Seal gammaherpesviruses: identification, characterisation and epidemiology

Area of Science:

• Veterinary Virology
• Marine Mammal Health
• Herpesvirus Research

Background:

• Phocid herpesvirus type 2 (PhHV-2) is a gammaherpesvirus found in harbour seals.
• Limited information exists on PhHV-2 diversity and prevalence in different seal species.

Purpose of the Study:

• To isolate and characterize PhHV-2 from harbour seals and grey seals.
• To investigate the genetic and biological differences between PhHV-2 isolates.
• To determine the co-circulation of PhHV-2 between seal species.

Main Methods:

• Serological testing for PhHV-2 neutralising antibodies in harbour and grey seals.
• Isolation of PhHV-2 from peripheral blood mononuclear cells (PBMCs).
• Polymerase chain reaction (PCR) analysis and amino acid sequencing of viral isolates.
• Assessment of growth characteristics of different PhHV-2 strains.

Main Results:

• High prevalence of PhHV-2 antibodies detected in both harbour (38%) and grey seals (18%).
• PhHV-2 was successfully isolated from seropositive animals, with PCR confirming infection in a significant proportion of samples.
• Molecular and biological analyses revealed distinct PhHV-2 strains in harbour and grey seals.
• Evidence suggests potential co-circulation of these distinct gammaherpesviruses between the two species.

Conclusions:

• Harbour and grey seals harbor distinct but related gammaherpesviruses, tentatively identified as PhHV-2.
• The study highlights the importance of considering viral diversity in marine mammal populations.
• Findings suggest interspecies transmission of PhHV-2 may occur between harbour and grey seals.