Cyprinid herpesvirus 3 as a potential biological control agent for carp (Cyprinus carpio) in Australia: susceptibility of non-target species.

Carp (Cyprinus carpio L.) is a pest species in Australian waterways, and cyprinid herpesvirus 3 (CyHV-3) is being considered as a potential biological control (biocontrol) agent. An important consideration for any such agent is its target specificity. In this study, the susceptibility to CyHV-3 of a range of non-target species (NTS) was tested. The NTS were as follows: 13 native Australian, and one introduced, fish species; a lamprey species; a crustacean; two native amphibian species (tadpole and mature stages); two native reptilian species; chickens; and laboratory mice. Animals were exposed to 100-1000 times the approximate minimum amount of CyHV-3 required to cause disease in carp by intraperitoneal and/or bath challenge, and then examined clinically each day over the course of 28 days post-challenge. There were no clinical signs, mortalities or histological evidence consistent with a viral infection in a wide taxonomic range of NTS. Furthermore, there was no molecular evidence of infection with CyHV-3, and, in particular, all RT-PCRs for viral mRNA were negative. As a consequence, the results encourage further investigation of CyHV-3 as a potential biocontrol agent that is specific for carp.

Isolation and characterization of koi herpesvirus (KHV) from Indonesia: identification of a new genetic lineage.

Koi herpesvirus (KHV) is the aetiological agent of an emerging disease (KHVD) associated with mass mortalities in koi and common carp and reported from at least 30 countries. We report the first isolation of KHV from koi and common carp in Indonesia and initial characterization of the isolates. Clinical signs, histopathology and virion morphology are similar to those of isolates from other countries. Phylogenetic analyses using the thymidine kinase gene amplified from each isolate and from carp tissue samples collected from KHVD outbreaks throughout Indonesia indicated that the Indonesian isolates are more closely related to the Asian than the European KHV lineage. Sequence analysis of two other variable regions between ORF29 and ORF31 (marker I) and near the start of ORF 133 (marker II) indicated that all Indonesian isolates displayed a marker I allele (I(++)) previously identified only in isolates of the Asian lineage. However, in the marker II region, all Indonesian isolates displayed the II(-) allele, which has been reported previously only amongst isolates of the European lineage, and nine of these displayed a mixed genotype (II(+)II(-)). The I(++)II(-) genotype has not been reported previously and appears to represent a new intermediate lineage that may have emerged in Indonesia.

Managing the koi herpesvirus disease outbreak in Indonesia and the lessons learned.

In 2002, the suspected koi herpesvirus (KHV) outbreak in Indonesia was investigated by an International Emergency Disease Control Task Force organized by NACA immediately following a request for assistance by the Government of Indonesia. The Task Force gained immediate support from ACIAR, AAHRI, FAO, CENTEX-Thailand, INTERVET, Stirling University, and the University of California. The Task Force findings revealed the involvement of an infectious agent, an analogy with KHV outbreaks, its introduction through fish importation and its spread into other areas through fish movement. A number of actions taken by the Government of Indonesia included temporary restrictions, through a Ministry Circular, on the movement of koi and common carps, intensive information dissemination, emergency notification to the OIE, and early warning to neighbouring countries. FAO immediately responded by providing an emergency technical assistance project to improve Indonesia's national capacity to respond to the carp disease epizootic. Recognizing the significance of and necessity for: (a) enhancing regional and international cooperation;(b) improving awareness of emerging disease epizootics and improving diagnostic capabilities at both national and regional levels;(c) proactive reporting of serious disease outbreaks as a mechanism for early warning;(d) detailed documentation of outbreak scenarios;(e) emergency preparedness;(f) empowering farmers to manage disease and other risks; and (g) strong national commitment from concerned authorities are some of the important lessons learned. Despite the intense efforts, the spread of KHV did not stop and continued to affect other countries such as Japan, China, the Taiwan Province of the Republic of China, and most recently Thailand. All relevant stakeholders cannot afford to be complacent and we need innovative responses to current and future disease challenges. The lessons learned in managing the Indonesian KHV outbreak as well as lessons from past disease epizootics will hopefully assist us in improving preparedness and responses to similar events when they occur in the future.