Characterization of Variations in PB2, NS1, M, Neuraminidase and Hemagglutinin of Influenza A (H3N2) Viruses in Iran

Long-term co-circulation of multiple influenza A viruses in pigs, Guangxi, China

Influenza A viruses (IAVs) pose a persistent potential threat to human health because of the spillover from avian and swine infections. Extensive surveillance was performed in 12 cities of Guangxi, China, during 2018 and 2023. A total of 2540 samples (including 2353 nasal swabs and 187 lung tissues) were collected from 18 pig farms with outbreaks of respiratory disease. From these, 192 IAV-positive samples and 19 genomic sequences were obtained. We found that the H1 and H3 swine influenza A viruses (swIAVs) of multiple lineages and genotypes have continued to co-circulate during that time in this region. Genomic analysis revealed the Eurasian avian-like H1N1 swIAVs (G4) still remained predominant in pig populations. Strikingly, the novel multiple H3N2 genotypes were found to have been generated through the repeated introduction of the early H3N2 North American triple reassortant viruses (TR H3N2 lineage) that emerged in USA and Canada in 1998 and 2005, respectively. Notably, when the matrix gene segment derived from the H9N2 avian influenza virus was introduced into endemic swIAVs, this produced a novel quadruple reassortant H1N2 swIAV that could pose a potential risk for zoonotic infection.

Assessment of influenza A (H1N1, H3N2) oseltamivir resistance during 2017-2019 in Iran

Background and Objectives

Neuraminidase inhibitors (NAIs) as an imperative antiviral for influenza prophylaxis and treatment are being consumed worldwide. Increasing use of these antivirals might be associated with drug resistance. Regarding the significance of these variations, this study aimed to investigate the mutations occurring in the NA gene of influenza A viruses leading to oseltamivir resistance during 2017-2019 in Iran.

Materials and Methods

In this cross-sectional study, 40 influenza A (H1N1, H3N2) strains, isolated in National Influenza Center (NIC) from patients with Severe Acute Respiratory Infection (SARI) during 2017-2019 were subjected to RT-PCR and sequencing of NA complete gene. The frequency of oseltamivir resistance and variation of NA amino acids in these strains were investigated.

Results

No significant mutation conferring oseltamivir resistance was detected. However, NA antigenic sites in these strains depicted minor changes compared to the vaccine strains. Among H3N2 isolates, mutations at 329, 344, 346 and 385 and among H1N1 isolates mutations at 143 and 188 residues occurred in NA antigenic regions.

Conclusion

Evaluation of NA gene sequences, showed no resistant viruses to oseltamivir. Given that the viruses in the present study were the last viruses circulating in Iran before COVID-19 pandemic, the results will be beneficial to have a worthy comparison with the strains circulating after the pandemic. Constant monitoring for the emergence of drug-resistant variants and antigenic changes are crucial for all countries.

Trends in surveillance data of influenza virus in Tehran before decreasing dispatch of Iranian Hajj pilgrims to Mecca

Background: Respiratory infections, especially viral infections, are the most prevalent infection affecting Hajj pilgrims. Commonly major human influenza viruses (A/H1N1, A/H3N2, and B) are responsible for these morbidities. The present study was conducted to develop a statistical report on human influenza in Hajj pilgrims.

Methods: Nasal and throat samples were collected from 232 returning Iranian pilgrims in hospitals of IUMS. All samples were kept in the refrigerator at 4 °C and stored at −70 °C until RNA extraction. RNA extraction was performed by QIAamp viral RNAmini kits (QIAGEN, Hilden, Germany) and influenza viruses were detected by TaqMan RT-PCR.

Results: Participants included 115 (49.5%) male and 117 (50.5%) female patients, with the age range of 10 to 93 years (mean: 53 years). The pandemic and seasonal influenza A (H1N1) virus were detected in 2 (0.8%) and 20 (8.6%) pilgrims, respectively, and also influenza B was identified in 1 person (0.4%).

Conclusions: Since the probability of an influenza pandemic has been anticipated for the coming years, it seems necessary to plan a continuous monitoring of large gatherings like Hajj and conduct statistical studies in the region. Moreover, material surveillance in humans needs to be boosted. Therefore, results of influenza research can be important for developing WHO reports.