Isolation and Characterization of H3N2 Influenza A Virus from Turkeys

Abstract

Five 34-wk-old turkey breeder layer flocks in separate houses of 2550 birds each in a single farm in Ohio experienced a drop in egg production from late January to early February 2004. Tracheal swabs (n = 60), cloacal swabs (n = 50), and convalescent sera (n = 110) from the flocks were submitted to the laboratory for diagnostics. Virus isolation was attempted in specific-pathogen free embryonating chicken eggs and Vero and MDCK cells. Virus characterization was performed using agar gel immunodiffusion, the hemagglutination test, the hemagglutination inhibition test, the virus neutralization test, reverse transcription-polymerase chain reaction, sequencing, and phylogenetic analysis. A presumptive influenza virus was successfully propagated and isolated on the first passage in MDCK cells, but initially not in Vero cells or specific-pathogen free chicken embryos. After two passages in MDCK cells, it was possible to propagate the isolate in specific-pathogen free chicken embryos. Preliminary sequence analysis of the isolated virus confirmed that it was influenza A virus with almost 100% (235/236) identity with the matrix gene of a swine influenza A virus, A/Swine/Illinois/100084/01 (H1N2). However, it was not possible to subtype the virus using conventional serotyping methods. The results of genetic characterization of the isolated virus showed that it was the H3N2 subtype and was designated as A/Turkey/OH/313053/04 (H3N2). Phylogenetic analysis of the eight gene segments of the virus showed that A/Turkey/OH/313053/04 (H3N2) isolate was most closely related to the triple-reassortant H3N2 swine viruses [A/Swine/WI/14094/99 (H3N2)] that have been circulating among pigs in the United States since 1998, which contains gene segments from avian, swine, and human viruses. The A/Turkey/OH/313053/04 (H3N2) isolated from turkeys in this study was classified as a low pathogenic avian influenza A virus because it only caused a drop in egg production with minor other clinical signs and no mortality.

Modifications in the Polymerase Genes of a Swine-Like Triple-Reassortant Influenza Virus To Generate Live Attenuated Vaccines against 2009 Pandemic H1N1 Viruses

“…With the aim of developing temperature-sensitive LAIVs against the H1N1pdm virus, we have used reverse genetics to introduce attenuation markers into the polymerase genes of a swine-like TR H3N2 influenza virus, A/turkey/Ohio/313053/04 (H3N2) (ty/04) (66). We chose this isolate because it grows well in both eggs and cell culture-based substrates, displays a broad host range, and has internal genes similar to those of the H1N1pdm virus.…”

“…Thus, the introduction of genetic signatures for att into the backbone of a swine-like TR influenza virus resulted in highly attenuated and efficacious live influenza vaccines with promising applications in both human and veterinary medicine. A/turkey/Ohio/313053/04 (H3N2) (ty/04) has been described previously and was kindly provided by Yehia Saif, Ohio State University, Wooster (66). A/California/04/09 (H1N1) (Ca/04) was kindly provided by the CDC, Atlanta, GA.…”

PB1-F2 Protein Does Not Impact the Virulence of Triple-Reassortant H3N2 Swine Influenza Virus in Pigs but Alters Pathogenicity and Transmission in Turkeys

“…their respiratory tract (18). Turkeys are highly susceptible to IAV from aquatic birds (21,51), and with the introduction of SIV, there is an increasing chance for the emergence of novel reassortants with genes adapted for replication in pigs or even humans (20,21). Hence, it is important to study the role of PB1-F2 in the pathogenesis and transmission of TR H3N2 SIV in turkeys.…”

“…Interestingly, SIV 1145-N66S virus-infected turkey poults showed poor infectivity and were not transmitted efficiently among the in-contacts. Most of the SIV outbreaks in turkeys in the United States occurred in older flocks and generally are associated with a drop in egg production (19,21). Strong evidence of turkey-to-turkey transmission also was recorded (20).…”

“…Turkeys are susceptible to a wide range of IAVs; hence, they serve as an important intermediate host for IAVs (19). In 2003, some of the TR H3N2 SIVs crossed the species barrier and caused outbreaks in domestic turkey farms situated in Minnesota and North Carolina (20,21) and is now a prevalent virus in turkeys.…”