Exacerbated leishmaniasis caused by a viral endosymbiont can be prevented by immunization with Its viral capsid

Recent studies have shown that a cytoplasmic virus called Leishmaniavirus (LRV) is present in some Leishmania species and acts as a potent innate immunogen, aggravating lesional inflammation and development in mice. In humans, the presence of LRV in Leishmania guyanensis and in L. braziliensis was significantly correlated with poor treatment response and symptomatic relapse. So far, no clinical effort has used LRV for prophylactic purposes. In this context, we designed an original vaccine strategy that targeted LRV nested in Leishmania parasites to prevent virus-related complications. To this end, C57BL/6 mice were immunized with a recombinant LRV1 Leishmania guyanensis viral capsid polypeptide formulated with a T helper 1-polarizing adjuvant. LRV1-vaccinated mice had significant reduction in lesion size and parasite load when subsequently challenged with LRV1+ Leishmania guyanensis parasites. The protection conferred by this immunization could be reproduced in naïve mice via T-cell transfer from vaccinated mice but not by serum transfer. The induction of LRV1 specific T cells secreting IFN-γ was confirmed in vaccinated mice and provided strong evidence that LRV1-specific protection arose via a cell mediated immune response against the LRV1 capsid. Our studies suggest that immunization with LRV1 capsid could be of a preventive benefit in mitigating the elevated pathology associated with LRV1 bearing Leishmania infections and possibly avoiding symptomatic relapses after an initial treatment. This novel anti-endosymbiotic vaccine strategy could be exploited to control other infectious diseases, as similar viral infections are largely prevalent across pathogenic pathogens and could consequently open new vaccine opportunities

Mya arenaria - an ancient invader of the North Sea coast

Mya arenaria currently occupies a wide geographical range in the northern hemisphere, on both coasts of the Atlantic as well as on the Pacific east coast. Some authors claim it also occurs on the Pacific west coast. The species originated in the Pacific during the Miocene and was already present on both Atlantic coasts in the Pliocene. However, it died out on the east coasts of the Pacific and the Atlantic during glaciation of the Pleistocene. With the aid of man it was reintroduced to the North Sea some 400-700 years ago and to the East Pacific last century. In the 1960Žs it was also introduced to the Black Sea. Mya arenaria invaded new habitats by different modes: 1) natural range expansion 2) intentional as plantings 3) unintentional as a ballast species 4) unintentional as a byproduct of oyster transplants. Properties that may favor its wide range of distribution and invading success are: high fecundity; planktonic dispersal stages and life stages that lend itself to unintentional transport by humans; a broad spectrum of habitat and food preference; tolerance of a wide range of environmental conditions such as salinity and temperature; longevity and perhaps relatively large size