Examining the effect of transgenerational immune priming against HaHV-1 in the abalone

Abalone ( Haliotis spp.) are a high-valued molluscan species that is under threat by the deadly and re-emergent viral pathogen, Haliotid herpesvirus (HaHV-1). HaHV-1 and its associated disease, Abalone Viral Ganglioneuritis (AVG), have devastated wild and farmed abalone species in China, Taiwan, and Australia with no available treatments or preventatives. Abalone do not possess an adaptive immune system and therefore rely on their innate immune response for protection. Previous work has identified that abalone can be significantly protected against HaHV-1 infection if directly immune primed with the non-specific dsRNA immune stimulant, poly(I:C) prior to viral challenge, however, this is not feasible for use by aquaculture facilities that house millions of abalone. This current study investigated the effect of maternal transgenerational immune priming (TGIP) against HaHV-1 infection in blacklip, greenlip and hybrid offspring aged 6–12 months. We found that priming female broodstock with poly(I:C) 8-weeks, 4-weeks or 3-days prior to spawning did not provide progeny with protection against HaHV-1 upon reaching 12-months of age. Additionally, the offspring produced from primed mothers were significantly smaller (weight and length) when compared to those produced from unprimed mothers. Despite this result, this study showed that the handling and immune priming of female broodstock did not negatively affect spawning and emphasised the inherent resistance of abalone <1 year old to HaHV-1 infection. This work provides a first look into a potential farm-deployable anti-viral strategy against HaHV-1 for the abalone industry.