The Global Circulation of Seasonal Influenza A (H3N2) Viruses

Abstract

Antigenic and genetic analysis of the hemagglutinin of approximately 13,000 human influenza A (H3N2) viruses from six continents during 2002-2007 revealed that there was continuous circulation in east and Southeast Asia (E-SE Asia) via a region-wide network of temporally overlapping epidemics and that epidemics in the temperate regions were seeded from this network each year. Seed strains generally first reached Oceania, North America, and Europe, and later South America. This evidence suggests that once A (H3N2) viruses leave E-SE Asia, they are unlikely to contribute to long-term viral evolution. If the trends observed during this period are an accurate representation of overall patterns of spread, then the antigenic characteristics of A (H3N2) viruses outside E-SE Asia may be forecast each year based on surveillance within E-SE Asia, with consequent improvements to vaccine strain selection.

Adamantane- and Oseltamivir-Resistant Seasonal A (H1N1) and Pandemic A (H1N1) 2009 Influenza Viruses in Guangdong, China, during 2008 and 2009

“…tible ORV. Further studies are required to investigate possible mechanisms underlying the fitness improvement of these recombinant viruses, but our findings stress the need for systematic surveillance of resistance, particularly in regions known to be at risk for reassortment due to local epidemiological factors (20). The cocirculation of these double-resistant seasonal influenza viruses and the pandemic A (H1N1) 2009 strains in September in Guangdong exemplifies this risk.…”

“…Thus, the emergence of ORVs in 2009 in Guangdong most likely reflects seeding of strains through importation, as Guangdong is highly connected to the rest of the world though travel and trade (20).…”

“…This is particularly relevant in regions known to be hot spots for emergence of influenza virus variants (20). To characterize local patterns of emerging antiviral resistance, we studied the prevalence of adamantane-and oseltamivir-resistant seasonal A (H1N1) and pandemic A (H1N1) 2009 viruses in Guangdong Province, China.…”

Origin, distribution, and potential risk factors associated with influenza A virus in swine in two production systems in Guatemala

“…The amount of data available for human influenza for Central America is extremely limited, and Central America is not considered a major contributor to the epidemiology of human influenza in a continental scale 43. A low connection of Central American countries by air travel 44 summed to differences in influenza seasonality in the Neotropics 31 may facilitate the circulation of virus populations genetically different in this region. The mutations in the HA1 protein of 040078‐H3N2 in comparison with the vaccine strains suggest differences in antigenicity with other viruses of human origin.…”

Conjugating drug candidates to polymeric chains does not necessarily enhance anti‐influenza activity

“…To explore this possibility, we ran in silico docking experiments to determine the preferred binding sites for the monomeric inhibitor 10 and the linker-attached inhibitor 16 for the Puerto Rico strain and a Wuhan surrogate strain, X-31 (both H3N2). Note that the X-31 strain has a 87% sequence identity for the HA1 strand of the hemagglutinin molecule compared to the Wuhan strain (the HA2 Wuhan sequence is unavailable) 27, 28 (for comparison, the Puerto Rico's HA1 strand has just a 33% sequence identity 29 ). As seen in Figure 4A, for the X-31 strain both inhibitors bind in the same region of the hemagglutinin protein; this region coincides with the crystallographically determined binding site for tert-butyl hydroquinone (another fusion inhibitor described by Bodian et al 12,19 ).…”