Immunogenic protein profiling of pathogenic Escherichia coli strains isolated from infants with diarrhea in Quetta Balochistan

Abstract

Escherichia coli (E. coli) is a widespread bacterial species that comprise a broad variety of strains and can be highly pathogenic often. Diarrhea caused by E. coli pathotypes is a leading public health problem in underdeveloped countries such as Pakistan. Five different diarrheagenic E. coli pathotypes (Enterohaemorrhagic, Enteropathogenic, Enteroaggregative, Enteroinvasive and Enterotoxigenic E. coli) were isolated from 200 samples of diarrheal children in Quetta, Pakistan. Total-cell protein profiles of all the strains isolated were resolved via SDS-Polyacrylamide Gel Electrophoresis (PAGE). More than 15 protein bands were found ranging from 15 kDa to 153 kDa in size. A dendrogram plot explained the relatedness of the pathotypes amongst them. The protein bands of 70 and 15 kDa, analyzed through GelAnalyzer 2010a© were found common among all the isolated pathotypes. Purified bands of these two proteins (70 and 15 kDa) from the gel were injected in experimental mice groups for immunization purposes. During immunogenicity tests, the mice that were immunized with 70 and 15 kDa proteins stayed alive for seven days despite subsequently being challenged with the E. coli pathotypes, while higher mortality 80% were observed in the non-immunized control group. Upon the postmortem it was revealed that all the vital organs were covered by the E. coli strains injected for challenge studies. The immunized mice and control mice sera subjected to the Agar Gel Immunodiffusion assay (AGID) test for antibody/antigen reaction were found positive for antibodies presence. The exploration of immunogenic proteins among all the prevalent pathotypes can be a breakthrough in the development of a combined, effective, and safe vaccine. Further investigation of these immunogenic proteins would be of great importance for future immunization endeavors.