Development of standard operating procedures to obtain longitudinal vaginal specimens from nulliparous rabbits as part of HIV vaccine mucosal immunogenicity studies

Abstract

The New Zealand white rabbit model ( Oryctolagus cuniculus) is widely used to test whether HIV vaccine candidates elicit systemic antibody responses; however, its use in mucosal immunology has not been fully exploited due to the difficulty in collecting mucosal specimens longitudinally and reproducibly. Here we describe feasible and non-feasible methods to collect vaginal and nasal specimens from nulliparous rabbits. Non-feasible methods were those resulting in poor reproducibility and considerable animal twitching during sampling, whereas feasible methods resulted in no animal twitching and potential for sampling reproducibility. Standard operating procedures (SOPs) were implemented to collect vaginal swabs yielding total IgA titres ranging from 12,500 to 312,500. Intranasal immunisation with a naked DNA vaccine encoding HIV gp140 elicited HIV envelope-specific IgA detectable in nasal but not in vaginal secretions. Our methods provide an alternative to reliably assess pre- and post-vaccination mucosal antibody titres longitudinally in rabbits as part of mucosal HIV vaccine immunogenicity studies.