Zika Virus Infection in Dexamethasone-immunosuppressed Mice Demonstrating Disseminated Infection with Multi-organ Involvement Including Orchitis Effectively Treated by Recombinant Type I Interferons

Chan, Jasper Fuk-Woo; Zhang, Anna Jinxia; Chan, Chris Chung-Sing; Yip, Cyril Chik-Yan; Mak, Winger Wing-Nga; Zhu, Houshun; Poon, Vincent Kwok-Man; Tee, Kah-Meng; Zhu, Zheng; Cai, Jian-Piao; Tsang, Jessica Oi-Ling; Chik, Kenn Ka-Heng; Yin, Feifei; Chan, Kwok-Hung; Kok, Kin-Hang; Jin, Dong-Yan; Au-Yeung, Rex Kwok-Him; Yuen, Kwok-Yung

A clinical isolate of ZIKV (Puerto Rico strain PRVABC59) was kindly provided by Brandy Russell and Barbara Johnson, Centers for Disease Control and Prevention, USA. The virus was amplified by three additional passages in Vero cells (ATCC) in minimum essential medium (MEM) supplemented with 1% fetal calf serum and 100 units/ml penicillin plus 100 μg/ml streptomycin to make working stocks of the virus. For virus titration, aliquots of ZIKV were applied on confluent Vero cells in 96well plates for 50% tissue culture infectious dose (TCID 50 ) assay as we previously described with slight modifications (Zhou et al., 2014) . Briefly, serial 10-fold dilutions of ZIKV were inoculated in a Vero cell monolayer in quadruplicate and cultured in penicillin/streptomycinsupplemented MEM. The plates were observed for cytopathic effect for 5 days. Viral titer was calculated with the Reed and Münch endpoint method. One TCID 50 was interpreted as the amount of virus that causes cytopathic effect in 50% of inoculated wells.