title: Risk factors and characteristics of low pathogenic avian influenza virus isolated from commercial poultry in Tunisia.
abstract: OBJECTIVE
  Estimate 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.
  
  
  METHODS
  This 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.
  
  
  RESULTS
  Out 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.
  
  
  CONCLUSIONS
  Our 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.
authors: University Tunis El Manar, Veterinary Microbiology Laboratory, Institut Pasteur de Tunis, Tunis- Belvédère, Tunisia.
authors: Wafa
authors: W
authors: Tombari
authors: Mathilde
authors: M
authors: Paul
authors: Jihene
authors: J
authors: Bettaieb
authors: Imen
authors: I
authors: Larbi
authors: Jihene
authors: J
authors: Nsiri
authors: Imen
authors: I
authors: Elbehi
authors: Latifa
authors: L
authors: Gribaa
authors: Abdeljelil
authors: A
authors: Ghram
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D002645:Chickens / Q000821:virology; D003132:Commerce; D004279:DNA, Viral / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D005814:Genes, Viral / Q000235:genetics; D005843:Geography; D005585:Influenza in Birds / Q000191:economics / Q000453:epidemiology* / Q000821:virology*; D016015:Logistic Models; D008969:Molecular Sequence Data; D015999:Multivariate Analysis; D009975:Orthomyxoviridae / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D010802:Phylogeny; D011200:Poultry / Q000821:virology*; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D014416:Tunisia / Q000453:epidemiology; D014422:Turkeys / Q000821:virology; D014764:Viral Proteins / Q000737:chemistry / Q000235:genetics
chemical_list: D000914:Antibodies, Viral; D004279:DNA, Viral; D014764:Viral Proteins