Molecular Characterization of Pandemic H1N1 Influenza Viruses Isolated from Turkeys and Pathogenicity of a Human pH1N1 Isolate in Turkeys

Abstract

Suspected human-to-animal transmission of the 2009 pandemic H1N1 (pH1N1) virus has been reported in several animal species, including pigs, dogs, cats, ferrets, and turkeys. In this study we describe the genetic characterization of pH1N1 viruses isolated from breeder turkeys that was associated with a progressive drop in egg production. Sequence analysis of all eight gene segments from three viruses isolated from this outbreak demonstrated homology with other human and swine pH1N1 isolates. The susceptibility of turkeys to a human pH1N1 isolate was further evaluated experimentally. The 50% turkey infectious dose (TID50) for the human isolate A/Mexico/LnDRE/4487/2009 was determined by inoculating groups of 8-10-week-old turkeys with serial 10-fold dilutions of virus by oronasal and cloacal routes. We estimated the TID50 to be between 1 x 10(5) and 1 x 10(6) TCID50. The pathogenesis of pH1N1 in oronasally or cloacally inoculated juvenile turkeys was also examined. None of the turkeys exhibited clinical signs, and no significant difference in virus shedding or seroconversion was observed between the two inoculation groups. More than 50% of the turkeys in both oronasal and cloacal groups shed virus beginning at 2 days postinoculation (dpi). All birds that actively shed virus seroconverted by 14 dpi. Virus antigen was demonstrated by immunohistochemistry in the cecal tonsils and bursa of Fabricius in two of the birds that were infected by the cloacal route. Virus transmission to naive contact turkeys was at best doubtful. This report provides additional evidence that pH1N1 can cross the species barrier and cause disease outbreaks in domestic turkeys. However, it appears that the reproductive status of the host as well as environmental factors such as concurrent infections, stress, the presence or absence of litter, and stocking density may also contribute to efficient infection and transmission of this agent.

Combination of PB2 271A and SR Polymorphism at Positions 590/591 Is Critical for Viral Replication and Virulence of Swine Influenza Virus in Cultured Cells and In Vivo

“…Avian-origin PB2 with 627E was introduced into North American SIVs more than 10 years ago, and this avian-like signature (i.e., 627E) remains stable rather than changing to the mammalian-like signature (i.e., 627K) (8). The pH1N1 viruses have circulated in humans for more than 2 years and have been transmitted to other animal species (1,3,11,15), yet almost all of the isolates still contain the avian-like signature 627E instead of the mammalian-like signature 627K in their PB2 proteins. The PB2 271A of pH1N1 contributes to enhance viral polymerase activity and growth in mammalian cells (2).…”

Increased Pathogenicity of a Reassortant 2009 Pandemic H1N1 Influenza Virus Containing an H5N1 Hemagglutinin

“…In the spring of 2009, a novel influenza virus of swine origin (pH1N1) emerged and rapidly spread across the globe, and it was recognized by the World Health Organization as the first influenza pandemic of the 21st century (3,11). We are currently in the recovery phase of this pandemic, but pH1N1 virus is now the dominant H1N1 virus circulating in humans.…”

Human to animal transmission of influenza A(H1N1)pdm09 in a turkey breeder flock in Norway

“…Suspected cases of human to animal transmission of influenza A(H1N1)pdm09 (H1N1pdm09) virus have been reported in several mammalian species, including pigs, dogs, cats, and ferrets [3]. Although poultry has been regarded as less susceptible to the H1N1pdm09 virus [4], several international case reports have described H1N1pdm09 infection of suspected human origin in turkeys in the wake of the 2009 pandemic [5–8]. The transmission has occurred solely in turkey breeders, most likely during artificial insemination [9].…”