Desenvolvimento de um modelo experimental de infecção por vírus Ilhéus (ILHV) em camundongos e delineamento de estratégias terapêuticas

Author(s)

Ana Carolina Carvalho

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2024-09-24

Examining board members

Rafael Elias Marques; José Luiz Proença Módena; Artur Torres Cordeiro; Renata Sesti Costa; Marília de Freitas Calmon

• Advisor: Rafael Elias Marques

Abstract

Neglected Tropical Diseases (NTDs) represent a global health problem for which lack of knowledge, preventive and therapeutic strategies and diagnostic methods are major concerns. There is a constant risk of urbanization and emergence of NTDs and the occurrence of outbreaks and epidemics, as seen recently with Chikungunya (CHIKV, 2014) and Zika (ZIKV, 2015) viruses. Ilhéus virus (ILHV) is a neglected arthropod-borne virus (arbovirus) of the family Flaviviridae, genus Orthoflavivirus, comprising a variety of other species relevant to human health, such as Yellow Fever (YFV), Dengue (DENV), Zika (ZIKV), and Saint-Louis Encephalitis virus (SLEV). Mayaro virus (MAYV), another neglected arbovirus, belongs to the Togaviridae family, Alphavirus genus, which also contains other medically relevant viruses, such as Chikungunya (CHIKV) and Ross River virus (RRV). Both of these arboviruses circulate in the Caribbean, Central and South America, infecting several vertebrate hosts, including humans. Infection by ILHV or MAYV can cause a non-specific acute febrile illness characterized by weakness, fever, myalgia and headache, but severe ILHV cases can progress to neurological illness, while severe MAYV cases may evolve into chronic arthritogenic disease. No approved vaccines or treatments are available against these viruses. Study models are imperative for understanding the pathogenesis of neglected diseases, and for developing and testing candidate treatments. In this work, we established experimental models for study of ILHV and MAYV infections, aiming at compound testing and disease characterization in murine models. Type I interferon receptor-deficient mice (IFNAR-/-) are susceptible to ILHV and MAYV infection via peripheral routes of inoculation at concentrations as low as 10 plaque forming units (PFU), indicating a central role for type I interferon response (IFN-I) in protection against ILHV and MAYV. The infection is acute, leading to the death of all animals within 4 days post-infection (4 days p.i.). ILHV and MAYV were detected at high concentrations in the brain, liver, spleen and serum of infected mice on day 3 p.i., correlating with the peak of symptoms. High viral load in the observed organs was predictive of death, along with weight loss and ocular inflammation. In vitro, ILHV was able to infect, replicate and cause death in several cell lines, with sharp increase in viral load, presence of cytopathic effect (CPE) and decrease in cell viability at 72 hours post-infection (72h p.i.) in all cell lines tested. Among the compounds tested against ILHV infection, treatment with the nucleoside analogue 2'-C-methylcytidine (2'CMC) was able to reduce viral load and improve cell viability in vitro, while also delayed disease onset and prolonged survival in vivo in IFNAR-/- mice. Lymphocytes and macrophage are greatly reduced in the MAYV IFNAR-/- model, while proinflammatory mediators CXCL1, CCL5, IFN-? and IL-1ß are upregulated. Detailed features of MAYV-induced paw inflammation were observed using a semi-automated phase–contrast X-ray microtomography technique we developed at a synchrotron source. The experimental models developed in this work offer a platform for drug testing and study of ILHV and MAYV infections that can greatly contribute to the advancement of knowledge about disease and development of therapeutic and diagnostic strategies (AU)

• FAPESP's process: 18/02993-0 - Development of the first experimental model of Ilheus Virus (ILHV) infection in mice and design of therapeutic strategies
• Grantee: Ana Carolina de Carvalho
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)