The 1957 and 1968 influenza pandemics, each of which killed ≈1 million persons, arose through reassortment events. Influenza virus in humans and domestic animals could reassort and cause another pandemic. To identify geographic areas where agricultural production systems are conducive to reassortment, we fitted multivariate regression models to surveillance data on influenza A virus subtype H5N...

Multiplex PCR assays that can detect and identify three haemagglutinins and two neuraminidases of three main subtypes: H1N1, H1N2, and H3N2 of swine influenza virus (SIV), circulating in a pig population, were developed. Three oligonucleotide primer sets were evaluated based on the published sequences, with unique sizes characteristic for each subtype. The sequences of each primers were demonst...

In 1999, the World Health Organization switched from annual to semi-annual recommendations for influenza vaccine composition. We compared the antigenic match between recommendations and circulating viruses before and after 1999, in the Northern and Southern Hemispheres. Vaccine match proportion for A/H3N2 viruses increased from 31% to 59% in the Southern Hemisphere (P<0.05), and is now comparab...

In this study, three subtypes of influenza A viruses (pH1N1, H5N1 and H3N2) which naturally infected human were analyzed by bioinformatic approaches to find candidate human cellular miRNAs targeting viral genomes. There were 76 miRNAs targeting influenza A viruses. Among these candidates, 70 miRNAs were subtypes specifically targeting each subtype of influenza A virus including 21 miRNAs target...

Despite a mass of research on the epidemiology of seasonal influenza, overall patterns of infection have not been fully described on broad geographic scales and for specific types and subtypes of the influenza virus. Here we provide a descriptive analysis of laboratory-confirmed influenza surveillance data by type and subtype (A/H3N2, A/H1N1, and B) for 19 temperate countries in the Northern an...

The distribution and prevalence of H3 subtype influenza viruses in avian and mammalian hosts constitutes a potential threat to both human and avian health. We report a complete genome sequence of a novel reassortant H3N2 avian influenza virus. Phylogenetic analysis showed that HA and NA showed the highest sequence homologies with those of A/white-backed munia/Hong Kong/4519/2009 (H3N2). However...

The 2012/13 influenza season in Canada has been characterised to date by early and moderately severe activity, dominated (90%) by the A(H3N2) subtype. Vaccine effectiveness (VE) was assessed in January 2013 by Canada's sentinel surveillance network using a test-negative case-control design. Interim adjusted-VE against medically attended laboratory-confirmed influenza A(H3N2) infection was 45% (...

BACKGROUND In 2011, a new variant of influenza A(H3N2) emerged that contained a recombination of genes from swine H3N2 viruses and the matrix (M) gene of influenza A(H1N1)pdm09 virus. New combinations and variants of pre-existing influenza viruses are worrisome if there is low or nonexistent immunity in a population, which increases chances for an outbreak or pandemic. METHODS Sera collected ...

Since December 1998 when swine influenza virus (SIV) with H3N2 was first identified in Iowa swine, prospective and retrospective studies were conducted to monitor and evaluate H3N2 SIV infections in swine population in Iowa until February 2000. A serological survey revealed that H3 SIV had been widely spread in Iowa swine within first 6 months after initial identification and that both H1 and H...

We have generated recombinant influenza A viruses belonging to the H1N1 and H3N2 virus subtypes containing an insertion of the 137 C-terminal amino acid residues of the human immunodeficiency virus type 1 (HIV-1) Nef protein into the influenza A virus nonstructural-protein (NS1) reading frame. These viral vectors were found to be genetically stable and capable of growing efficiently in embryona...