Comparative analysis of protein profiles of wild virulent (E156) and aroA-htrA double deletion mutant vaccine strain (S30) of Salmonella enterica subsp. enterica serovar Abortusequi under in vivo and in vitro growth conditions.

In the present study, cell lysate and cell supernatant of the both strains i.e., virulent wild type (E156) and mutant (S30) vaccine strains of Salmonella enterica subspecies enterica serovar Abortusequi (S. Abortusequi), grown under varied in vivo and in vitro conditions were subjected to SDS PAGE and western blotting (using rabbit hyperimmune serum). Variation in growth conditions did not have any significant effect on expression of different proteins. SDS PAGE of E156 and S30 cell lysate (CL) revealed 26 and 28 bands, respectively with 3 prominent proteins of 71, 46 and 42 kDa in cell lysate of E 156 and 4 prominent proteins 71, 65, 46 and 40 kDa in S30 strain. The cell supernatant (CS) from both the strains, subjected to SDS PAGE, exhibited similarity in protein profile among these strains, however three bands of 65, 53 and 40 kDa were more prominent in CS preparation of S30, whereas a 56 kDa protein was prominent in CS of E156. Western blotting of E156 and S30 revealed 3 unique proteins of 65, 53 and 40 kDa present in CS preparation of S30 strains which could be used for differentiation of mutant and wild strains and also in development of test for differentiating vaccinated animals from naturally infected.

Partial purification and cytotoxic effects of Salmonella proteinous moieties on chick embryo fibroblasts.

Salmonella enterica serovars, viz., S. Weltevreden, S. Typhimurium, S. Gallinarum and S. Bareilly were treated with cephotaxime to release of intracellular proteins. The cephotaxime extract (CE) was salt precipitated with ammonium sulphate (45-70%) and dialyzed, and denoted as precipitated dialyzed proteins (PDP). Further, both CE and PDP of Salmonella Weltevreden and PDP of rest of the serovars were subjected to gel filtration using Sephacryl S-200HR. Different fractions along with CE and PDP were studied for their cytotoxicity using chicken embryo fibroblast (CEF). All the CE and PDP exerted cytotoxic effects, characterized by rounding, detachment, shrinkage and clumping of cells with syncytia formation. Also, the fractions eluted in the 2nd and 3rd peaks through Sephacryl S-200HR column invariably had cytotoxic activity. It was concluded that in place of Vero cell line, CEF cells could also be used to test cytotoxicity.