Chikungunya virus infection in BALB/c and ICR mouse models

Abstract

Chikungunya virus (CHIKV) infection is an emerging or re-emerging infectious disease found in several countries. The ecology of this virus involves humans, reservoir animals, and mosquito vectors. Two experiments were conducted in this study. Blood samples were collected and tested for CHIKV infection by using immunocytochemistry (ICC) staining and reverse transcription polymerase chain reaction (RT-PCR). For the first experiment, BALB/c mice were inoculated with 106.3 CID50/mouse. Mean CHIKV titers in the BALB/c mice were 103.3, 101.5, 102.3, and 102.3 CID50/ml of serum on day 1 to day 4 post inoculation (PI), respectively. For the second experiment, there were two groups of ICR mice. For the first group or immunosuppressed ICR group, the mice were injected with 100 g of dexamethasone for 14 days. For the second group or control ICR group, the mice were injected with 0.1 ml of normal saline for 14 days. All mice were then inoculated with 106.3 CID50/mouse. For the immunosuppressed ICR group, mean CHIKV titers in the mice were 102.7, 103.0, 104.7, 103.5, 102.8, 103.0, and 102.5 CID50/ml of serum on day 1 to day 7 PI, respectively. For the control ICR group, mean CHIKV titers in the mice were 102.0, 101.0, 102.4, 103.5, 103.0, 102.7, and 101.5 CID50/ml of serum on day 1 to day 7 PI, respectively. The virus titers were quite similar in both groups of mice and no signs of illness were found in any of the CHIKV-infected BALB/c and ICR mice. In addition, it is necessary to study CHIKV infection in wild mice in nature to indicate the roles of wild mice in the epidemiology of CHIKV in Thailand.