A virus in a parasite in a human

The protozoan parasite Leishmania, transmitted to humans by the bite of a sandfly, may cause disfiguring skin lesions. A virus within the parasite appears to increase the risk of treatment failure with anti-leishmania drugs. A double-stranded RNA virus was found over 20 years ago to infect different species of Leishmania, with up to 50% of clinical isolates infected. Leishmaniavirus (LRV) causes a chronic infection with little effect on the parasite. In mouse models, infection of Leishmania with LRV is associated with increased parasite replication and disease severity. The double-stranded RNA genome of LRV appears to be sensed by the mammalian innate immune system, leading to overproduction of cytokines and a hyper-inflammatory response. Similarly, the dsRNA of Trichomonas vaginalis virus is also sensed by the innate immune system, leading to inflammatory complications. Two independent studies have been done to assess the consequence of LRV infection in human cases of leishmaniasis. In one study, presence of LRV was determined in Leishmania braziliensis isolated from 97 patients in Peru and Bolivia. The patients were treated with pentavalent antimonials or amphotericin B, and the outcome was determined as ‘cured’ or ‘failure’. Thirty-two (33%) Leishmania isolates were found to contain LRV.   Treatment failed in 33% of the patients (18 of 54). There were fewer drug failures in the LRV negative isolates (9 of 37, 24%) than in the LRV positive isola...
Source: virology blog - Category: Virology Authors: Tags: Basic virology Information antimonial drug failure dsRNA leishmania Leishmania virus LRV parasite pentamidine protozoa viral Source Type: blogs