THE 1994 PLAGUE EPIDEMIC OF INDIA - MOLECULAR DIAGNOSIS AND CHARACTERIZATION OF YERSINIA-PESTIS ISOLATES FROM SURAT AND BEED

PCR analysis of formalin-fixed human autopsy tissues, rodent tissues, fleas and bacterial isolates from pneumonic patients from the 1991 pla gue epidemic confirmed the presence of the f1 and pla genes of Yersini a pestis in these samples, Several Y. pestis isolates from the epidemi c areas were studied in respect of their plasmid profile, expression o f FI antigen and ribotype pattern, All the three plasmids known to be associated with virulence were present in the Surat isolates of Y. pes tis. Presence of the F1 antigen, clasically used for diagnosis of Y. p estis infection, was demonstrated by immunoblotting. All the Indian is olates from the 1994 epidemic showed an identical ribotype profile, Th is profile, however, was different from those of Y. pestis isolates te sted from other regions of the world. Upon digestion with EcoRI and Ec oRV, and probing with E. coli 16S and 23S rRNA genes, DNA from these Y . pestis isolates gave two distinct profiles which, taken together, su ggest that the present Indian isolates represent a new ribotype. The p resence of Y. pestis signature genes in 5 out of 7 fleas collected fro m rodents in the affected areas, and the occurrence of the same riboty pe in the Y. pestis isolates from domestic rodents, sylvatic rodents a nd the patients are strongly indicative of a clonal origin of this Ind ian strain and an epidemiological linkage among wild rodents, domestic rats and humans in the epidemic area.