SAMIR DAS* S.V.S. MALIK, SAMEER SHRIVASTAVA, PRADEEP GANDHALE, SATISH KUMAR, SHABU SHOUKAT, DURGA P. DAS, S.B. BARBUDDHE AND D.B. RAWOOL
Abstract
A multiplex PCR (mPCR) targeting virulence gene(s) of Listeria spp. i.e., Internalin C (inlC), Internalin J (inlJ) and Listeriolysin O (hlyA) in case of Listeria monocytogenes and inlC in case of Listeria ivanovii was developed and evaluated on standard strains of Listeria spp. as well as isolates (25) of Listeria spp. with known biochemical and pathogenicity profiles based on other in vitro and in-vivo pathogenicity test with an ultimate view to evaluate this mPCR for rapid and reliable identification and pathogenicity testing of listeria isolates was done. Out of many known virulence marker, listeriolysin-O encoded by hlyA gene is till date a well recognized one with few errors; here in this study InlC and InlJ genes were also studied in conjunction with hlyA to strengthen the existing hlyA marker. The mPCR showed presence of inlC gene in majority but not in all virulent strains of pathogenic listeriae, however, it was also detected in some non-pathogenic L. monocytogenes strains. The same trend had been seen in, inlJ also, which revealed although these genes are linked to virulence but may not be an essential a full proof virulence marker for Listeria spp. However, its combination with other more specific virulence marker(s) need to be evaluated on known positive and negative Listeria strains with known pathogen city profiles on a large number of Listeria isolates of various kind before drawing any final conclusion.