Vaccination with a Leishmania infantum HSP70-II null mutant confers long-term protective immunity against Leishmania major infection in two mice models

Background: the immunization with genetically attenuated leishmania cell lines has been associated to the induction of memory and effector t cell responses against leishmania able to control subsequent challenges. a leishmania infantum null mutant for the hsp70-ii genes has been described,possessing a non-virulent phenotype. methodology/principal findings: the l. infantum attenuated parasites (liδhsp70-ii) were inoculated in balb/c (intravenously and subcutaneously) and c57bl/6 (subcutaneously) mice. an asymptomatic infection was generated and parasites diminished progressively to become undetectable in most of the analyzed organs. however,inoculation resulted in the long-term induction of parasite specific ifn-γ responses able to control the disease caused by a challenge of l. major infective promastigotes. balb/c susceptible mice showed very low lesion development and a drastic decrease in parasite burdens in the lymph nodes draining the site of infection and internal organs. c57bl/6 mice did not show clinical manifestation of disease,correlated to the rapid migration of leishmania specific ifn-γ producing t cells to the site of infection. conclusion/significance: inoculation of the liδhsp70-ii attenuated line activates mammalian immune system for inducing moderate pro-inflammatory responses. these responses are able to confer long-term protection in mice against the infection of l. major virulent parasites. © 2017 solana et al.