RESUMO
One of the major causes of morbidity and mortality in tropical and subtropical regions is Dengue viral infection. This virus belongs to family flaviviridae comprising of four antigenically distinct serotypes DENV 1 - 4. A small number of studies conducted in North Eastern (NE) Region of India reported Dengue cases in Assam, Meghalaya, Nagaland, Manipur and Arunachal Pradesh. However, no studies have been conducted in the state of Tripura, with regard to pattern of Dengue viral infection and its circulating serotypes. Therefore, this study was undertaken to identify the serotypes circulating in Tripura. MethodsPatients with acute febrile illness were tested for detecting Dengue viral infection by MAC ELISA and / or NS1 detection test at Viral Research and Diagnostic Laboratory (VRDL), of a tertiary care centre in Tripura for a period of 3 years. All NS1 positive samples were further tested for presence of viral RNA by Reverse Transcriptase –PCR (RT - PCR) and serotyping was done using serotype specific primers. ResultsA total of 2515 acute febrile cases seen over a period of 3 years from 2014 to 2017 was tested for Dengue virus infection by serology. Out of 2515 of cases, 405 cases tested for NS1 antigen, where 10.61 % (43 / 405) was NS1 positive. The remaining 2110 cases were tested for IgM antibody MAC ELISA and 15.68 % (331 / 2110) was MAC ELISA positive. Out of all NS1 antigen positive cases 34.88 % of PCR positive and serotype characterisation showed DENV - 1 was predominant serotype followed by DENV - 2 and DENV - 4 respectively. ConclusionsThere is a rising trend of Dengue virus infection in Tripura with circulation of multiple serotypes. Moreover, cocirculation of multiple serotypes is a risk to the emergence of recombinant strains and also heterotypic infection in the near future might lead to development of DHF and DSS. Hence, molecular characterization of circulating serotypes may be helpful in addressing the probabilities of Dengue outbreak and possibilities of complications.
RESUMO
In experimental visceral leishmaniasis the causative obligate protozoan parasite, L. donovani invades and multiplies inside of macrophages, one of the sentries of the mammalian immune system. The initial host-parasite interaction between the Leishmania promastigote and the macrophage takes place at the plasma membrane interface. To trace any possible interaction between Toll-like receptor 2 (TLR2) and CC chemokine receptor 5 (CCR5) during early Leishmania-macrophage interactions, it was observed that the expression of both TLR2 and CCR5 were significantly increased, along with their recruitment to the lipid raft. TLR2 silencing attenuates CCR5 expression and restricts L. donovani infection, indicating a regulatory role of TLR2 and CCR5 during infection. Silencing of CCR5 and TLR2 markedly reduced the number of intracellular parasites in macrophages by host protective cytokine responses, while raft disruption using β-MCD affected TLR2/CCR5 cross-talk and resulted in a significant reduction in parasite invasion. In vivo RNA interference of TLR2 and CCR5 using shRNA plasmids rendered protection in Leishmania donovani-infected mice. Thus, this study for the first time demonstrates the importance of TLR2/CCR5 crosstalk as a significant determinant of Leishmania donovani entry in host macrophages.