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. One month later, after a sudden increase in deaths, H7N3 highly pathogenic avian influenza (HPAI) virus was isolated. Sequence analysis of all eight genes of the LPAI virus and the HPAI viruses showed minor differences between the viruses except at the hemagglutinin (HA) cleavage site. The LPAI virus had a cleavage site similar to other low pathogenic H7 viruses, but the HPAI isolates had a 30 nucleotide insert. The insertion likely occurred by recombination between the HA and nucleoprotein genes of the LPAI virus, resulting in a virulence shift. Sequence comparison of all eight gene segments showed the Chilean viruses were also distinct from all other avian influenza viruses and represent a distinct South American clade

Characterization of Newcastle disease viruses isolated from chickens and pigeons in the South Marmara region of Turkey

Between December 1992 and April 1993, Newcastle disease (ND) outbreaks occurred in a broiler flock, a layer flock, in village chickens of two prefectures and in five pigeon lofts in the South Marmara Region of Turkey. Four viruses from chickens and five from pigeons were isolated from these outbreaks, and identified as Newcastle disease viruses (NDV). All were characterized as velogenic strains based on their mean death time in eggs, ability to form plaques in tissue culture and, for some isolates, intracerebral pathogenicity index and intravenous pathogenicity index tests. Monoclonal antibody typing showed that eight of the nine isolates were indistinguishable from each other

A sensitive retroviral pseudotype assay for influenza H5N1-neutralizing antibodies

Background The World Health Organisation (WHO) recommended the development of simple, safe, sensitive and specific neutralization assays for avian influenza antibodies. We have used retroviral pseudotypes bearing influenza H5 hemagglutinin (HA) as safe, surrogate viruses for influenza neutralization assays which can be carried out at Biosafety Level 2. Results Using our assay, sera from patients who had recovered from infection with influenza H5N1, and sera from animals experimentally immunized or infected with H5 tested positive for the presence of neutralizing antibodies to H5N1. Pseudotype neutralizing antibody titers were compared with titers obtained by hemagglutinin inhibition (HI) assays and microneutralization (MN) assays using live virus, and showed a high degree of correlation, sensitivity and specificity. Conclusions The pseudotype neutralization assay is as sensitive as horse erythrocyte HI and MN for the detection of antibodies to H5N1. It is safer, and can be applied in a high-throughput format for human and animal surveillance and for the evaluation of vaccines

Supplementary Tables from Antibody responses to avian influenza viruses in wild birds broaden with age

Results of statistical analysi

Supplementary Figure 1 from Antibody responses to avian influenza viruses in wild birds broaden with age

Cumulative proportion of birds sampled during each sampling year and in the population

Supplementary Figure 2 from Antibody responses to avian influenza viruses in wild birds broaden with age

Change in HI titre for each antigen between 2007 and 2008 for each of the eleven birds that were sampled in both years