Serological Evidence for Influenza A Virus Exposure in Wild Birds in Trinidad & Tobago.

Migratory waterfowl and shorebirds are known to be important reservoirs for influenza A viruses (IAV) and they have been repeatedly implicated as causing avian influenza virus (AIV) outbreaks in domestic poultry flocks worldwide. In recent years, wild birds have been implicated in spreading zoonotic H5 influenza viruses to many countries, which has generated high levels of public health concern. Trinidad and Tobago (T&T) is positioned along the wintering route of migratory birds from the Americas; every year, many species of wild birds stopover on the islands of T&T, potentially carrying AIVs and exposing local populations of wild and domestic birds, including commercial poultry, to infection.

Virus pathotype and deep sequencing of the HA gene of a low pathogenicity H7N1 avian influenza virus causing mortality in Turkeys.

Low pathogenicity avian influenza (LPAI) viruses of the H7 subtype generally cause mild disease in poultry. However the evolution of a LPAI virus into highly pathogenic avian influenza (HPAI) virus results in the generation of a virus that can cause severe disease and death. The classification of these two pathotypes is based, in part, on disease signs and death in chickens, as assessed in an intravenous pathogenicity test, but the effect of LPAI viruses in turkeys is less well understood.

First reported detection of influenza A (H1N1)pdm09 in turkeys in the United Kingdom.

We report the first occurrence of pandemic (H1N1) 2009 virus [A(H1N1)pdm09] infection on two epidemiologically linked turkey breeder premises in the United Kingdom during December 2010 and January 2011. Clinically, the birds showed only mild signs of disease, with the major presenting sign being an acute and marked reduction in egg production, leading to the prompt reporting of suspected avian notifiable disease for official investigation. Presence of A(H1N1)pdm09 infection in the United Kingdom turkey breeder flocks was confirmed by detailed laboratory investigations including virus isolation in embryonated specific pathogen-free fowls' eggs, two validated real-time reverse transcription-PCR tests, and nucleotide sequencing of the hemagglutinin and neuraminidase genes.

Quantifying transmission of highly pathogenic and low pathogenicity H7N1 avian influenza in turkeys.

Outbreaks of avian influenza in poultry can be devastating, yet many of the basic epidemiological parameters have not been accurately characterised. In 1999-2000 in Northern Italy, outbreaks of H7N1 low pathogenicity avian influenza virus (LPAI) were followed by the emergence of H7N1 highly pathogenic avian influenza virus (HPAI). This study investigates the transmission dynamics in turkeys of representative HPAI and LPAI H7N1 virus strains from this outbreak in an experimental setting, allowing direct comparison of the two strains.

Selection of variant viruses during replication and transmission of H7N1 viruses in chickens and turkeys.

The influence of different glycosylation patterns of the haemagglutinin glycoprotein of H7N1 avian influenza viruses on virus replication in vivo was examined. Experimental infection of chickens and turkeys was carried out with H7N1 avian influenza viruses with alternative sites of glycosylation in the haemagglutinin and infected birds were sampled daily by swabbing the buccal and cloacal cavities. cDNAs of the HA1 coding region of the HA gene were prepared from the swabs and cloned into plasmids.

Reassortant Pandemic (H1N1) 2009 virus in pigs, United Kingdom.

Surveillance for influenza virus in pigs in the United Kingdom during spring 2010 detected a novel reassortant influenza virus. This virus had genes encoding internal proteins from pandemic (H1N1) 2009 virus and hemagglutinin and neuraminidase genes from swine influenza virus (H1N2). Our results demonstrate processes contributing to influenza virus heterogeneity.

Within-host variation of avian influenza viruses.

The emergence and spread of H5N1 avian influenza viruses from Asia through to Europe and Africa pose a significant animal disease problem and have raised concerns that the virus may pose a pandemic threat to humans. The epizootological factors that have influenced the wide distribution of the virus are complex, and the variety of viruses currently circulating reflects these factors. Sequence analysis of the virus genes sheds light on the H5N1 virus evolution during its emergence and spread, but the degree of virus variation at the level of an individual infected bird has been described in only a few studies.

Significant rising antibody titres to influenza A are associated with an acute reduction in milk yield in cattle.

Sporadic cases of an acute fall in milk production, "milk drop", were investigated in a Holstein Friesian dairy herd in Devon. The investigation was a case control study with two controls per case. Paired blood samples demonstrated that rising antibody titres to human influenza A/England/333/80 (H1N1) and human influenza A/Eng/427/88 (H3N2) were associated with an acute fall in milk production.

Recombination resulting in virulence shift in avian influenza outbreak, Chile.

Influenza A viruses occur worldwide in wild birds and are occasionally associated with outbreaks in commercial chickens and turkeys. However, avian influenza viruses have not been isolated from wild birds or poultry in South America. A recent outbreak in chickens of H7N3 low pathogenic avian influenza (LPAI) occurred in Chile.