Prospecção de marcadores imunológicos e caracterização molecular do vírus Chikungunya em pacientes atendidos no SUS/Alagoas

Abstract

Chikungunya virus (CHIKV) is an arboviral disease characterized by onset of abrupt fever, rash and severe arthralgia. In Brazil, since the first report of autochthonous transmission in 2014, there has been a huge increase in the number of cases, however, little is known about its immunopathology and the immune response against the virus. Thus, the present study aimed to characterize the genotype of CHIKV strains detected during the outbreak in Alagoas in 2016 and to evaluate the levels of cytokines and chemokines in serum samples from patients infected with CHIKV in the acute phase of the disease. For this purpose, samples confirmed by real-time RT-PCR during the outbreak of 2016 were gently provided by the Laboratório Central de Saúde Pública de Alagoas (LACEN / AL) and some of these were selected for DNA sequencing (n=11) of the partial E1 genome region followed by phylogenetic analysis. In addition, serum levels of cytokines (IL-1β, IL-2, IL-4, IL-6, IL-12p70, IL-10, IFN-α, IFN-γ and TNF-α) and chemokines (IL-8, MIG, MCP-1, IP-10 and RANTES) were evaluated by CBA flow cytometry in CHIKV positive samples up to 5 days post-onset of symptoms (n=36) and compared to healthy blood donors samples (n=23). In this study, all analyzed samples were grouped in the ECSA CHIKV genotype branch. The patient's immune profile was characterized by an acute inflammatory response predominantly mediated by IL-6, IL-8, IP-10, MCP-1 and MIG including an increase of IFN-α that has a powerful antiviral activity. Interestingly, an increase in IFN-γ as well as MIG and IP-10 which are both IFN gamma-induced chemokines were also detected. Additionally, high levels of analytes associated to disease severity and high viral loads in previous studies such as IL-6, MIG and MCP-1 were detected in serum samples. In conclusion, this study reports the ECSA lineage in the outbreak of 2016 in the State of Alagoas and detected IFN-γ, IFN-α, IL-6, IL-8, MCP-1, IP-10 and MIG as the main biomarkers in the acute phase of CHIKV infection. These results can contribute to understand the CHIKV-immune system interaction and immunopathology as well as discovery of acute phase biomarkers that could be associated with prognosis and morbidity of this infectious disease.