Differential replicative ability of clinical dengue virus isolates in an immunocompetent C57BL/6 mouse model

Abstract

BackgroundSeveral experimental animal models have been used to study the pathogenesis of dengue disease; however, most of the studies used laboratory-adapted viruses, which lack the virulence of viruses circulating in humans. The aim of this study was to analyze the ability of clinical Dengue virus (DENV) isolates (D2/BR/RP/RMB/09 and D3/BR/SL3/02) to infect immunocompetent C57BL/6 mice.MethodsTwo strategies of intraperitoneal infection, which were based on the concept of the antibody dependent enhancement phenomenon, were used. In one strategy, the animals were inoculated with macrophages infected in vitro with dengue viruses, which were incubated with enhancing antibodies, and in the other strategy, the animals were inoculated with a complex of enhancing antibodies and dengue viruses.ResultsThe D3/BR/SL3/08 isolate showed a higher ability of infection (virus RNA was more frequently detected in the serum and in several organs) in the experimental model compared to both the D2/BR/RP/RMB/2009 isolate and a laboratory adapted DENV-1 strain (Mochizuki strain), regardless of the infection strategy used. The main features of the D3/BR/SL3/08 isolate were its neuroinvasiveness and the induction of an extended period of viremia. Enhancing antibodies did not influence on the infection of animals when macrophages were used, but the level of viremia was increased when they were used as a complex with a D3/BR/SL3/02 isolate.DiscussionWe showed that DENV isolates could infect immunocompetent C57BL/6 mice, which have has been previously used to study some aspect of dengue disease when infected with laboratory adapted strains. DENV genome was detected in the same organs found in humans when autopsy and biopsy samples were analyzed, showing that C57BL/6 mice reproduce some aspects of the DENV tropism observed in humans. The main difference observed between the D3/BR/SL3/02 and D2/BR/RP/RMB/2009 clinical isolates was the neuroinvasive ability of the first one. Neuroinvasiveness has been described in some DENV infected cases and is common for other members of the Flavivirus genus.ConclusionsThese results suggest that C57BL/6 mice can be used as an experimental model to evaluate virulence differences among DENV clinical isolates.

CCR2 Plays a Protective Role in Rocio Virus–Induced Encephalitis by Promoting Macrophage Infiltration Into the Brain

“…Blood specimens were obtained from the retro-orbital region and collected in a tube containing 3.8% sodium citrate buffer [23]. Mice were perfused intracardially with 20 mL of 0.9% NaCl solution to remove blood from the tissues.…”

A murine model of dengue virus infection in suckling C57BL/6 and BALB/c mice

“…Newer models have recapitulated some aspects of disease in non‐IFN‐based immunodeficiencies or have used humanized mouse models 29 . Some aspects of primary infection, including enzymatic and biochemical alterations and tissue damage have been modeled in immunocompetent C57BL/6 mice infected with mouse adapted‐DENV and some clinical isolates 32‐35 . Another study documented increased vascular permeability and a platelet reduction in C57BL/6 mice infected with a DENV clinical isolate 36,37 .…”

Desenvolvimento de modelo experimental de infecção pelo vírus da dengue em camundongos.

“…As diferenças entre os grupos inoculados para os parâmetros avaliados foram determinadas por analise de Teste t, onde ** indica p < 0,01 em comparação ao grupo de animais controle. (BARROS et al, 2015;COSTA et al, 2011;PAES et al, 2005;RAJMANE et al, 2013;TAN et al, 2010;YAMANAKA;KONISHI, 2009). No entanto, as condições experimentais se mostraram distintas em função de diferentes variáveis, isto é, isolado ou cepa utilizada, linhagens de animais imunodeficientes, quantidades de vírus inoculada ou, até mesmo, a incorporação de adjuvantes (BARROS et al, 2015;GUABIRABA, 2013;PAES et al, 2005;RAJMANE et al, 2013;TAN et al, 2010;WILLIAMS et al, 2009;YAMANAKA;KONISHI, 2009).…”

“…É importante salientar que a escolha pelo uso de camundongos neonatos (2 dias de vida) se baseou no fato de que esses animais apresentam um sistema imunológico em desenvolvimento e, portanto, seriam mais susceptíveis à infecção (HUANG et al, 2000). Esses resultados indicaram que, mesmo possuindo alta virulência para camundongos imunocompetentes, o isolado JHA1 não se mostrou capaz de se replicar e infectar nos animais após administração pela via i.p.. Esse resultado vai de acordo a relatos anteriores que mostram a resistência de camundongos imunocompetentes à infecção pelo DENV quando administrados por vias parenterais (BARROS et al, 2015;GUABIRABA, 2013;JOHNSON;ROEHRIG, 1999;PLUMMER;SHRESTA, 2014;WILLIAMS et al, 2009). No entanto, esse resultado conflita com a descrição inicial do isolado JHA1 quando testado pela via i.c.…”

“…Uma segunda abordagem experimental feita no sentido de desenvolvermos um modelo experimental alternativo para infecção para DENV baseou-se no uso de camundongos adultos inoculados com o isolado JHA1 pela via i.v.. Nesses ensaios trabalhamos com quantidades de vírus semelhantes àquelas inoculadas pelo vetor (em torno de 10 4 a 10 6 UFP/ por picada) durante o processo de infecção em humanos (BARROS et al, 2015). Os resultados obtidos indicaram aumento nos níveis de LDH em camundongos inoculados pela via i.v.…”