Risk Factors and Characteristics of Low Pathogenic Avian Influenza Virus Isolated from Commercial Poultry in Tunisia

Abstract

ObjectiveEstimate the seroprevalence of influenza A virus in various commercial poultry farms and evaluate specific risk factors as well as analyze their genetic nature using molecular assays.Materials and MethodsThis report summarizes the findings of a national survey realized from October 2010 to May 2011 on 800 flocks in 20 governorates. Serum samples were screened for the presence of specific influenza virus antibodies using cELISA test. Additionally, swab samples were tested by real time and conventional RT-PCR and compared with results obtained by others assays. Phylogenetic and genetic analyses of the glycoproteins were established for some strains.ResultsOut of the 800 chicken and turkey flocks tested by cELISA, 223 showed positive anti-NP antibodies (28.7%, 95% CI: 25.6–32.1). Significantly higher seroprevalence was found among the coastal areas compared to inland and during the autumn and winter. Broiler flocks showed significantly lower seroprevalence than layers and broiler breeders. The influenza virus infection prevalence increased after the laying phase among layer flocks. In addition, AIV seropositivity was significantly associated with low biosecurity measures. The Ag EIA and rRT-PCR tests revealed significantly higher numbers of AI positive samples as compared to cell cultures or egg inoculation. All new strains were subtyped as H9N2 by real time and conventional RT-PCR. Drift mutations, addition or deletion of glycosylation sites were likely to have occurred in the HA and NA glycoproteins of Tunisian strains resulting in multiple new amino acid substitutions. This fact may reflect different evolutionary pressures affecting these glycoproteins. The role of these newly detected substitutions should be tested.ConclusionOur findings highlight the potential risk of AIV to avian health. Strict enforcement of biosecurity measures and possible vaccination of all poultry flocks with continuous monitoring of poultry stations may ensure reduction of AIV prevalence and avoid emergence of more pathogenic strains.

Evidence of Antibodies to H5 Subtype Avian Influenza Virus in Commercial Layer Farms in Jos, Nigeria

“…Also, the overall sero prevalence recorded in this study is higher than that (28.7%) reported by Tombari et al (2013) in a study conducted in commercial poultry farms in Tunisia. However, the sero prevalence recorded on LGA bases; Jos North (30%), and Jos South (34%) Nigeria was lower, than that recorded in same study by Tombari et al (2013) in Tunisia where they reported a prevalence of 47.7% in Tunis, 45.7% in Nebeul, and 41.3% for Sfax.…”

Mesenchymal stromal cell treatment prevents H9N2 avian influenza virus-induced acute lung injury in mice

“…Although the H9N2 avian virus subtype is generally not highly pathogenic for avian species, it has been associated with severe morbidity and mortality in poultry following coinfection with other pathogens [11, 12]. Recent findings indicate that the H5N1 viruses responsible for severe human disease contain genetic rearrangements that include several genes from obtained avian H9N2 viruses [13].…”

Vaccine Efficacy Against a New Avian Influenza (H9N2) Field Isolate from the Middle East (Serology and Challenge Studies)

“…The prevalence of AIV H9N2 infection varies between countries in the Middle East. For example, it was reported to be 40.6% in broilers in Iran (6), 28.7% in different poultry species in Tunisia (20), and 71% in broiler-breeders in Jordan (3).…”