Preclinical validation of a second generation leishmanization vaccine against vector transmitted fatal visceral leishmaniasis

Nakhasi, H. L.; DEY, R.; Gannavaram, S.; Karmakar, S.; Bhattacharya, P.; Ismail, N.; Satoskar, A.; Volpedo, G.; Oliveira, L. F.; Oristian, J.; Meneses, C.; Valenzuela, J. G.; Kamhawi, S.; Zhang, W. W.; Matlashewski, G.; Hamano, S.; Satoskar, M.; Satoskar, S.; Sastry, R. M.; Kaviraj, S.; Singh, S.; Singh, K. P.; Das, S.; Das, P.; Mondal, A.; Pandey, K.

doi:10.1101/2020.11.18.388553

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bioRxiv · 10.1101/2020.11.18.388553

Preclinical validation of a second generation leishmanization vaccine against vector transmitted fatal visceral leishmaniasis

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Abstract

Visceral Leishmaniasis (VL) is fatal if untreated. There is no licensed vaccine available against human leishmaniasis. We recently demonstrated protection in mice against L. major infection using a CRISPR genome edited attenuated Leishmania major strain (LmCen-/-). Here, as a pre-clinical step, we evaluated the protective efficacy of LmCen-/- against VL induced by sand fly transmitted Leishmania donovani in hamsters. Intradermal immunization of hamsters with LmCen-/- did not develop any lesion; while still priming a pro-inflammatory immune response. When challenged with L. donovani either by intradermal needle injection or by infected sand flies, LmCen-/--immunized hamsters were protected, not showing spleen or liver pathology averting VL fatality compared to control animals. Spleen cells from LmCen-/- immunized and infected sand fly challenged hamsters produced significantly higher Th1-associated cytokines and chemokines including IFN-{gamma} and TNF-, and significantly reduced expression of the anti-inflammatory cytokines IL-10 and IL-21, compared to non-immunized challenged animals. We further developed a GLP-grade LmCen-/- which showed equal protection as laboratory-grade LmCen-/- parasites in hamsters. Importantly, GLP-grade LmCen-/- parasites also induced a proinflammatory immune response in the PBMCs isolated from healthy people living in non-endemic and endemic for VL as well as cured VL people living in endemic region. Together, this study demonstrates that the LmCen-/- parasites are safe and efficacious against VL and it is a strong candidate vaccine to be tested in a human clinical trial.

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Nakhasi, H. L., DEY, R., Gannavaram, S., Karmakar, S., Bhattacharya, P., Ismail, N., Satoskar, A., Volpedo, G., Oliveira, L. F., Oristian, J., Meneses, C., Valenzuela, J. G., Kamhawi, S., Zhang, W. W., Matlashewski, G., Hamano, S., Satoskar, M., Satoskar, S., Sastry, R. M., Kaviraj, S., Singh, S., Singh, K. P., Das, S., Das, P., Mondal, A., Pandey, K.. 2020-11-20. Preclinical validation of a second generation leishmanization vaccine against vector transmitted fatal visceral leishmaniasis. https://doi.org/10.1101/2020.11.18.388553

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