Detection of Riemerellosis in Ducks by gyrB Gene Based Polymerase Chain Reaction

Abstract

The new duck disease or riemerellosis is predominantly a disease of ducks caused by a gram negative organism Riemerella anatipestifer. The present study was focused on the standardisation of gyrB gene based PCR for its investigation in Kerala. Evolutionary rate of gyrB gene created by mutation is faster than any other protein-coding genes. Hence, the gyrB gene was targeted for primer designing and by gradient PCR optimum conditions were arrived, which yielded an amplicon with 162 bp size. Throat swabs were collected from 60 apparently healthy ducks and 56 throat swabs revealed positive reaction by gyrB PCR whereas the bacteria were isolated from only four cases. The throat swabs of experimentally infected ducklings were found to be negative by gyrB PCR, but the liver and heart blood yielded positive amplicons and also the bacteria was isolated in pure culture. The results revealed that gyrB PCR was more accurate, sensitive and specific than the conventional culturing methods.