Vaccines have been implemented for more than two centuries and have saved millions of lives, which is one of the most outstanding inventions in medicine. The concept of vaccine was conceived two centuries ago by the English physician Edward Jenner, “the father of immunology”. He had initiated the first protective vaccine against smallpox using live cowpox virus in 1798. Many effective vaccines ...

Live attenuated vaccines are adept in stimulating protective immunity. Methods for generating such vaccines have largely adopted strategies used with Salmonella enterica. Yet, when similar strategies were tested in other gram-negative bacteria, the virulence factors or genes responsible to incapacitate Salmonella often failed in providing the desired outcome. Consequently, conventional live vac...