Comparative computer-assisted sperm analysis in non-human primates.

BACKGROUND: Biomedical research has recently focused on developing new models of human disease by implementing genome-editing strategies in non-human primates (NHPs) to introduce relevant gene mutations. There is a need to establish objective semen evaluation methods to select sires for in vitro fertilization to perform germline editing in embryos. METHODS: Sperm motility kinematic parameters were evaluated using a computer-assisted semen analysis (CASA) instrument for rhesus macaques (Macaca mulatta), cynomolgus macaques (Macaca fascicularis), and common marmosets (Callithrix jacchus). RESULTS: Normative sperm kinematic parameters were established, revealing differences between marmosets and macaques. The impact of season on rhesus macaque sperm motility was modest, where changes in sperm motility related to season were dependent on the individual male. CONCLUSIONS: These data provide a baseline of normative kinematic parameters for three captive NHP species, in which implementation of CASA may serve as a tool to evaluate NHP semen quality.

Zika virus in rhesus macaque semen and reproductive tract tissues: a pilot study of acute infection†.

Although sexual transmission of Zika virus (ZIKV) is well-documented, the viral reservoir(s) in the male reproductive tract remains uncertain in humans and immune-intact animal models. We evaluated the presence of ZIKV in a rhesus macaque pilot study to determine persistence in semen, assess the impact of infection on sperm functional characteristics, and define the viral reservoir in the male reproductive tract. Five adult male rhesus monkeys were inoculated with 105 PFU of Asian-lineage ZIKV isolate PRVABC59, and two males were inoculated with the same dose of African-lineage ZIKV DAKAR41524. Viremia and viral RNA (vRNA) shedding in semen were monitored, and a cohort of animals were necropsied for tissue collection to assess tissue vRNA burden and histopathology. All animals exhibited viremia for limited periods (1-11 days); duration of shedding did not differ significantly between viral isolates. There were sporadic low levels of vRNA in the semen from some, but not all animals. Viral RNA levels in reproductive tract tissues were also modest and present in the epididymis in three of five cases, one case in the vas deferens, but not detected in testis, seminal vesicles or prostate. ZIKV infection did not impact semen motility parameters as assessed by computer-assisted sperm analysis. Despite some evidence of prolonged ZIKV RNA shedding in human semen and high tropism of ZIKV for male reproductive tract tissues in mice deficient in Type 1 interferon signaling, in the rhesus macaques assessed in this pilot study, we did not consistently find ZIKV RNA in the male reproductive tract.