Prevalence and clinical significance of herpesvirus infection in populations of Australian marsupials
Stalder, K, Vaz, PK, Gilkerson, JR, Baker, R, Whiteley, P, Ficorilli, N, Tatarczuch, L, Portas, T, Skogvold, K, Anderson, GA & Devlin, JM 2015, PloS One, vol. 10, no. 7, p. e0133807.
To date, molecular classification of herpesviruses in marsupial species has been limited. In this study, the presence of herpesviruses in several Australian marsupial species, including koalas, was identified and assessed for risk factors seen during herpesvirus infection. It was found that the presence of Chlamydia pecorum DNA in koalas was highly associated with the presence of herpesvirus DNA, which could suggest a co-infection dynamic.
Polymerase chain reaction (PCR) using conserved primers for herpesvirus, found that there was 33.3% prevalence of Phascolarctid herpesvirus (PhaHV) 1 and 2 in koalas, with one koala observed to have both PhaHV-1 and PhaHV-2 infections. Serological analyses with antibodies targeting macropodid herpesvirus (MaHV) 1 and 2 did not identify MaHV infection in koalas. Further comparison of epidemiological factors against presence of herpesviruses found that koalas carrying herpesvirus DNA had a significant association of concurrent infection with C. pecorum.
An explanation for the potential co-infection dynamic of herpesvirus and C. pecorum in koalas could be that each pathogen acts as a beneficial companion to the other during the transmission process. It is also possible that a C. pecorum infection could have increased the burden on the koala immune system, allowing for reactivation of a latent herpesvirus infection (or vice-versa). Both pathogens could also act synergistically for the propagation of clinical disease in the koala.
While not discussed in-depth with regard to koalas specifically, it was reported in this study that C. pecorum infection could be a significant risk factor for herpesvirus infection or vice versa. As C. pecorum infection has been established as a significant health issue in koalas, this information will prove useful for further studies to investigate the impacts a potential herpesvirus-C. pecorum association could have on the health of koalas.
Summarised by Daniel Chew
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