Pdm09 Virus Research Articles

Serological studies of influenza infection among population in southern region of Kazakhstan during the 2018-2021 epidemic season.

To conduct serological studies of influenza infection rate during an epidemic. The retrospective study was conducted at the Research and Production Centre for Microbiology and Virology, Almaty, Kazakhstan, and comprised data, including blood samples, from patients with symptoms of acute respiratory viral infection, bronchitis and pneumonia during 2018-21 from various healthcare institutions in the Almaty region. Serological tests on blood serums were carried out sing haem agglutination inhibition assay and enzyme-linked immunosorbent assay. Data was analysed using Graph Pad Prism 9. Of the 779 blood samples, 392(50.3%) came from women and 387(49.7%) from men. The overall age range was 0-80 years. Serological analyses using haem agglutination inhibition assay showed the presence of anti-hemagglutinins against pandemic A(H1N1)pdm09 virus in 292(37.5%) samples, influenza A/H3N2 virus in 340(43.6%) and type B virus in 53(6.8%). Antibodies against two subtypes of influenza A virus and type B virus were simultaneously identified in 25(3.2%) cases, whereas against influenza A (H1N1+H3N2) viruses in 69(8.9%). In enzyme-linked immunosorbent assay, antibodies against influenza A/H1N1pdm virus were detected in 108(13.9%) cases, against A/H3N2 virus in 105(13.5%) and type B virus in 65(8.3%). Antibodies simultaneously against two subtypes of influenza A virus were identified in 46(5.9%) of blood serums, and against influenza A and B viruses in 60(7.7%). Co-circulation of influenza A and B viruses was observed, confirming the role of influenza viruses in the epidemic process.

A recent outbreak of human H1N2 infection: correspondence.

A recent outbreak of human H1N2 infection: correspondence.

Interim Estimates of 2022–23 Seasonal Influenza Vaccine Effectiveness — Wisconsin, October 2022–February 2023

In the United States, 2022-23 influenza activity began earlier than usual, increasing in October 2022, and has been associated with high rates of hospitalizations among children* (1). Influenza A(H3N2) represented most influenza viruses detected and subtyped during this period, but A(H1N1)pdm09 viruses cocirculated as well. Most viruses characterized were in the same genetic subclade as and antigenically similar to the viruses included in the 2022-23 Northern Hemisphere influenza vaccine (1,2). Effectiveness of influenza vaccine varies by season, influenza virus subtype, and antigenic match with circulating viruses. This interim report used data from two concurrent studies conducted at Marshfield Clinic Health System (MCHS) in Wisconsin during October 23, 2022-February 10, 2023, to estimate influenza vaccine effectiveness (VE). Overall, VE was 54% against medically attended outpatient acute respiratory illness (ARI) associated with laboratory-confirmed influenza A among patients aged 6 months-64 years. In a community cohort of children and adolescents aged <18 years, VE was 71% against symptomatic laboratory-confirmed influenza A virus infection. These interim analyses indicate that influenza vaccination substantially reduced the risk for medically attended influenza among persons aged <65 years and for symptomatic influenza in children and adolescents. Annual influenza vaccination is the best strategy for preventing influenza and its complications. CDC recommends that health care providers continue to administer annual influenza vaccine to persons aged ≥6 months as long as influenza viruses are circulating (2).

The genetic diversity, replication, and transmission of 2009 pandemic H1N1 viruses in China.

The 2009 pandemic H1N1 influenza A virus (pdm09) continue to evolve, and few studies have systemically analyzed the evolution, replication, and transmission of pmd09 viruses in China. To better understand the evolution and pathogenicity of pdm09 viruses, we systematically analyzed viruses that were confirmed in 2009-2020 in China and characterized their replication and transmission ability. We extensively analyzed the evolution characteristics of pdm/09 in China over the past decades. The replication ability of 6B.1 and 6B.2 lineages on Madin-Darby canine kidney (MDCK) and human lung adenocarcinoma epithelial (A549) cells and their pathogenicity and transmission in guinea pigs were also compared. In total, 3,038 pdm09 viruses belonged to clade 6B.1 (62% of all pdm09 viruses) and clade 6B.2 (4%). Clade 6B.1 pdm09 viruses are the predominant clade, with proportions of 54.1%, 78.9%, 57.2%, 58.6%, 61.7%, 76.3%, and 66.6% in the North, Northeast, East, Central, South, Southwest, and Northeast regions in China, respectively. The isolation proportion of clade 6B.1 pdm/09 viruses was 57.1%, 74.3%, 96.1%, 98.2%, 86.7%, and 78.5% in 2015-2020, respectively. A clear differentiation time point appeared in 2015 before which the evolution trend of pdm09 viruses in China was similar to that in North America but then showed a different trend after that point. To characterize pdm09 viruses in China after 2015, we further analyzed 33 pdm09 viruses isolated in Guangdong in 2016-2017, among which A/ Guangdong/33/2016 and A/Guangdong/184/2016 (184/2016) belonged to clade 6B.2, and the other 31 strains belonged to clade 6B.1. A/Guangdong/887/2017 (887/2017) and A/Guangdong/752/2017 (752/2017) (clade 6B.1), 184/2016 (clade 6B.2) and A/California/04/2009 (CA04) replicated efficiently in MDCK cells and A549 cells, as well as the turbinates of guinea pigs. 184/2016 and CA04 could transmit among guinea pigs through physical contact. Our findings provide novel insights into the evolution, pathogenicity, and transmission of pdm09 virus. The results show that enhancing surveillance of pdm09 viruses and timely evaluation of their virulence are essential.

Characterization of Influenza A(H1N1)pdm09 Viruses Isolated in the 2018-2019 and 2019-2020 Influenza Seasons in Japan.

The influenza A(H1N1)pdm09 virus that emerged in 2009 causes seasonal epidemic worldwide. The virus acquired several amino acid substitutions that were responsible for antigenic drift until the 2018-2019 influenza season. Viruses possessing mutations in the NA and PA proteins that cause reduced susceptibility to NA inhibitors and baloxavir marboxil, respectively, have been detected after antiviral treatment, albeit infrequently. Here, we analyzed HA, NA, and PA sequences derived from A(H1N1)pdm09 viruses that were isolated during the 2018-2019 and 2019-2020 influenza seasons in Japan. We found that A(H1N1)pdm09 viruses possessing the D187A and Q189E substitutions in HA emerged and dominated during the 2019-2020 season; these substitutions in the antigenic site Sb, a high potency neutralizing antibody-eliciting site for humans, changed the antigenicity of A(H1N1)pdm09 viruses. Furthermore, we found that isolates possessing the N156K substitution, which was predicted to affect the antigenicity of A(H1N1)pdm09 virus at the laboratory level, were detected at a frequency of 1.0% in the 2018-2019 season but 10.1% in the 2019-2020 season. These findings indicate that two kinds of antigenically drifted viruses-N156K and D187A/Q189E viruses-co-circulated during the 2019-2020 influenza season in Japan.

Recommended Adult Immunization Schedule, United States, 2023.

Recommended Adult Immunization Schedule, United States, 2023.

Serum 25-Hydroxyvitamin D Was Not Associated with Influenza Virus Infection in Children and Adults in Hong Kong, 2009–201

Background: Some studies have hypothesized that vitamin D may have a role to play in protection against influenza virus infections and illnesses, and that seasonal fluctuation in serum 25-hydroxyvitamin D [25(OH)D] may affect seasonal patterns of influenza virus infections.Objective: We aimed to investigate whether serum 25(OH)D concentrations were associated with the incidence of influenza virus infections and illnesses in children and adults in Hong Kong.Methods: In 2009–2010, 3030 children and adults of all ages from 796 households in Hong Kong were followed up to identify acute respiratory illnesses. Sera from 2694 participants were collected at baseline and after ∼1 mo, 6 mo, and 12 mo. Influenza virus infections were confirmed by reverse transcriptase–polymerase chain reaction performed on nasal and throat swab samples collected during illness episodes. Serologic evidence of influenza virus infection was measured by hemagglutination inhibition assays in unvaccinated participants. The serum 25(OH)D concentrations were measured after collection of all specimens. Each individual’s baseline serum 25(OH)D concentration on 1 January 2010 was predicted by a random-effects linear regression model.Results: We found that, in children and adults who had not received a seasonal influenza vaccine, baseline serum 25(OH)D concentrations (<50 nmol/L compared with ≥50 nmol/L) were not statistically significantly associated with serologic evidence of influenza A(H1N1)pdm09 (RR, 1.18; 95% CI: 0.85, 1.65) or seasonal influenza virus infections [including A(H3N2) and B virus] (RR, 1.13; 95% CI: 0.86, 1.49). In all participants, baseline serum 25(OH)D concentrations were not statistically significantly associated with polymerase chain reaction–confirmed influenza virus infection (RR, 1.15; 95% CI: 0.73, 1.83) and influenza-like illness (RR, 1.18; 95% CI: 0.98, 1.43).Conclusions: These findings indicate that lower serum vitamin D concentrations may not contribute to the seasonality of influenza and are not associated with an increased risk of influenza virus infections in persons of all ages in Hong Kong.

Report on influenza viruses received and tested by the Melbourne WHO Collaborating Centre for Reference and Research on Influenza during 2022.

As part of its role in the World Health Organization's (WHO) Global Influenza Surveillance and Response System (GISRS), the WHO Collaborating Centre for Reference and Research on Influenza in Melbourne received a record total of 12,073 human influenza positive samples during 2022. Viruses were analysed for their antigenic, genetic and antiviral susceptibility properties. Selected viruses were propagated in qualified cells or embryonated hen's eggs for potential use in seasonal influenza virus vaccines. In 2022, influenza A(H3N2) viruses predominated over influenza A(H1N1)pdm09 and B viruses, accounting for 77% of all viruses analysed. The majority of A(H1N1)pdm09, A(H3N2) and influenza B viruses analysed at the Centre were found to be antigenically and genetically similar to the respective WHO recommended vaccine strains for the southern hemisphere in 2022. Of 3,372 samples tested for susceptibility to the neuraminidase inhibitors oseltamivir and zanamivir, two A(H1N1)pdm09 viruses showed highly reduced inhibition against oseltamivir.

Changed epidemiology of narcolepsy before, during, and after the 2009 H1N1 pandemic: a nationwide narcolepsy surveillance network study in mainland China, 1990-2017.

Increased incidence of narcolepsy was reported in children during the 2009 H1N1 pandemic following Pandemrix, a H1N1 flu vaccine. A link with A(H1N1) pdm09 infections remains controversial. Using nationwide surveillance data from China (1990 to 2017), the epidemiology of narcolepsy was analyzed. Individual records of narcolepsy patients were collected from 15 of 42 hospitals across China known to diagnose cases. Incidence was estimated assuming the representativeness of these hospitals. Age-specific incidence, epidemiological and clinical characteristics of patients were evaluated before, during, and after the 2009 H1N1 pandemic. Sensitivity analyses were conducted by including NT1 cases only and excluding the effect of the 2009 H1N1 vaccination. Average annual incidence was 0.79 per 100 000 person-years (PY) from 1990 to 2017 and 1.08 per 100 000 PY from 2003 to 2017. Incidence increased 4.17 (95% CI 4.12, 4.22) and 1.42 (95% CI 1.41, 1.44) fold during and after the 2009 H1N1 pandemic when compared to baseline. These results were robust in sensitivity analyses. Patients with the onset of narcolepsy during the pandemic period were younger (notably in 5-9-year-old strata), and the age shift toward younger children reversed to baseline following the pandemic. Increased incidence of narcolepsy was observed during the 2009 H1N1 pandemic period. This is likely to be associated with the circulation of the wild type A(H1N1)pdm09 virus. This observation should be considered for future influenza pandemic preparedness plans.

Comparative analysis of inflight transmission of SARS-CoV-2, influenza, and SARS-CoV-1.

The aim of this study is to evaluate the infection risk of aircraft passengers seated within and beyond two rows of the index case(s) of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), influenza A(H1N1)pdm09 virus, and SARS-CoV-1. PubMed databases were searched for articles containing information on air travel-related transmission of SARS-CoV-2, influenza A(H1N1)pdm09 virus, and SARS-CoV-1 infections. We performed a meta-analysis of inflight infection data. In the eight flights where the attack rate could be calculated, the inflight SARS-CoV-2 attack rates ranged from 2.6% to 16.1%. The risk ratios of infection for passengers seated within and outside the two rows of the index cases were 5.64 (95% confidence interval (CI):1.94-16.40) in SARS-CoV-2 outbreaks, 4.26 (95% CI:1.08-16.81) in the influenza A(H1N1)pdm09 virus outbreaks, and 1.91 (95% CI:0.80-4.55) in SARS-CoV-1 outbreaks. Furthermore, we found no significant difference between the attack rates of SARS-CoV-2 in flights where the passengers were wearing masks and those where they were not (p=0.22). The spatial distribution of inflight SARS-CoV-2 outbreaks was more similar to that of the influenza A(H1N1)pdm09 virus outbreaks than to that of SARS-CoV-1. Given the high proportion of asymptomatic or pre-symptomatic infection in SARS-CoV-2 transmission, we hypothesised that the proximity transmission, especially short-range airborne route, might play an important role in the inflight SARS-CoV-2 transmission.

Прогноз возможной активизации вирусов ОРВИ/гриппа на территории Республике Казахстан в эпидемический сезон 2023-2024 гг.

About 1 billion cases of seasonal influenza are registered annually in the world, including 3-5 million cases of severe form of the disease. Every year up to 650.000 people die from SARS/influenza. The purpose of the study: to make a forecast of possible activation of SARS/influenza viruses on the territory of the Republic of Kazakhstan in the epidemic season 2023-2024. Methods. The analysis of statistical data of subtypes of the virus type A(H1N1)pdm09 and A(H3N2) for the epidemic season 2022-2023 was carried out. Based on the analysis of the previous season, a forecast of possible activation of SARS/influenza viruses in the territory of the Republic of Kazakhstan in the epidemic season 2023-2024 was made. Results. According to the results of laboratory monitoring of SARS/influenza in the epidemic season of 2022-2023, the circulation of all three types of influenza viruses was noted, but their share in the etiological characteristics of the season was different. Since the beginning of the epidemic season influenza B viruses have been dominant - its share in the structure of positive cases reached maximum values from 40 to 49 weeks, the total share for the epidemic season was 66.2% (n=1613). The activation of influenza A(H1N1)pdm09 viruses was noted in the second half of the epidemic season from week 46, this type of virus accounted for 32.5% (n=792) of positive cases during the epidemic season. The circulation of influenza virus subtype A (H3N2) was noted by isolated cases everywhere, during the epidemic season the proportion of positive cases for them was only 1.3% (n=30). Conclusions. In the upcoming autumn-winter season of 2023-2024 parallel circulation of subtypes of type A(H1N1)pdm09 and A(H3N2) virus with the addition of virus B, and with a higher probability the dominance of influenza A(H1N1)pdm09 virus among other influenza viruses is predicted.

Эпидемиологическая характеристика ОРВИ и гриппа на территории Казахстана в эпидемические сезоны с 2018 по 2022 год

One of the most important medical and socio-economic problems worldwide is the incidence of influenza and acute respiratory viral infections (ARVI). The urgency of the problem is due to their widespread prevalence, economic costs, the high probability of a complicated course and exacerbation of chronic non-communicable diseases, the variability of viruses, and the formation of bacterial-associated respiratory diseases against their background. In recent years, the simultaneous circulation of influenza A(H1N1), A(H3N2) and type B influenza viruses has been observed during the epidemiological season. The COVID-19 pandemic has affected the situation of the incidence of ARVI and influenza in the Kazakhstan. Objective. To assess the epidemic situation in Kazakhstan during the epidemic seasons 2018–2019, 2019–2020, 2020–2021, and 2021–2022 and to identify influenza pathogens circulating among the population. Materials and methods. Epidemiological surveillance for ARVI and influenza in Kazakhstan includes several components. The routine system of registering ARVI cases based on appeal is carried out by organizations providing primary medical care. In 2008, epidemiological surveillance for ARVI and influenza was supplemented with sentinel epidemiological surveillance. Sentinel surveillance for influenza, ARVI, influenza-like illness, and SARS is carried out year-round, and the incidence of influenza in outpatients and inpatients is monitored. Records are kept of all requests for medical care in age groups of 0–4, 5–14, 15–29, 30–64, 65 years and older. During the research, the results of regular monitoring in the surveillance system for influenza, ARVI, influenza-like illness, and SARS in four seasons of ARVI and influenza incidence (epidemic seasons from 2018–2019 to 2021–2022, from 40 weeks of the first year to 20 weeks of the second year) were used. Data on the incidence of ARVI and influenza, the results of laboratory tests of the weekly monitoring of the Reference Laboratory for the Control of Viral Infections of the Scientific and Practical Center for Sanitary and Epidemiological Expertise and Monitoring and 16 regional virological laboratories of branches of the National Center for Expertise, combined into a single Information system "Tracking ARVI/influenza/pneumonia", were taken into account. During the study period, coverage in the Republic of Kazakhstan amounted to 2,408,525 cases of ARVI and influenza, including 93,233 hospitalizations. A total of 39,251 samples were examined for influenza, of which 5,553 PCR tests were positive. Sampling for sequencing is carried out after PCR, while samples with a high concentration of viral RNA (Сt ≤25) are taken. Sequencing methods are used for genotyping of influenza viruses. The research methods also included a molecular genetic study of samples from patients with ARVI and influenza. Results. The highest incidence rates of ARVI and influenza were observed in the epidemic season of 2021–2022, with their maximum levels recorded from the 40th to the 51st week and from the 3rd to the 5th week. In the epidemiological seasons 2018–2019 and 2019–2020, the influenza A(H1N1)pdm09 virus dominated, followed by the influenza A(H3N2) virus and the active circulation of the influenza B virus. In the 2020–2021 epidemiological season, 6,564 PCR studies of samples for the presence of the SARS-CoV-2 virus were conducted in the Republic of Kazakhstan, of which 421 (6%) were positive samples, and in the 2021-2022 epidemiological season – 820 (4%). Conclusion. The results of the analysis show that the circulation of influenza and other ARVI pathogens in the epidemiological season continues to play a leading role in the etiology of respiratory viral infections. Key words: influenza viruses, SARS-CoV-2 virus, influenza, morbidity, ARVI, epidemiological situation

Initial and severe cases of influenza in 2020-2022 and population immunity prior to epidemic season

The purpose of the present work was to evaluate population immunity to influenza and molecular genetic analysis of influenza viruses detected in the Russian Federation over 2020-2022. In this study, 1344 samples of blood serum collected prior to the 2021-2022 flu season in Siberian, Southern, Far Eastern, Volga and Ural Federal Districts were studied. Seropositivity to the A/Victoria/2570/2019 vaccine strain (H1N1) pdm09 was detected in 25% to 31% of samples from the four federal districts, and in 8% of samples from the Far Eastern Federal District. Seropositivity to the A/Cambodia/e0826360/2020 strain (H3N2) was detected in 24% to 37% of the samples. The lowest population immunity was revealed to the influenza B/Washington/02/2019 vaccine strain (Victoria lineage), with &lt; 10% of serum samples reactive to the studied strain. Since March 2020, the worldwide turnover of all seasonal respiratory viruses has sharply decreased, except of rhinoviruses. From March 2020 to June 2021, we have identified six B/Victoria influenza viruses from sporadic cases of influenza. From June 2021 to the end February 2022, the State Research Center “Vector” received 901 samples positive for influenza A(H3N2) virus RNA, two specimens positive for A(H1N1) pdm09 virus RNA, and 17 samples positive for influenza B. All studied A(H3N2) viruses belonged to the 3C.2a1b.2a2 subclade (Bangladesh group). The two verified A(H1N1) pdm09 influenza viruses belonged to the 6B.1A.5a clade. All studied influenza B viruses were assigned to the B/Victoria genetic lineage, and to 1A.3a2 subclade. The genomes of all identified viruses did not contain mutations of the NA gene responsible for drug resistance to neuraminidase inhibitors, or mutations in РA gene responsible for baloxavir resistance. All viruses tested by fluorescence assay were sensitive to oseltamivir and zanamivir. The worldwide frequency of influenza isolates resistant to antineuraminidase drugs does not exceed 1-2% of cases. Hence, oseltamivir and zanamivir provide effective treatment for seasonal influenza.

Analysis of non-bacterial respiratory pathogens in children in Ningbo City from 2019 to 2021

Objective: To investigate the distribution characteristics of respiratory non-bacterial pathogens in children in Ningbo from 2019 to 2021. Methods: A retrospective analysis was performed on 23 733 children with respiratory tract infection who visited the department of pediatrics of Ningbo Women and Children's Hospital from July 2019 to December 2021. There were 13 509 males (56.92%) and 10 224 females (43.08%), with an age range of 1 day to 18 years old. There were 981 cases in the neonatal group (younger than 1 month old), 5 880 cases in the infant group (1 month to younger than 1 year old), 6 552 cases in the toddler group (1 to younger than 3 years old), 7 638 cases in the preschool group (3 to younger than 7 years old), and 2 682 cases in the school-age group (7 to 18 years old). Thirteen respiratory pathogens were detected by multiple polymerase chain reaction (PCR) based on capillary electrophoresis, and SPSS 23.0 software was used for statistical analysis of the results, the count data were expressed as percentages, and the χ2 test was used for comparison between groups. Results: Of the 23 733 specimens, 13 330 were positive for respiratory pathogens, with a total positive rate of 56.17%. The positive rates of human rhinovirus (HRV) 24.05% (5 707/23 733), human respiratory syncytial virus (HRSV) 10.45% (2 480/2 3733) and mycoplasma pneumoniae (Mp) 7.03% (1 668/23 733) were in the first three. The positive rates of pathogens in the male and female children were 57.47% (7 763/13 509) and 54.45% (5 567/10 224), respectively, and the difference was statistically significant (χ2=21.488, P<0.001). The positive rates in the neonatal group, infant group, toddler group, preschool group, and school-age group were 31.80% (312/981), 54.71% (3 217/5 880), 63.23% (4 143/6 552), 59.83% (4 570/7 638), 40.57% (1 088/2 682), respectively, and the difference among the groups was statistically significant (χ2=681.225, P<0.001). The single infection rate was 47.43% (11 256/23 733), the mixed infection rate of two or more pathogens was 8.74% (2 074/23 733), most of which were mixed infections of two pathogens. HRV, HADV, HCOV, Ch disseminated in the whole year. HRSV, HMPV, Boca, HPIV occurred mostly in fall and winter. The positive rates of FluA, FluB, Mp were at a low level after the corona virus disease 2019 (COVID-19) epidemic (2020 and 2021). The positive rates of FluA, H1N1, H3N2, FluB, HADV, Mp in 2020 were significantly lower than in 2019 (P<0.05). The positive rates of HPIV, HRV, HCOV, Ch in 2020 were significantly higher than in 2019 (P<0.05). The positive rates of FluA, H1N1, H3N2, HPIV, HCOV, Mp, Ch in 2021 were significantly lower than in 2020 (P<0.05). The positive rates of Boca, HMPV, HRSV in 2021 were significantly higher than in 2020 (P<0.05). Conclusion: From 2019 to 2021, the main non-bacterial respiratory pathogens of children in Ningbo City were Mp and HRV, and the detection rates of respiratory pathogens varied among different ages, seasons and genders.

Adaptive evolution of PB1 from influenza A(H1N1)pdm09 virus towards an enhanced fitness

PB1 influenza virus retain traces of interspecies transmission and adaptation. Previous phylogenetic analyses highlighted mutations L298I, R386K and I517V in PB1 to have putatively ameliorated the A(H1N1)pdm09 adaptation to the human host. This study aimed to evaluate the reversal of these mutations and infer the role of these residues in the virus overall fitness and adaptation. We generate PB1-mutated viruses introducing I298L, K386R and V517I mutations in PB1 and evaluate their phenotypic impact on viral growth and on antigen yield. We observed a decrease in viral growth accompanied by a reduction in hemagglutination titer and neuraminidase activity, in comparison with wt. Our data indicate that the adaptive evolution occurred in the PB1 leads to an improved overall viral fitness; and such biologic advantaged has the potential to be applied to the optimization of influenza vaccine seed prototypes.

Influenza A(H1N1)pdm09 Virus Alters Expression of Endothelial Factors in Pulmonary Vascular Endothelium in Rats.

Influenza virus infection may cause endothelial activation and dysfunction. However, it is still not known to what extent the influenza virus can dysregulate the expression of various endothelial proteins. The aim of the study is to identify the level of expression of endothelial nitric oxide synthase (eNOS), plasminogen activator inhibitor-1 (PAI-1), and tissue plasminogen activator (tPA) in the pulmonary vascular endothelium, as well as the concentration of PAI-1 and tPA in the blood plasma in Wistar rats. Animals were intranasally infected with rat-adapted influenza A(H1N1)pdm09 virus. The expression of eNOS, PAI-1 and tPA in the pulmonary vascular endothelium was determined by immunohistochemistry; the concentration of PAI-1 and tPA was analyzed by ELISA at 24 and 96 h post infection (hpi). Thus, the expression of eNOS in the pulmonary vascular endothelium decreased by 1.9-fold at 24 hpi and increased by 2-fold at 96 hpi. The expression of PAI-1 in the pulmonary vascular endothelium increased by 5.23-fold and 6.54-fold at 24 and 96 hpi, respectively. The concentration of PAI-1 in the blood plasma of the rats decreased by 3.84-fold at 96 hpi, but not at 24 hpi. The expression of tPA in the pulmonary vascular endothelium was increased 2.2-fold at 96 hpi. The obtained data indicate the development of endothelial dysfunction that is characterized by the dysregulation of endothelial protein expression in non-lethal and clinically non-severe experimental influenza virus infection.

Evaluation of panel of neutralising murine monoclonal antibodies and a humanised bispecific antibody against influenza A(H1N1)pdm09 virus infection in a mouse model

The influenza A (H1N1) pdm09 virus attracted public attention because of its high prevalence. The annual global morbidity and mortality rates of influenza remain high despite the application of influenza vaccines and antiviral drugs, which indicates the urgent need to identify a more effective strategy for controlling and treating A(H1N1) pdm09 influenza infection. To produce a highly effective therapeutic with broad specificity for A(H1N1) pdm09 influenza viruses, we generated 15 murine monoclonal antibodies (mAbs) via hybridoma technology: 11 mAbs demonstrated 20–100% therapeutic protection in a mouse model of A(H1N1) pdm09 infection at a single dose of 10 mg/kg. A humanised bispecific antibody (Bis-Hu11-1) generated based on the mAbs 3D2 and 3D11, combining the specificities of the two mAbs, was also effective in preventing and treating A(H1N1) pdm09 infection in a mouse model. Bis-Hu11-1 demonstrated hemagglutination inhibition (HI) activity against the escape mutants generated by its parental mAbs that resulted in the obvious reduction in the HI activity of the parental mAbs. In summary, we generated a panel of neutralising mAbs against A(H1N1) pdm09 influenza virus. This study presents a promising method for developing neutralising antibodies that potentially target a series of antigenically diverse influenza viruses.

Assessing the fitness of a dual-antiviral drug resistant human influenza virus in the ferret model

Influenza antivirals are important tools in our fight against annual influenza epidemics and future influenza pandemics. Combinations of antivirals may reduce the likelihood of drug resistance and improve clinical outcomes. Previously, two hospitalised immunocompromised influenza patients, who received a combination of a neuraminidase inhibitor and baloxavir marboxil, shed influenza viruses resistant to both drugs. Here-in, the replicative fitness of one of these A(H1N1)pdm09 virus isolates with dual resistance mutations (NA-H275Y and PA-I38T) was similar to wild type virus (WT) in vitro, but reduced in the upper respiratory tracts of challenged ferrets. The dual-mutant virus transmitted well between ferrets in an airborne transmission model, but was outcompeted by the WT when the two viruses were co-administered. These results indicate the dual-mutant virus had a moderate loss of viral fitness compared to the WT virus, suggesting that while person-to-person transmission of the dual-resistant virus may be possible, widespread community transmission is unlikely.

Zooming in on the molecular characteristics of swine influenza virus circulating in Colombia before and after the H1N1pdm09 virus.

Influenza is one of the most critical viral agents involved in the respiratory disease complex affecting swine production systems worldwide. Despite the absence of vaccination against swine influenza virus in Colombia, the serologic reactivity to classic H1N1 and H3N2 subtypes reported since 1971 indicates the virus has been circulating in the country's swine population for several decades. However, successful isolation and sequencing of field virus from pigs was nonexistent until 2008, when H1N1 classical influenza virus was identified. One year later, due to the emergence of the influenza A (H1N1) pdm09 virus, responsible for the first global flu pandemic of the 21st century, it was introduced in the country. Therefore, to understand the impact of the introduction of the H1N1pdm09 virus in Colombia on the complexity and dynamics of influenza viruses previously present in the swine population, we carried out a study aiming to characterize circulating viruses genetically and establish possible reassortment events that might have happened between endemic influenza viruses before and after the introduction of the pandemic virus. A phylogenetic analysis of ten swine influenza virus isolates from porcine samples obtained between 2008 and 2015 was conducted. As a result, a displacement of the classical swine influenza virus with the pdmH1N1 virus in the swine population was confirmed. Once established, the pandemic subtype exhibited phylogenetic segregation based on a geographic pattern in all the evaluated segments. The evidence presents reassortment events with classic viruses in one of the first H1N1pdm09 isolates. Thus, this study demonstrates complex competition dynamics and variations in Colombian swine viruses through Drift and Shift.

Characteristics of the Epidemic Situation Associated with Acute Respiratory Viral Infections in the Russian Federation during the Pandemic Spread of COVID-19

Annualy, SARS occupy a leading position in terms of morbidity and the magnitude of the economic damage caused both in the world and in the Russian Federation. Currently, the most widespread pandemics are caused by the influenza A (H1N1) pdm09 virus and the new SARS-CoV-2 coronavirus, which occupy a common ecological niche and require studying the manifestations of the epidemic process of ARVI for further development of measures to improve epidemiological surveillance of this group of infections. Aim of the study was to investigate the current manifestations of the epidemic process of ARVI and influenza, including in the context of a new coronavirus infection (COVID–19) pandemic, on the territory of Russia and in Moscow. Materials and methods. The assessment of the long-term dynamics of the incidence of ARVI and influenza (from 1999 to 2021), as well as its age structure in the territory of the Russian Federation and in Moscow, was carried out. The main sources of information were: WHO: «The situation with COVID-19 in the European region», the domestic information portal Stopkoronavirus.rf, as well as data from Federal State Statistical Observation forms No. 2 and No. 6. Results. During the period 2013–2019, a strong positive correlation was revealed between the incidence rates of ARVI in the Russian Federation and Moscow (p = 0.8, with p &lt; 0.05), which became negative with the spread of SARS-CoV-2: in the country, the incidence rate of ARVI increased by 11.5% in 2020 and 15.6% in 2021., in Moscow there was a decrease of 45.1% than the average in Russia, which could be due to the quality of differential diagnosis of ARVI and COVID-19. In 2021 the incidence rate of influenza decreased by more than 2 times in all Federal Districts of the country, with the exception of the capital region, where it became the maximum - 65.9 per 100 thousand population in 2021 (against 14.1 in 2019). In the age structure of influenza incidence, as well as ARVI, for the period from 2019 to 2021. the child population prevailed with the highest rates in the age groups of 1–2 years and 3–6 years. As the circulation of SARS-Cov-2 decreased to 15–19%, the activity of influenza viruses and other pathogens of the ARVI group increased (from 0.7–3.0% during the developed pandemic to 5.6–6.6% at the stage of its decline), which indicates a pronounced interference of pathogens detected at the global level in the system of Global Hospital Surveillance for flu. Conclusion. The forecast for the upcoming epidemic season 2022–2023 largely depends on the spread of the new coronavirus SARS-CoV-2, as well as its variability and the emergence of new variants. Nevertheless, there may be a significant increase in the incidence caused by the influenza A(H1N1)pdm09 virus, whose high activity was recorded in the current epidemic season in a number of countries in the Southern hemisphere.