Prevalence and Association of Leishmania RNA Virus-1 (LRV-1) in Severe and Non-Severe Phenotypes of American Tegumentary Leishmaniasis from Peru

Abstract

Background: American tegumentary leishmaniasis (ATL) comprises a discrete set of clinical presentations of leishmaniasis endemic to Latin America and particularly Peru. Leishmania RNA virus-1 (LRV-1) is a double stranded RNA virus identified in 20-25% of the Leishmania Viannia complex, and is believed to be a predictive biomarker of severe ATL. Our objective was to determine the baseline prevalence of LRV-1 and associations with clinical phenotypes of ATL in patients from Peru. Methods & Materials: Banked clinical isolates of Leishmania Viannia spp. from patients residing in or traveling to Peru between 2012 and 2016 were species identified, by PCR, RFLP analysis, and Sanger sequencing, and screened for LRV-1 by real-time PCR. Patient isolates were stratified according to clinical phenotype: localized cutaneous leishmaniasis (LCL) was defined as “non-severe” ATL, whereas “severe ATL” was defined as mucosal or mucocutaneous leishmaniasis (ML/MCL); erythematous, purulent, or painful ulcers and/or lymphatic involvement (inflammatory ulcers); or multifocal/disseminated ulcers (≥4 in ≥2 anatomic sites). Proportions of LRV-1-positivity were calculated and compared across phenotypes. Results: Of 81 patients enrolled, 45(56%) and 36(44%) of ATL cases had the severe and non-severe phenotypes, respectively. Seventeen (38%) of 45 severe ATL cases and 13(36%) of 36 non-severe ATL cases were positive for LRV-1, respectively (p = 1.00). The severe phenotype was over-represented among older patients (median age 42 years vs. 30.5 years in non-severe ATL, p = 0.01), while LRV-1 was over-represented among younger patients (median age 28 years vs. 39 years in LRV-1 negative, p = 0.02). No difference in disease severity by sex (p = 0.12) or causative species (p = 0.057) was identified. Similarly, no difference in LRV-1 status was observed by sex (p = 1.00) or causative species (p = 0.45). LRV-1 copy number was greater in those with ML/MCL compared to those with all forms of CL (p = 0.04). Conclusion: A direct association between LRV-1 status and clinical phenotype was not demonstrated, however LRV-1 copy number was higher in patients with ML/MCL. Our findings suggest age as a contributing factor to disease severity. Given the likelihood of relapse in patients with severe ATL and associated risk of treatment failure, further elucidation of LRV-1's possible contribution to disease severity in ATL warrants further exploration.