Characterization of some immunogenic proteins and their potential as vaccine candidates

Abstract

Treating regimen against intracellular pathogens has been a challenge to scientific community because of their inhabitant priorities. Those infections not only infect range of host cells but also escape from circulating antibodies. Being intracellular, it is very difficult to completely remove them from the host system and require specific dosage regimen for their treatment. Beside, most antibiotics are also marred with hurdles like side effects, cost, availability in the market, schedule of administration. Moreover emergence of multidrug resistance strains due to overuse of antibiotics especially in case of tuberculosis and other intracellular pathogens has restricted their use. Extensive drug resistance is a menace to be handled by available antibiotics which thus makes the treatment more complex and complicated, keeping into consideration the fact that prevention is a preferred option over treatment, it is an urgent requirement to develop vaccine against intracellular pathogens. Generation of protective immunity against many pathogens requires fine adjustment between humoral and cell mediated immunity. Circulating antibodies play crucial role in the elimination of extracellular infections, however majority of intracellular infections (e.g. L. newlinemonocytogenes, M. tuberculosis, malaria, leishmaniasis, candidiasis etc.) require generation of CD8+ cytotoxic T-cells (CTL) in conjunction to strong CD4+ T-helper cells (Th) because such pathogens adapt intracellular parasitism as a strategy to avoid recognition by antibodies. Vaccine development against intracellular pathogens is very complicated as intracellular pathogens adapt different mechanisms to protect themselves from host immune system, some of them being capable to modulate the immune system e.g. inhibition of antibody production (L.monocytogenes, S. typhimurium, N. meningitis), interfere with antigen processing by antigen presenting cells (APCs) (L. monocytogenes, S. typhimurium), inhibition of lymphocyte proliferation (H. pylori, M. leprae, L. monocytogenes