Detection of Virulence Associated Genes of Pasteurella multocida Isolated from Pig Farms of India

Abstract

Progressive atrophic rhinitis and pneumonic pasteurellosis caused by Pasteurella multocida are recognized as economically important diseases of swine having a significant impact on pig industry throughout the world. A total of 87 (8.40%) P. multocida isolates were recovered from 1035 samples collected from diseased and apparently healthy pigs. P. multocida was the fourth most frequent pathogenic bacterium recovered from the samples after Escherichia coli, Streptococcus species and Staphylococcus aureus. P. multocida isolates were examined for capsule synthesis genes (capA, B, D, E and F) and eleven virulence associated genes (ompH, oma87, ompA, plpB, ptfA, pfhA, tonB, hgbA, nanB, nanH and toxA) by PCR. Of 87 P. multocida isolates, 54.02% isolates belonged to capsular type A, 43.67% to capsular type D, 2.29% isolates were untypeable whereas none of these isolates belonged to capsular type B, E and F. Virulence associated genes investigated were present in more than 90% of P. multocida isolates, except for the genes ptfA, pfhA and toxA. The study revealed a strong positive association of genes such as toxA (P<0.05), oma87 (P<0.05) and ptfA (P<0.01) with diseased animals in comparison with healthy animals. These findings provide novel insights into the epidemiological characteristics of porcine P. multocida isolates circulating in Indian piggeries and can form the basis for devising control strategy against Pasteurella infection in pigs.