Analysis of the Presence of Anti-Viral Innate Immune Pathways in the Abalone

Abstract

Our understanding of the specificities of innate immune protection against viral pathogens in non-model invertebrate species is limited, and comparative immunological approaches may offer opportunities to protect agriculturally significant species such as abalone, against viral threats. Haliotid herpesvirus (HaHV-1) is a re-emerging viral pathogen of abalone, and has a high mortality rate in the dominant wild and farmed species in Australia, the Australian greenlip abalone (Haliotis laevigata), the black lip (Haliotis Rubra) and a hybrid of the two. To gain a better understanding of the antiviral immune system counterparts of Australian abalone, gene mining strategies and domain analysis of the recently released H. laevigata draft genome was performed, with comparisons made to the better studied mollusc, the oyster (Crassostrea gigas). Significant divergence in members of the TLR, cytosolic RNA/DNA and RNA interference signalling pathways was observed between the two molluscs, with the oyster more closely reflecting that of the mammalian immune response. Interestingly, a homolog for the antiviral RNA sensing adaptor protein Mitochondrial anti-viral-signalling protein was absent in H. laevigata, as well as the 4 other abalone protein databases currently available, despite the presence of a RIG-I homolog. Additionally, STING, a member of the dsDNA sensing pathway was absent in H. laevigata, as well as 2 other abalone species, however is present in the oyster genome, and two additional abalone species (Haliotis rufescens, Haliotis discus hannai).This work provides a better understanding of the key features of the abalone antiviral innate immune signalling system and may provide much needed information towards the development of anti-viral strategies in these animals.

Keywords: abalone, innate immunity, interferon, HaHV-1, pattern recognition receptors