| dc.description.abstract | Background: Virulence factors (VF) are endogenous molecules that often enhance the pathogenicity of an organism. The role of host age on the immunopathogenesis of leishmaniasis is poorly understood. Despite pediatric populations being frequent victims of leishmaniasis, few studies elucidate whether or not age-specific disease progression patterns exist, on a molecular level in the parasite, whereas clinical epidemiological studies have noted some differences in prognosis and presentation in limited cohorts. Our objective was to quantify known VF RNA transcript expression in clinical isolates, and compare this across age groups. Methods & Materials: Total cellular RNA was extracted from cultured promastigotes of Leishmania , cDNA was reverse transcribed, and qPCR assays were performed to determine transcript expression for: zinc-metalloproteinase ( gp63 ), cysteine proteinase B ( cpb ), mannose phosphate isomerase ( mpi ), and heat shock proteins 23, 70, 83 and 100 ( hsp23 , hsp70 , hsp83 and hsp100 ). Sub-categorical analysis was conducted on a per-gene and pooled basis, between two age groups: pediatric (<18 years), and adults (>19 years). Results: Four species isolated from 8 patients with cutaneous leishmaniasis are represented in this study: L. infantum (n = 1, 12.5%), L. tropica (n = 2, 25%), L. V. braziliensis (n = 1, 12.5%) and L. V. panamensis (n = 4, 50%). We did not observe differences in VF RNA transcript expression between pediatric and adult populations for the following: pooled VF (p = 0.68), cpb (p = 0.78), gp63 (p = 0.45), mpi (p = 1.00), hsp23 (p = 1.00), hsp70 (p = 0.57), hsp83 (p = 1.00), and hsp100 (p = 1.00). The same analyses were done for the four L. V. panamensis clinical isolates, with no differences in VF RNA transcript expression: pooled VF (p = 0.67), cpb (p = 1.00), gp63 (p = 1.00), mpi (p = 0.67), hsp23 (p = 0.67), hsp70 (p = 0.67), hsp83 (p = 1.00), and hsp100 (p = 1.00). Conclusion: Here we describe initial quantitative evidence that suggests host age may not be a substantial correlate of VF RNA transcript expression in clinical Leishmania isolates. We failed to elucidate VF RNA transcript expression as the biological underpinning of age-based phenotypic associations suggested by clinical and epidemiological studies. The potential existence of novel or more host-derived immunopathogenesis mechanisms, rather than parasite-specific VFs, may be influenced by age. | |
