Generation and evaluation of A2-expressing Lactococcus lactis live vaccines against Leishmania donovani in BALB/c mice

Abstract

Leishmaniasis is a parasitic disease affecting over 12 million individuals worldwide. As current treatments are insufficient, the development of an effective vaccine is a priority. This study generated and assessed the efficacy of Leishmania vaccines engineered from the non-colonizing, non-pathogenic Gram-positive bacterium Lactococcus lactis. A truncated, codon-optimized version of the A2 antigen from Leishmania donovani was engineered for expression in Lactococcus lactis in three different subcellular compartments: in the cytoplasm, secreted outside the cell or anchored to the cell wall. These three A2-expressing Lactococcus lactis strains were tested for their ability to generate A2-specific immune responses and as live vaccines against visceral Leishmania donovani infection in BALB/c mice. Subcutaneous immunization with live Lactococcus lactis expressing A2 anchored to the cell wall effectively induced high levels of antigen-specific serum antibodies. It was demonstrated that Lactococcus lactis-based vaccines are a feasible approach in the generation of live vaccines against leishmaniasis. The Lactococcus lactis strains generated in this study provide an excellent foundation for further studies on live bacterial vaccines against leishmaniasis and other pathogens.

Oral Administration of Recombinant Lactococcus lactis Expressing HSP65 and Tandemly Repeated P277 Reduces the Incidence of Type I Diabetes in Non-Obese Diabetic Mice

“…In addition, L. lactis is noninvasive and thus has less potential to trigger immune system hyper-activation or side effects from prolonged use [27], [28]. Currently, L. lactis -based vaccines have not been evaluated under clinical trials, however, successful vaccinations have been reported using L. lactis -based genetically modified micro-organisms (GMO) [29] bacterial vaccines against several diseases in mice model [14], [30], [31]. In the present study, we found that L. lactis vaccines via oral administration were well accepted by NOD mice.…”

Immunization against Leishmania major Infection Using LACK- and IL-12-Expressing Lactococcus lactis Induces Delay in Footpad Swelling

“…They showed that subcutaneous immunization with L. lactis expressing tetanus toxin fragment C (TTFC) anchored to the cell-wall was more immunogenic than immunization with bacteria expressing the antigen in the cytoplasm or secreted, and was able to provide better protection against lethal challenge. Additionally, our group previously showed that subcutaneous immunization with L. lactis expressing A2 anchored to the cell-wall induced the highest level of antigen-specific antibody titers compared to other expression strategies and reduced parasite burdens in L. donovani -challenged animals [29]. Therefore, we hypothesized that for subcutaneous immunization with L. lactis , the expression of the antigen anchored to the cell-wall would be the most immunogenic.…”

Making an anti-amastigote vaccine for visceral leishmaniasis: rational, update and perspectives

“…Protective immunity results in reduced lesion size and numbers of parasites in protected animals [73][74][75][76][77][78]. Given the impressive reductions in parasite burdens at the site of infection and in distant body sites, anti-A2 immune responses may act by promoting clearance of parasites instead of only preventing their dissemination.…”

“…Several pre-clinical tests, which included administration of A2 antigens either as recombinant protein associated to different adjuvants [73,74], DNA [75,76], attenuated nonreplicative viruses [30], non-pathogenic bacteria [77] or non-virulent parasites (L. tarentolae) [78], have provided evidence of the protective effect of vaccination in mice.…”