGIP in Aedes aegypti mosquitoes exposed to DV. Specifically, priming results in a lower viral load in the offspring of mothers who have previously been infected with the virus. Although some results from tests of two dengue virus serotypes show similarities, such as the percentage of pupae emergence, there are differences in the percentage of adult emergence, indicating differences in TGIP costs even within the same virus with different serotypes. This finding has crucial implications in the context of dengue virus transmission in endemic areas where multiple serotypes circulate simultaneously.

Evaluation of the effect of sample suspension concentration and viral load on the outcome of the rabies tissue culture infection test.

In this study, we examined various brain suspension concentrations and viral loads in Neuro-2a cell cultures using 20 rabies-positive bovine samples. The reproducibility of results varied: 65% showed consistent outcomes across all concentrations, while 35% disagreed in at least one. Viral titers ranged from less than 25 × 101 to 25 × 103.50 TCID50/mL, with 20% below 25 × 101 TCID50/mL. Concentrations between 5% and 20% yielded over 90% agreement in positive results, but at 30%, agreement dropped from 85% to 50%. Cell confluence was successfully maintained at 5%, 10%, and 20%, while concentrations of 30% and above led to confluence loss. Low viral loads also negatively impacted reproducibility. These results suggest that sample concentration has a direct influence on preservation of cell confluence and that low viral loads may influence the reproducibility of the rabies tissue culture infection test (RTCIT).

Rapid antigen test as a screening tool for SARS-CoV-2 infection: Head-to-head comparison with qRT-PCR in Ethiopia

ObjectiveThis study aimed to determine the diagnostic accuracy of the antigen rapid diagnostic test (Ag-RDT) as a screening tool for SARS-CoV-2 infection compared to Quantitative reverse transcription polymerase chain reaction (qRT-PCR). MethodsThis study was conducted at six referral hospitals in Oromia Region, Ethiopia. One thousand seven hundred twenty-one patients who visited the hospitals for various medical conditions were tested with qRT-PCR and/or Ag-RDTs. Qualitative detection of SARS-CoV-2 antigen was performed using the Panbio™ COVID-19 Ag rapid test device. ResultsCompared with qRT-PCR, Ag-RDTs had a sensitivity of 33.3 % (95%CI: 30.9%–35.9 %) and a specificity of 99.3 % (95%CI: 98.8%–99.7 %) to detect active SARS-CoV-2 infection. The area under the receiver operator curve was 0.67 (95%CI: 0.63–0.69). The sensitivity of Ag-RDTs appeared high in patients with shortness of breath (73.3 %) and those presenting with all three symptoms – fever, cough, and dyspnea (71.4 %). In all instances, specificity was more than 98 %. The Ag-RDT positivity rate also correlated well with viral load: 51.7 % in cases with cycle threshold (Ct) < 25 (high viral load) and only 3.4 % when Ct > 25 (low viral load). ConclusionAlthough Ag-RDT for diagnosing SARS-CoV-2 is a good option as a point-of-care screening tool, it has a low sensitivity to detect active infections. Using Panbio™ COVID-19 Ag Rapid test for diagnostic and treatment decisions may lead to a false negative, resulting in patient misdiagnosis, ultimately contributing to disease spread and poor patient outcome.

Genomic characterisation of respiratory syncytial virus: a novel system for whole genome sequencing and full-length G and F gene sequences.

To advance our understanding of respiratory syncytial virus (RSV) impact through genomic surveillance, we describe two PCR-based sequencing systems, (i) RSVAB-WGS for generic whole-genome sequencing and (ii) RSVAB-GF, which targets major viral antigens, G and F, and is used as a complement for challenging cases with low viral load. These methods monitor RSV genetic diversity to inform molecular epidemiology, vaccine effectiveness and treatment strategies, contributing also to the standardisation of surveillance in a new era of vaccines.

Rapid identification of full-length genome and tracing variations of monkeypox virus in clinical specimens based on mNGS and amplicon sequencing

The monkeypox virus (MPXV) has triggered a current outbreak globally. Genome sequencing of MPXV and rapid tracing of genetic variants will benefit disease diagnosis and control. It is a significant challenge but necessary to optimize the strategy and application of rapid full-length genome identification and to track variations of MPXV in clinical specimens with low viral loads, as it is one of the DNA viruses with the largest genome and the most AT-biased, and has a significant number of tandem repeats. Here we evaluated the performance of metagenomic and amplicon sequencing techniques, and three sequencing platforms in MPXV genome sequencing based on multiple clinical specimens of five mpox cases in Chinese mainland. We rapidly identified the full-length genome of MPXV with the assembly of accurate tandem repeats in multiple clinical specimens. Amplicon sequencing enables cost-effective and rapid sequencing of clinical specimens to obtain high-quality MPXV genomes. Third-generation sequencing facilitates the assembly of the terminal tandem repeat regions in the monkeypox virus genome and corrects a common misassembly in published sequences. Besides, several intra-host single nucleotide variations were identified in the first imported mpox case. This study offers an evaluation of various strategies aimed at identifying the complete genome of MPXV in clinical specimens. The findings of this study will significantly enhance the surveillance of MPXV.

SARS-CoV-2 RT-PCR as a universal screening on planned admission in asymptomatic patients

Universal screening for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on admission is reportedly beneficial in preventing nosocomial infections. However, some issues remain, including low positivity rate, cost, and time required for testing. We describe SARS-CoV-2 reverse transcription polymerase chain reaction (PCR) for universal screening in asymptomatic patients on planned admissions. In total, 14,574 patients were included between October 12, 2020, and June 23, 2022. The PCR-positive rate for the period was 0.44 % (64/14,574). The PCR positivity for the epidemic period by strain was 0.28 % (95 % confidence interval [CI] 0.12–0.56 %), 0.16 % (95 % CI 0.05–0.37 %), 0.21 % (95 % CI 0.09–0.41 %), and 0.9 % (95 % CI 0.65–1.2 %) for the wild-type strain, Alpha, Delta, and Omicron variants, respectively. The proportion of Ct values < 30 was higher in the first half of the epidemic (first vs. second, 29.4 % [95 % CI 16.9–44.8 %] vs. 16.7 % [95 % CI 6.0–28.5 %]), whereas that of Ct values ≥ 35 increased significantly in the second half (first vs. second, 32.4 % [95 % CI 19.3–47.8 %] vs. 70.0 % [95 % CI 53.5–83.4 %]). Of all positives, 50 % (32/64) had a coronavirus disease (COVID-19) history before PCR screening, with a median of 28 days (10–105) from COVID-19 onset or positive to PCR screening. PCR screening may help detect positives with high viral loads early in the epidemic for each mutant strain, with an increasing proportion of positives with low viral loads later in the epidemic. PCR testing may be unnecessary for recently diagnosed cases and patients in whom reinfection is unlikely.

Safety, immunogenicity and efficacy of an mRNA-based COVID-19 vaccine, GLB-COV2-043, in preclinical animal models

Several COVID-19 vaccines, some more efficacious than others, are now available and deployed, including multiple mRNA- and viral vector-based vaccines. With the focus on creating cost-effective solutions that can reach the low- and medium- income world, GreenLight Biosciences has developed an mRNA vaccine candidate, GLB-COV2-043, encoding for the full-length SARS-CoV-2 Wuhan wild-type spike protein. In pre-clinical studies in mice, GLB-COV2-043 induced robust antigen-specific binding and virus-neutralizing antibody responses targeting homologous and heterologous SARS-CoV-2 variants and a TH1-biased immune response. Boosting mice with monovalent or bivalent mRNA-LNPs provided rapid recall and long-lasting neutralizing antibody titers, an increase in antibody avidity and breadth that was held over time and generation of antigen-specific memory B- and T- cells. In hamsters, vaccination with GLB-COV2-043 led to lower viral loads, reduced incidence of SARS-CoV-2-related microscopic findings in lungs, and protection against weight loss after heterologous challenge with Omicron BA.1 live virus. Altogether, these data indicate that GLB-COV2-043 mRNA-LNP vaccine candidate elicits robust protective humoral and cellular immune responses and establishes our mRNA-LNP platform for subsequent clinical evaluations.

Immune responses and protective efficacy of American eel (Anguilla rostrata) immunized with a formalin-inactivated vaccine against Anguillid herpesvirus

Anguillid herpesvirus 1 (AngHV), the causative agent of "mucus sloughing and hemorrhagic septicemia disease", causes serious infectious diseases in farmed eel. Among the effective prevention and control strategies, vaccination is one of the most effective approaches. However, no vaccine for AngHV is available. Our study developed a formalin-inactivated AngHV vaccine and evaluated its performance in American eels. Initially, AngHV-FJ, a strain of AngHV, was inactivated completely by 0.1 % formaldehyde, mixed with adjuvant Montanide ISA 763 A VG (763A). Then, vaccines containing different amount of antigen (3 × 106 PFU, 3 × 105 PFU, 3 × 104 PFU, 3 × 103 PFU) were immunized in each American eels. The results showed that the 3 × 105 PFU/fish was the proper dose. The inactivated AngHV vaccine was proven safe for American eels by back intramuscular injection. The results of twice immunization showed that antibody production peaked in the 8th week after the first immunization, and the antibody titer was 1:64,000. Furthermore, the immunized fishes challenged with AngHV (105 PFU/ml immersion) showed a significantly lower incidence rate (33.33 %) than the control group (95.65 %). The survival of the fish in the vaccine group (94.44 %) was significantly higher than the control group (60.87 %). The relative survival rate of the vaccinated group was 85.80 %. Also, vaccine group tissue collected at 7th d post-challenge showed reduced tissue damage and a lower virus load than the control group. The expression of cytokines of IL-1β, IFN-α, IFN-γ, Mx1, RIG-1, and IRF-3, were significantly lower in the vaccine group than the control group at the 7th and 14th d post-challenge. Overall, the formalin-inactivated AngHV vaccine was safe and had immune protective effects against AngHV infection.

HIV Type-1 Genotyping in the Context of the COVID-19 Pandemic: A Critical Tool for Identifying Antiretroviral Drug Resistance and Optimizing Treatment Strategies

Abstract Introduction/Objective The COVID-19 pandemic strained the healthcare system and the WHO recently reported increased rates of antibiotic resistance. Meanwhile, antiretroviral resistance can also lead to treatment failure and disease progression, especially in HIV patients. Here, we investigated the rates of HIV drug resistance (HIVDR) in our HIV population between pre and post-COVID-19 eras. Methods/Case Report The post-COVID-19 era began on 03/11/2020. Patients positive for HIV-1 between 01/2019- 08/2021 were included (total: 94 patients, 46 pre-COVID-19; 48 post-COVID-19). Patients’ charts were reviewed for demographics, laboratory results (including HIV-1 sequencing/genotyping (e.g., Genosure)), clinical presentation and management. Student t-test and Fisher exact test were calculated. Results (if a Case Study enter NA) Most patients were male (70%) and had a mean age of 49 years. 70% of patients had sufficient viral loads in samples reflexed to HIV genotyping. Post-COVID-19 patients harbored lower viral loads (1.8x105 vs. 3.4x105 copies/mL, p=0.05), CD4 counts (174 vs. 196 cells/mcL, p=0.7), CD8 counts (555 vs. 800 cells/mcL, p=0.04), and higher CD4/CD8 ratio (0.312 vs. 0.266, p=0.57). Overall, 20% of patients had HIVDR. Following COVID-19 pandemic, there was a 9% increase in HIVDR, predominantly seen in non-nucleotide reverse transcriptase inhibitors (NNRTI), although insignificant. Specifically, high resistance was documented for drugs Efavirenz (16%), Nevirapine (16%), and Rilpivirine (13%). We observed an increased prevalence of G190A, K101, K103, and E138 mutations conferring resistance to NNRTIs. Changes to therapy were observed in 47.8% (42/88) of total cases, with an increase of 12.5% in patients from post-COVID-19 era. Additionally, changes to therapy were observed more in patients with infectious diseases consultation (16% increase). Conclusion Increasing HIVDR was seen in our patient population post-COVID-19. Continued surveillance is critical to managing HIVDR and improving patient outcomes. The clinical utility of sequencing tests can outweigh the cost if results are appropriately acted upon which may involve the participation of other clinical teams and the antimicrobial stewardship committee.