Asian Research Thesis Index

Abstract

In this research Salmonella species were isolated from animal and human enteric sources from different veterinary and human hospitals in Faisalabad, Punjab, Pakistan. These species were further characterized by different morphological and biochemical techniques. The protein profiling of all ten strains through Sodium Dodecyl Sulphate Polyacrylamide Gel Electrophoresis (SDS-PAGE) revealed similarities and differences among the whole cell proteins of the ten isolates. The ten Salmonella species were identified and were confirmed through Polymerase Chain Reaction (PCR) by amplification of the 16S rRNA gene. Furthermore, sequencing of the amplicons confirmed all ten isolates as Salmonella strains. The antigenic cross-reactivity was found maximum between the HB1 (strain isolated from honey bee) antiserum and its antigen with an antibody titer of 1:128, while the HB1 antiserum showed a titer range of 1:8 to 1:64, when cross reacted with the remaining nine strains. On the basis of the highest Geometric mean titer (GMT) shown by the antiserum of the HB1 antigen, it was selected as the best candidate for a cross-reactive live Salmonella oral antigen. Moreover, the HB1 anitgen was used a live oral antigen (1×1010CFU/ml) in a safety test in rabbits and proved to be avirulent with no clinical symptoms of disease. During the animal trials three different oral doses of the HB1 live oral antigen were evaluated in four different rabbits groups (R1, R2, R3 and R4). The dose number 2 of 0.5ml (two drops orally and repeated after one week) in rabbits exhibited a cumulative mean titer of 49.7 measured by indirect haemagglutination which was better than the single (two drops orally once) and triple dose (two drops and repeated after alternate days for three times) 33 and 43. Results of the challenge protection test (four groups of rabbits infected with LD50 of S. Typhimurium ATCC 14028) also validated the efficacy of the double dose of the HB1 live vaccine, with the highest survival percentage. Results of this study lay the foundation for a potential cross reactive live oral Salmonella vaccine, which has showed to be immunogenic in an animal model.

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