In situ hybridization revealed wide distribution of Haliotid herpesvirus 1 in infected small abalone, Haliotis diversicolor supertexta

Abstract

Ganglioneuritis was the primary pathologic change in infected abalone associated with Haliotid herpesvirus 1 (HaHV-1) infection, which eventually became known as abalone viral ganglioneuritis (AVG). However, the distribution of HaHV-1 in the other tissues and organs of infected abalone has not been systemically investigated. In the present study, the distribution of HaHV-1-CN2003 variant in different organs of small abalone, Haliotis diversicolor supertexta, collected at seven different time points post experimental infection, was investigated with histopathological examination and in situ hybridization (ISH) of HaHV-1 DNA. ISH signals were first observed in pedal ganglia at 48 h post injection, and were consistently observed in this tissue of challenged abalone. At the same time, increased cellularity accompanied by ISH signals was observed in some peripheral ganglia of mantle and kidney. At the end of infection period, lesions and co-localized ISH signals in infiltrated cells were detected occasionally in the mantle and hepatopancreas. Transmission electron microscope analysis revealed the presence of herpes-like viral particles in haemocyte nuclei of infected abalone. Our results indicated that, although HaHV-1-CN2003 was primarily neurotropic, it could infect other tissues including haemocytes.