Evaluation of Vigna subterranea seed Extract as Possible Adjuvant for Typhoid Fever Vaccine

Typhoid fever is an essential communicable disease that is endemic in developing countries characterised by poor water supply, sanitary conditions and increasing population. Vaccination with the Salmonella typhi (ST) vaccine is an effective control measure. The two currently licensed ST vaccines are saddled with a lot of drawbacks which can be overcomed by the addition of adjuvant. Vigna substerranea (VS) ethanolic extract was evaluated as a possible adjuvant to ST vaccine. Mice were vaccinated with typhoid vaccine followed by daily weight measurement, and enumeration of microbial colony counts post-vaccination ST challenge. The blood culture results showed that mice group that received our formulated vaccine had the lowest microbial load (82.2±29.72) colony forming units (CFU) following microbial challenge, the mice body weight assessment results also emphasize this as the mice in this treatment group had an uninterrupted healthy growth. Further, from our results VS extract demonstrated a relative inability to function as effective adjuvant to the ST vaccine since the microbial load in this group (vaccine + VS extract) was high (152.3±47.67) hence the ineffectiveness of combining both agents.