Results of the final multivariate analysis (logistic regression with governorate as a random effect) of risk factors associated with the serological status of commercial poultry flocks regarding avian influenza virus (AIV) in Tunisia during the 2010–2011 outbreaks.

<p>Results of the final multivariate analysis (logistic regression with governorate as a random effect) of risk factors associated with the serological status of commercial poultry flocks regarding avian influenza virus (AIV) in Tunisia during the 2010–2011 outbreaks.</p

A linear relationship between threshold cycle and serially diluted DNA concentration or TCID50 values.

<p>PCR efficiency ((10^3.503−1)×100) was 99.87% as indicated by the slope (m = −3.503). The standard curve was generated from amplification of the H9 gene with each point represents the mean of the results from three determinations.</p

Map of the estimated between-flock AIV seroprevalence and number of commercial poultry flocks sampled by Tunisian governorates from October 2010 to May 2011.

<p>Map of the estimated between-flock AIV seroprevalence and number of commercial poultry flocks sampled by Tunisian governorates from October 2010 to May 2011.</p

Analysis of amino acid sequences of the HA and NA proteins of current Tunisian isolates.

<p>Analysis of amino acid sequences of the HA and NA proteins of current Tunisian isolates.</p

Results of the logistic regression screening of categorical risk factors associated with cELISA IA seropositivity in 624 commercial poultry flocks during the 2010–2011 outbreaks in Tunisia.

<p>Results of the logistic regression screening of categorical risk factors associated with cELISA IA seropositivity in 624 commercial poultry flocks during the 2010–2011 outbreaks in Tunisia.</p

Phylogenetic relationships of the HA (a) and NA (b) genes of 2010–2011 Tunisian strains (H9N2).

<p>Horizontal distances are proportional to the minimum number of nucleotide differences required to join nodes and sequences. Vertical distances are for spacing branches and labels. The phylogenetic trees were generated by using the neighbor-joining algorithm assessed by bootstrap analysis with 1,000 replications. Abbreviations used in virus designation are as follows: Av, avian; Ck, chicken; Dk, duck; gs, goose; Qu, quail; Tk, Turkey; Pa, parakeet. The in box strains are avian H9N2 Influenza viruses' isolates that were sequenced in the present study.</p

The between-flock AIV seroprevalence (mean proportion of poultry flocks positive regarding antibodies to AIV) in Tunisian governorates from October 2010 to May 2011.

<p>The between-flock AIV seroprevalence (mean proportion of poultry flocks positive regarding antibodies to AIV) in Tunisian governorates from October 2010 to May 2011.</p

cELISA results for detection of antibodies to influenza A virus NP in commercial chicken and turkey sera.

<p>(Result was defined as positive when % of competition is ≤45%, doubtful at 45–50% and negative ≥50% competition).</p

Pathogenicity of CEF cells to avian H9N2 influenza virus in the presence (CDEF) and absence (B) of trypsin.

<p>(A) mock cells. Arrows showed syncytia and plaque formations.</p