BACKGROUND: Zika virus (ZIKV) infection has been associated with prolonged viral 
excretion in human semen and causes testicular atrophy and infertility in 
10-week-old immunodeficient mice.
METHODS: Male IFNAR-/- mice, knockout for type I interferon receptor, were 
immunized with GLS-5700, a deoxyribonucleic acid-based vaccine, before a 
subcutaneous ZIKV challenge with 6 × 105 plaque-forming units at 13 weeks of 
age. On day 28 postinfection, testes and epididymides were collected in some 
mice for histological and functional analyses, whereas others were mated with 
naive female wild-type C57BL/6J.
RESULTS: Although all mice challenged with ZIKV developed viremia, most of them 
were asymptomatic, showed no weight loss, and survived infection. On day 28 
postinfection, none of the unvaccinated, infected mice (9 of 9) exhibited 
abnormal spermatozoa counts or motility. However, 33% (3 of 9) and 36% (4 of 11) 
of mated males from this group were infertile, from 2 independent studies. 
Contrarily, males from the noninfected and the vaccinated, infected groups were 
all fertile. On days 75 and 207 postinfection, partial recovery of fertility was 
observed in 66% (2 of 3) of the previously infertile males.
CONCLUSIONS: This study reports the effects of ZIKV infection on male fertility 
in a sublethal, immunodeficient mouse model and the efficacy of GLS-5700 
vaccination in preventing male infertility.