Phylogenetic Analysis of H7 Avian Influenza Viruses Isolated from the Live Bird Markets of the Northeast United States

Abstract

The presence of low-pathogenic H7 avian influenza virus (AIV), which is associated with live-bird markets (LBM) in the Northeast United States, was first detected in 1994 and, despite efforts to eradicate the virus, surveillance of these markets has resulted in numerous isolations of H7 AIVs from several states from 1994 through 1998. The hemagglutinin, nonstructural, and matrix genes from representative H7 isolates from the LBM and elsewhere were sequenced, and the sequences were compared phylogenetically. The hemagglutinin gene of most LBM isolates examined appeared to have been the result of a single introduction of the hemagglutinin gene. Evidence for evolutionary changes were observed with three definable steps. The first isolate from 1994 had the amino acid threonine at the −2 position of the hemagglutinin cleavage site, which is the most commonly observed amino acid at this site for North American H7 AIVs. In January 1995 a new genotype with a proline at the −2 position was detected, and this genotype eventually became the predominant virus isolate. A third viral genotype, detected in November 1996, had an eight-amino-acid deletion within the putative receptor binding site. This viral genotype appeared to be the predominant isolate, although isolates with proline at the −2 position without the deletion were still observed in viruses from the last sampling date. Evidence for reassortment of multiple viral genes was evident. The combination of possible adaptive evolution of the virus and reassortment with different influenza virus genes makes it difficult to determine the risk of pathogenesis of this group of H7 AIVs.

Live poultry market workers are susceptible to both avian and swine influenza viruses, Guangdong Province, China

“…Pigs have been known to serve as a "mixing vessel" of influenza viruses from multiple species. Reassortment of viruses from different species tends to occur in pigs, which go on to infect humans (Smith et al, 2009a); LPMs provide an optimal opportunity for reassortment and are suspected to have contributed to the emergence of avian influenza virus H7N9 (Pepin et al, 2013;Suarez et al, 1999;Wang et al, 2006).…”

Emerging Respiratory Viruses: Challenges and Vaccine Strategies

“…Antigenic shift results in the generation of viruses containing HAs to which the majority of the human population is naïve and can cause an influenza pandemic if the virus spreads efficiently from personto-person. Although recombination events are rare, there are reports of recombination between the HA and other viral gene segments and possibly with cellular DNA among H7 viruses (186).…”

“…(c) H7N7 avian influenza virus. Outbreaks of highly pathogenic avian influenza virus H7N7 infection were reported in birds beginning in 1975 (1,139,186). Isolated cases of human infections with this subtype of influenza virus transmitted from birds and harbor seals have been reported (4,106).…”

Quail carry sialic acid receptors compatible with binding of avian and human influenza viruses

“…The first reported case of influenza A respiratory disease in quail occurred in Italy during 1966 to 1968 (Nardelli et al, 1970). Influenza viruses have since been isolated from quail in sporadic surveillance studies in North America, Europe and Asia (Guan et al, 1999;Saito et al, 1993;Suarez et al, 1999), and it appears that certain subtypes (H6, H9) of influenza viruses have established stable lineages in this species in Asia (Chin et al, 2002;Guan et al, 1999Guan et al, , 2000Guan et al, , 2002Guan et al, , 2004. Interestingly, quail infected with the highly pathogenic virus Turkey/Ontario/7732/66 (H5N9) showed no signs of disease but could transmit the virus to chickens and cause death (Tashiro et al, 1987).…”