Comparative Evaluation of Lesion Development, Tissue Damage, and Cytokine Expression in Golden Hamsters (Mesocricetus auratus) Infected by Inocula with Different Leishmania (Viannia) braziliensis Concentrations

Abstract

The golden hamster (Mesocricetus auratus) is a susceptible model to Leishmania (Viannia) spp.; however, available studies employ different infection protocols, which account for clinical and pathological presentation differences. Herein, L. (V.) braziliensis preparations were standardized to contain 10 4 , 10 5 , or 10 6 parasites to determine an optimal inoculum that ensured cutaneous lesions without causing a disseminated infection in hamsters. Lesion development was followed for 105 days by size measurements, and skin, draining lymph node, spleen, and sera were investigated to check parasite load, spleen visceralization, cytokine expression, histopathological changes, and anti-Leishmania IgG levels. The lesion emergence time was inversely proportional to the parasite concentration in the inocula. Animals infected by 10 4 parasites presented nodular lesions, while those infected with 10 6 parasites often exhibited ulcerated lesions. The differences in the final lesion sizes were observed between 10 4 and 10 5 inocula or 10 4 and 10 6 inocula. High IFNG expression, anti-Leishmania IgG levels, and parasite load occurred independently of the inoculum used. A mild inflammatory skin involvement was observed in animals infected with 10 4 parasites, while extensive tissue damage and parasite spleen visceralization occurred with 10 5 and 10 6 parasites. These results indicate that inocula with different concentrations of parasites generate differences in the time of lesion emergence, clinical presentation, and systemic commitment, despite high and similar IFNG expression and parasite load. This suggests that a modulation in the immune response to different parasite numbers occurs in an early phase of the infection, which could dictate the establishment and magnitude of the chronic phase of the disease.

Development of real-time PCR assays for evaluation of immune response and parasite load in golden hamster (Mesocricetus auratus) infected by Leishmania (Viannia) braziliensis

“…The evaluation of the immunological markers mRNA levels in golden hamsters infected with L. ( V .) braziliensis were based on sequences of primers already described [ 11 , 18 , 25 , 26 ] or designed for this study, according to Table 1 . For real-time PCR assays, 2 μl cDNA (at 10 ng/μl) were used in a final reaction volume of 10 μl, with 5.0 μl of Power SYBR Green PCR Master Mix 2X (Life Technologies, CA, USA), 100 nM of forward and 100 nM of reverse primers (except for the IL-4 primers, where 200 nM of Forward and Reverse primers were used), in a ViiA7 Real-Time PCR System (Applied Biosystems, Foster City, CA, USA), in 384 well plates.…”

“…The golden hamster ( Mesocricetus auratus ) is the most susceptible model for the infection by species of the subgenus Viannia , reproducing many of the clinical and histopathological features observed in the human disease [ 8 – 10 ]. Furthermore, its outbred genetic background, which highlights individual characteristics, reproduces the heterogeneity of clinical outcomes observed in human CL [ 11 ]. Nevertheless, few studies on drugs [ 12 – 15 ] and vaccines [ 16 , 17 ] against CL are performed in the hamster model.…”

Propolis reduces Leishmania amazonensis-induced inflammation in the liver of BALB/c mice

“…However, in experimental infections with L. braziliensis, L. tropica, L. mexicana, L. major, and L. amazonensis, cases of migration to secondary organs differing from the site of infection have been described. These species were initially described as parasites with a unique tropism for skin and mucosa (Walton et al 1977; Barral et al 1986;Magill et al 1993;Mohareb et al 1996;Abreu-Silva et al 2004;Wilson et al 2005;Soliman 2006;Ribeiro-Romão et al 2014). In addition, L. amazonensis has been reported as an etiologic agent of human visceral leishmaniasis (Roberts et al 1989; Barral et al 1991).…”

Use of Optical Imaging Technology in the Validation of a New, Rapid, Cost-Effective Drug Screen as Part of a TieredIn VivoScreening Paradigm for Development of Drugs To Treat Cutaneous Leishmaniasis

“…Models of in vivo lesion (dorsal and footpad) cure using the BALB/c mouse and Golden Syrian hamster (GSH) with Leishmania spp. as a source of CL have been widely used to test the efficacies of antileishmanial drugs (4–10). Leishmania major infection triggers a strong Th2 response in BALB/c mice, which lack an early NK cell response and a Th1 type of response.…”