Shiga toxin-producing Escherichia coli (STEC), Enteropathogenic E. coli (EPEC), and Enterotoxigenic E. coli (ETEC) make up an important group of pathogens causing major animal and public health concerns worldwide. The aim of this study was to determine the prevalence of different pathotypes of E. coli in captive wildlife. We analyzed 314 fresh fecal samples from captive wildlife, 30 stool swabs from animal caretakers, and 26 feed and water samples collected from various zoological gardens and enclosures in India for the isolation of E. coli , followed by pathotyping by multiplex PCR. The overall occurrence rate of E. coli was 74.05% (274/370). The 274 E. coli isolates were pathotyped by multiplex PCR targeting 6 genes. Of them, 5.83% were pathotyped as EPEC, 4.74% as STEC, and 1.09% as ETEC. The 16S rRNA genes from the selected isolates were amplified, sequenced, and a phylogenetic tree was constructed. The phylogenetic tree exhibited indiscriminate genetic profiling and some isolates from captive wild animals had 100% genetic identity with isolates from caretakers, suggesting that captive wildlife may serve as a reservoir for infection in humans and vice-versa. The present study demonstrates for the first time the prevalence of these E. coli pathotypes in captive wildlife in India. Our study suggests that atypical EPEC strains are more frequent than typical EPEC strains in captive wildlife. Discovering the implications of the prevalence of these pathotypes in wildlife conservation is a challenging topic to be addressed by further investigations.

Outer membrane vesicles (OMVs) contain biologically active proteins, lipoolysaccharide (LPS), periplasmic and membranebound proteins and are known to perform diverse biological functions. OMVs from Brucella abortus S19 were isolated and characterized by transmission electron microscopy (TEM), SDS-PAGE and immunoreactivity was investigated by western blotting. On TEM, bilayered spherical structures of 50-200 nm were observed. SDS-PAGE of OMVs revealed approximate bands size of 82 kDa, 68 kDa, 38 kDa, 32 kDa, 29 kDa and 18 kDa. Western blot analysis of OMVs revealed a dominant immunoreactive band of 38 kDa that correspond to some major outer membrane proteins. Humoral immune response was measured by indirect ELISA which showed that OMV specific antibodies were detected from 7 th day post immunization (DPI) onwards and showed a rising trend up to 35 th DPI. Cell mediated immune (CMI) response against OMVs as evidenced by the proliferation of splenocytes have also been observed. Thus OMVs were found to possess immunogenic proteins which had potential to induce both humoral as well as cell mediated immunity. After correlating this immune response with protection it has been concluded that OMV can be used as one of the vaccine candidate against brucellosis.

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