Characteristics of cyprinid herpesvirus 3 in different phases of infection: implications for disease transmission and control.
Koi herpesvirus disease (KHVD) is an emerging and highly contagious viral disease of koi and common carp (Cyprinus carpio), causing mass mortalities and huge economic losses to the carp aquaculture industry. The disease has spread rapidly to 28 countries worldwide. However, mechanisms of koi herpesvirus (species Cyprinid herpesvirus 3; CyHV-3) transmission remain unclear. A potential experimental model of CyHV-3 infection in carp was used to characterise CyHV-3 in different phases of infection and to demonstrate that CyHV-3 persists in survivor fish and has the capacity to reactivate and transmit the disease to healthy fish. During acute infection, which occurred when fish were maintained at 22°C, viral genes were abundantly expressed and infectious virus was produced in association with tissue damage, clinical disease and mortality. In fish maintained at a lower temperature (11°C), viral DNA was present but viral gene expression was absent or greatly restricted, infectious virus was not recovered and there was no evidence of disease. Productive replication was re-initiated following an increase in water temperature to 22°C, resulting in 45% mortality. Shedding of reactivated virus killed 75% of cohabitating naïve fish, suggesting a potential risk for disease transmission.
CSIRO Animal, Food and Health Sciences, Australian Animal Health Laboratory, Geelong, VIC 3220, Australia; Fish Health Research Laboratory, Centre for Aquaculture Research and Development, Jakarta 12540, Indonesia.
Agus
A
Sunarto
CSIRO Animal, Food and Health Sciences, Australian Animal Health Laboratory, Geelong, VIC 3220, Australia. Electronic address: Kenneth.Mccoll@csiro.au.
Kenneth A
KA
McColl
CSIRO Animal, Food and Health Sciences, Australian Animal Health Laboratory, Geelong, VIC 3220, Australia.
Mark St J
MS
Crane
Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA.
Karel A
KA
Schat
Centre for Virus Research, Westmead Millennium Institute and University of Sydney, Sydney 2145, Australia.
Barry
B
Slobedman
School of Biological Sciences, The University of Queensland, Brisbane, QLD 4072, Australia.
Andrew C
AC
Barnes
CSIRO Animal, Food and Health Sciences, Australian Animal Health Laboratory, Geelong, VIC 3220, Australia.
Peter J
PJ
Walker
D000818:Animals; D002347:Carps / Q000821:virology*; D002353:Carrier State / Q000662:veterinary / Q000821:virology; D006564:Herpesviridae / Q000502:physiology* / Q000528:radiation effects; D006566:Herpesviridae Infections / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D016019:Survival Analysis; D013696:Temperature; D014775:Virus Activation; D014779:Virus Replication / Q000528:radiation effects*; D017201:Virus Shedding
Cyprinid herpesvirus 3 (CyHV-3); Disease transmission; Gene expression; Koi herpesvirus; Latent; Persistent