Immunological changes in response to herpesvirus infection in abalone Haliotis laevigata and Haliotis rubra hybrids

► Infection by abalone herpesvirus causes short term changes in cellular immunity. ► Haemocyte numbers increase at the subclinical stage of infection. ► At the clinical stage, haemocyte numbers and superoxide decrease in moribund abalone. ► Healthy subclinically infected abalone were found to have elevated cellular immunity. ► Humoural antiviral activity was not affected by exposure to AbHV.