Acquisition of Human-Type Receptor Binding Specificity by New H5N1 Influenza Virus Sublineages during Their Emergence in Birds in Egypt

Highly pathogenic avian influenza A virus subtype H5N1 is currently widespread in Asia, Europe, and Africa, with 60% mortality in humans. In particular, since 2009 Egypt has unexpectedly had the highest number of human cases of H5N1 virus infection, with more than 50% of the cases worldwide, but the basis for this high incidence has not been elucidated. A change in receptor binding affinity of the viral hemagglutinin (HA) from α2,3- to α2,6-linked sialic acid (SA) is thought to be necessary for H5N1 virus to become pandemic. In this study, we conducted a phylogenetic analysis of H5N1 viruses isolated between 2006 and 2009 in Egypt. The phylogenetic results showed that recent human isolates clustered disproportionally into several new H5 sublineages suggesting that their HAs have changed their receptor specificity. Using reverse genetics, we found that these H5 sublineages have acquired an enhanced binding affinity for α2,6 SA in combination with residual affinity for α2,3 SA, and identified the amino acid mutations that produced this new receptor specificity. Recombinant H5N1 viruses with a single mutation at HA residue 192 or a double mutation at HA residues 129 and 151 had increased attachment to and infectivity in the human lower respiratory tract but not in the larynx. These findings correlated with enhanced virulence of the mutant viruses in mice. Interestingly, these H5 viruses, with increased affinity to α2,6 SA, emerged during viral diversification in bird populations and subsequently spread to humans. Our findings suggested that emergence of new H5 sublineages with α2,6 SA specificity caused a subsequent increase in human H5N1 influenza virus infections in Egypt, and provided data for understanding the virus's pandemic potential

Detection of infectious bronchitis virus 793B, avian metapneumovirus, Mycoplasma gallisepticum and Mycoplasma synoviae in poultry in Ethiopia

A survey was conducted into respiratory infectious diseases of poultry on a chicken breeder farm run by the Ethiopian Institute of Agricultural Research (EIAR), located in Debre Zeit, Ethiopia. Oropharyngeal swabs were collected from 117 randomly selected birds, and blood was taken from a subset of 73 of these birds. A combination of serological and molecular methods was used for detection of pathogens. For the first time in Ethiopia, we report the detection of variant infectious bronchitis virus (793B genotype), avian metapneumovirus subtype B and Mycoplasma synoviae in poultry. Mycoplasma gallisepticum was also found to be present; however, infectious laryngotracheitis virus was not detected by PCR. Newcastle disease virus (NDV) was not detected by PCR, but variable levels of anti-NDV HI antibody titres shows possible exposure to virulent strains or poor vaccine take, or both. For the burgeoning-intensive industry in Ethiopia, this study highlights several circulating infectious respiratory pathogens that can impact on poultry welfare and productivity

Genetic evidence of rotavirus in chicken from two localities in southwestern Nigeria

The presence of rotavirus in some poultry flocks in Abeokuta and Oyo was evaluated using the reverse transcription–polymerase chain reaction (RT-PCR) technique. A total of 49 fecal samples in form of cloacal swabs were collected from chickens and turkeys with age groups ranging between 5days and 43weeks. Six samples from diarrheic chicken aged 8 and 9 days old were positive for the virus, while others were negative. To our knowledge, this is the first study to report rotavirus infection in Nigerian poultry. It is recommended that epidemiological surveys be carried out to provide more data on rotavirus infection in poultry flocks in Nigeria

Seroprevalence of Marek’s Disease Virus antibody in some poultry flocks in southwestern Nigeria

This study reports a survey of Marek’s disease virus (MDV) antibody done in 21 selected poultry flocks in Lagos, Ogun and Oyo states of southwestern Nigeria. A total of 315 serum samples were examined using the Enzyme Linked Immunosorbent Assay (ELISA) technique. Marek’s disease virus antibody was present in 88.3% of the serum samples, while 11.7% were negative. Various ranges of flock mean optical densities (OD) were observed, with 8 flocks having a low (0.310-0.550 nm) level, medium (0.551-0.750 nm) level was observed in another 8 flocks, while high (0.751-0.950 nm) level was observed in 3 flocks. The OD level was very high (0.951-1.200 nm) in 2 flocks. Optical density levels also increased with age of the flocks. This shows that even after vaccination against Marek’s disease, not all flocks acquire over 90% positivity.Keywords: Poultry, chicken, Marek’s virus, antibody, Nigeri

Experimental reproduction of rotavirus and Salmonella pullorum gastroenteritis in broiler chicks

Numerous viruses, including astroviruses, reoviruses, rotaviruses, coronaviruses, and adenoviruses, have been implicated as causative agents of enteric disease. This is because they have been isolated from or identified in the intestines and intestinal contents of affected poultry flocks. Four experiments were conducted to reproduce enteritis in broiler birds using rotavirus and Salmonella pullorum. Fifty-two broiler birds were obtained and randomly divided into 4 groups. Group A chicks were inoculated with 1 X 106 pfu/ml of rotavirus, group B chicks were inoculated with 1 X 106 cfu/ml of Salmonella pullorum, group C chicks were inoculated with 1 X 106 pfu/ml of rotavirus and 1 X 106 cfu/ml of Salmonella pullorum, while group D birds were given 1ml of PBS alone. Birds in all groups were observed daily for clinical signs and the intestines were processed for histopathological evaluation. Diarrhea and depression were the major signs in chicks given any one of the inoculum. Histological changes were characterized by swollen villus tips and constricted villus bases, proliferation of enterocytes and necrotic villi. Significant growth retardation was observed in chicks given either rotavirus or Salmonella pullorum, but this effect was more pronounced in chicks given the combination of rotavirus and Salmonella pullorum. The present study reveals that oral inoculation of birds with rotavirus or rotavirus/Salmonella pullorum combination leads to diarrhoea and significant growth depression. It is thus important to continuously screen and prevent against organisms infecting the GIT for optimal performance of birds.Keywords: Broiler, Diarrhea, Growth depression, Rotavirus, Salmonella pulloru

Avian metapneumovirus subtype A in China and subtypes A and B in Nigeria

In order to detect and characterize avian metapneumovirus, organs or swabs were collected from 697 chicken and 110 turkeys from commercial farms in Southwestern Nigeria and from 107 chickens from live bird markets in Southeastern China. In Nigeria, 15% and 6% of the chicken and turkey samples, respectively, and 39% of the chicken samples from China, were positive for aMPV genome by PCR. The sequence of a 400 nt fragment of the attachment protein gene (G gene) revealed the presence of aMPV subtype A in both Nigeria and Southeastern China. Essentially identical subtype A viruses were found in both countries and were also previously reported from Brazil and the United Kingdom, suggesting a link between these countries or a common source of this subtype. In Nigeria, subtype B was also found, which may be a reflection of chicken importations from most major poultry-producing countries in Europe and Asia. In order to justify countermeasures, further studies are warranted to better understand the metapneumoviruses and their impact on poultry production.link_to_subscribed_fulltex