Preventative Vaccines for Zika Virus Outbreak: Preliminary Evaluation

Kim, Eun; Erdos, Geza; Huang, Shaohua; Kenniston, Thomas; Falo, Louis D.; Gambotto, Andrea

To evaluate passive protection by maternal antibody, pups were obtained by mating non-immunized males with immunized females at three weeks following booster vaccination. Pups were challenged intraperitoneally (i.p.) with ZIKV DAKAR41542 (10 5 pfu/50 μl) at seven days after birth. Two non-challenged pups from each litter were used as a control and bled at 28 days after birth to determine passive maternal antibodies. The physical condition of the pups was observed and their body weights were measured daily for 15 days. Exhibiting N10% loss of body weight was defined as onset of disease. In addition to mice that were found dead, mice with weight loss exceeding 25% of their highest body weight were euthanized and recorded as dead. Severity of neurological signs was scored as described previously (Yoshii et al., 2014) . Signs of paralysis and loss of balance associated with viral infection were scored as 0 (absent), 1 (present), or 2 (severe). Scoring for paralysis was assigned as follows: 0, normal; 1, dragging limbs or inversion of dorsum pedis; and 2, complete paralysis and no spontaneous movement. Scoring for loss of balance was assigned as follows: 0, normal; 1, leaning of head or trunk posture to one side; and 2, inability to retain posture and falling to one side or a circling movement to one side. Total scores were quantified and were expressed as means ± the standard errors of the mean.