As long as KHV enters the fish’s habitat, there is a good chance for the fish to get infected. However, a small proportion of the infected fish doesn’t fall ill and show symptoms. There are two likely explanations. First, the infected fish may have a good immune system against the virus and stay healthy. However, they can only survive from low-level infection at the permissive temperature. Second, the environment is not suitable for KHV propagation. The most critical condition for KHV breeding is water temperature. As there is slight difference among various reports, the permissive temperature for KHV is from 18°C to 28°C. This is probably the reason why most of the KHV outbreaks have happened in spring and autumn. Out of the permissive temperature, then the virus is suggested to stay dormant (latent) in its host cell for a period of time. Such a period of time could be at least 200 days at 12°C. Dishonet el al. also suggest that koi herpesviurs could persist in fish body, based on his finding that KHV-infected cells became “healthy” after the temperature was elevated to 30°C, but low levels of virus infection was shown to be maintained this way for 30 days. Notably, virus infection was reactivated after the temperature was switched to permissive temperature.
Bibliography
Dishon Arnon, Davidovich Maya, Ilouze Maya, and Kotler Moshe (2007), Persistence of cyprinid herpesvirus 3 in infected cultured carp cells. Journal of Virology, vol.81, no. 9, 4828-4836
Gilad O., Yun S., Zagmutt-Vergara F.J., Leutenegger C.M., Bercovier H., Hedrick R.P. (2004), Concentrations of a Koi herpesvirus (KHV) in tissues of experimentally infected Cyprinus carpio koi as assessed by real-time TaqMan PCR. Dis Aquat Org, vol. 60(3), 179–187
Gray W.L., Mullis L., LaPatra S.E., Groff J.M., and Goodwin A. (2002), Detection of koi herpesvirus DNA in tissues of infected fish. Journal of Fish Diseases, vol. 25, 171-178
Haenen O.L.M., Way K., Bergmann S.M., Ariel E. (2004), The emergence of koi herpesvirus and its significance to European aquaculture. Bull Eur Assoc Fish Patho, vol. 24, 293–307
Hartman K.H., Yanong R.P.E., Pouder D.B., Petty B.D. Francis-Floyd R., and Riggs A.C. (2004). Koi herpesvirus (KHV) disease, Fact sheet VM-149, Extension service, Institute of Food and Agricultural Sciences, University of Florida 2004
Ilouze M., Dishon A., and Kotler M. (2006), Characterization of a novel virus causing a lethal disease in carp and koi. Microbiology and Molecular Biology Review, vol.70(1), 147-156
Perelberg A., Ilouze M., Kotler M., and Steinitz M. 2008), Antibody response and resistance of Cyprinus carpio immunized with cyprinid herpes virus3 (CyHV-3). Vaccine, vol 26, 3750-3756
Pokorova D., Vesely T., Piackova V., Reschova S., and Hulova J. (2005), Current knowledge on koi herpesvirus (KHV): a review. Veterinary medicine-Czech, vol. 50(4), 139-147
Soliman H., and El-Matbouli M. (2009), Immunocapture and direct binding loop mediated isothermal amplification simplify molecular diagnosis of Cyprinid herpsvirus-3. Journal Virological Methods, vol. 162(1-2), 91-95
St-Hilaire S., Beevers N., Way K., Le Deuff R. M., Martin P., and Joiner C. (2005), Reactivation of koi herpesviurs infections in common carp Cyprinus carpio. Diseases of Aquatic Organisms, vol. 67, 15-23
Tuesday, March 23, 2010
Friday, March 19, 2010
How do fish get infected with KHV?
As you already know that the KHV disease is caused by a virus; therefore, a contact with the virus is required for infection. According to reports available, there are a variety of sources for KHV spreading.
Figure 2: The sources for KHV spreading
A. Infected fish: As long as a fish is infected, no matter if the fish is showing symptoms and if the viruses are small in number, KHV can ruthlessly spread out. KHV was presumed to invade vulnerable fish through gills, because viral DNA is firstly detected in gills in many cases. Yet, Costes et al. proclaimed that KHV is transmitted by a “skin-to-skin” mode when infected fish rubbed other individuals or objects. Uninfected fish can also get infected by pecking skin lesions off or droppings from infected fish.
B. Carriers: Researchers applied various detection methods to support that KHV has a wider range of host besides koi and common carp. Goldfish (Carrassius auratus), Crucian carp (Carassius carassius), grass carp (Ctenopharyngodon idellus), and tench (Tinca tinca), seemed to carry and spread KHV, although all appear not to be affected KHV.
C. Water and mud: KHV remains infectious in water and mud for at least 4 hours and up to three months in a water body according to the report by Minamoto et al. in 2008. Water from the Yura River which had a KHV outbreak in one section was collected for examination. High levels of KHV were still detected after 3 months.
D. Other media: Anything, such as a net or a filter, which had contact with the virus, could possibly transmit the virus.
Bibliography
Costes B., Sta;om Raj V., Michael B., Fournier G., Thirion M., Gillet L., Mast J., Lieffrig F., Bremont M., Vanderplasschen A. (2009), The major portal of entry of koi herpesvirus in Cyprinus carpio. Journal of Virology, vol. 83 no. 7, 2819-2830
El-Matbouli M., Saleh M., and Soliman H. (2007), Detection of cyprinid herpesviurs type 3 in goldfish cohabiting with CyHV-3-infected koi carp (Cyprinus carpio koi), Vet Rec vol. 78, 23-28
Hartman K.H., Yanong R. P. E., Pouder D. B., Petty B. D. Francis-Floyd R., and Riggs A. C. (2004). Koi herpesvirus (KHV) disease, Fact sheet VM-149, Extension service, Institute of Food and Agricultural Sciences, University of Florida 2004
Pokorova D., Vesely T., Piackova V., Reschova S., and Hulova J. (2005), Current knowledge on koi herpesvirus (KHV): a review. Veterinary medicine-Czech, vol. 50(4), 139-147
Figure 2: The sources for KHV spreading
A. Infected fish: As long as a fish is infected, no matter if the fish is showing symptoms and if the viruses are small in number, KHV can ruthlessly spread out. KHV was presumed to invade vulnerable fish through gills, because viral DNA is firstly detected in gills in many cases. Yet, Costes et al. proclaimed that KHV is transmitted by a “skin-to-skin” mode when infected fish rubbed other individuals or objects. Uninfected fish can also get infected by pecking skin lesions off or droppings from infected fish.
B. Carriers: Researchers applied various detection methods to support that KHV has a wider range of host besides koi and common carp. Goldfish (Carrassius auratus), Crucian carp (Carassius carassius), grass carp (Ctenopharyngodon idellus), and tench (Tinca tinca), seemed to carry and spread KHV, although all appear not to be affected KHV.
C. Water and mud: KHV remains infectious in water and mud for at least 4 hours and up to three months in a water body according to the report by Minamoto et al. in 2008. Water from the Yura River which had a KHV outbreak in one section was collected for examination. High levels of KHV were still detected after 3 months.
D. Other media: Anything, such as a net or a filter, which had contact with the virus, could possibly transmit the virus.
Bibliography
Costes B., Sta;om Raj V., Michael B., Fournier G., Thirion M., Gillet L., Mast J., Lieffrig F., Bremont M., Vanderplasschen A. (2009), The major portal of entry of koi herpesvirus in Cyprinus carpio. Journal of Virology, vol. 83 no. 7, 2819-2830
El-Matbouli M., Saleh M., and Soliman H. (2007), Detection of cyprinid herpesviurs type 3 in goldfish cohabiting with CyHV-3-infected koi carp (Cyprinus carpio koi), Vet Rec vol. 78, 23-28
Hartman K.H., Yanong R. P. E., Pouder D. B., Petty B. D. Francis-Floyd R., and Riggs A. C. (2004). Koi herpesvirus (KHV) disease, Fact sheet VM-149, Extension service, Institute of Food and Agricultural Sciences, University of Florida 2004
Pokorova D., Vesely T., Piackova V., Reschova S., and Hulova J. (2005), Current knowledge on koi herpesvirus (KHV): a review. Veterinary medicine-Czech, vol. 50(4), 139-147
Friday, March 12, 2010
What is KHV?
KHV (Koi herpesvirus) is a highly contagious viral disease which was first reported in 1998, after the outbreak in Israel. However, analysis of archived materials indicated that a koi farm in the United Kingdom was infected by KHV in 1996. Since then,
KHV has been found in most countries that cultivate common carp and/or koi. The world organization for animal health (OIE) has listed KHV as a serious reportable disease since 2006.
The koi herpesvirus only attacks koi and common carp. That means the virus has no impact on other fish species, or on humans who eat the infected fish. The reason that this disease scares hobbyists and aquaculture farmers is that KHV often causes more than 80% to nearly 100% mortality in both fries and adult carp.
Some researchers recognized this unknown virus had similar shape and characters as other herpes viruses. Based on morphology and the sequential development in the host cell nucleus, the new virus was designated as koi herpesvirus. On the other hand, based on the finding of exceptional large size of dsDNA and distinct DNA sequences in KHV, it was once called as “carp interstitial nephritis and gill necrosis virus” (abbreviated as CNGV) by Ilouze et al. to reflect its clinic symptoms shown in infected fish. The dispute on designation was subsided when Waltzek et al. found the most convincing evidence to group KHV within the Herpesvirus family in 2005. KHV genome encodes several genes closely related to homology in two known cyprinid herpsviruses, namely carp pox virus (Cyprinid herpesvirus-1, CyHV-1) and hematopoietic necrosis herpesvirus (CyHV-2). Together with previous morphological and biological description, KHV officially became the third member (CyHV-3) of Cyprinid herpesviruses.
Bibliography”
Aoki T., Hirono I., Kurokawa K., Fukuda H., Nahary R., Eldar A., Davison A. J., Waltzek T. B., Bercovier H., and Hedrick R. P. (2007), Genome sequence of three koi herpesvirus isolates representing the expanding distribution of an emerging disease threatening koi and common carp worldwide. Journal of Virology, vol. 81(10), 5258-5065
Gray W. L., Mullis L., LaPatra S. E., Groff J. M., and Goodwin A. (2002), Detection of koi herpesvirus DNA in tissues of infected fish. Journal of Fish Diseases, vol. 25, 171-178
Hartman K.H., Yanong R. P. E., Pouder D. B., Petty B. D. Francis-Floyd R., and Riggs A. C. (2004). Koi herpesvirus (KHV) disease, Fact sheet VM-149, Extension service, Institute of Food and Agricultural Sciences, University of Florida 2004
Hedrick R. P., Marty G. D., Nordhausen R.W., Kebus M. J., Bercovier H., Eldar A. (2000), An herpesvirus associated with mass mortality of juvenile and adult koi Cyprinus carpio. Fish, Health Newsletter, Fish Health Section, American Fisheries Society, vol.12 (1), 44-57
Ilouze M., Dishon A., and Kotler M. (2006), Characterization of a novel virus causing a lethal disease in carp and koi. Microbiology and Molecular Biology Review, vol.70(1), 147-156
Kalupahana A.W., and De Silva D. P. N.(2009), Application of polymerase chain reaction (PCR) technique to detect koi herpes virus (KHV) infection in carps. Proceedings of the Peradeniya University Research Session, vol. 14, 68-72
Ornamental Aquatic Trade Association (OATA). 2001. http:\\www.ornamentalfish.org
Pokorova D., Vesely T., Piackova V., Reschova S., and Hulova J. (2005), Current knowledge on koi herpesvirus (KHV): a review. Veterinary medicine-Czech, vol. 50(4), 139-147
Waltzek T. B., Kelley G. O., Stone D. M., Way K., Hanson L., Fukuda H., Hirono I., Aoki T., Davison A. J., and Hedrick R. P. (2005). Koi herpesvirus represents a third cyprinid herpesvirus (CyHV-3) in the family Herpeviridae. Journal of General Virology, vol. 86, 1659–1667
KHV has been found in most countries that cultivate common carp and/or koi. The world organization for animal health (OIE) has listed KHV as a serious reportable disease since 2006.
The koi herpesvirus only attacks koi and common carp. That means the virus has no impact on other fish species, or on humans who eat the infected fish. The reason that this disease scares hobbyists and aquaculture farmers is that KHV often causes more than 80% to nearly 100% mortality in both fries and adult carp.
Some researchers recognized this unknown virus had similar shape and characters as other herpes viruses. Based on morphology and the sequential development in the host cell nucleus, the new virus was designated as koi herpesvirus. On the other hand, based on the finding of exceptional large size of dsDNA and distinct DNA sequences in KHV, it was once called as “carp interstitial nephritis and gill necrosis virus” (abbreviated as CNGV) by Ilouze et al. to reflect its clinic symptoms shown in infected fish. The dispute on designation was subsided when Waltzek et al. found the most convincing evidence to group KHV within the Herpesvirus family in 2005. KHV genome encodes several genes closely related to homology in two known cyprinid herpsviruses, namely carp pox virus (Cyprinid herpesvirus-1, CyHV-1) and hematopoietic necrosis herpesvirus (CyHV-2). Together with previous morphological and biological description, KHV officially became the third member (CyHV-3) of Cyprinid herpesviruses.
Bibliography”
Aoki T., Hirono I., Kurokawa K., Fukuda H., Nahary R., Eldar A., Davison A. J., Waltzek T. B., Bercovier H., and Hedrick R. P. (2007), Genome sequence of three koi herpesvirus isolates representing the expanding distribution of an emerging disease threatening koi and common carp worldwide. Journal of Virology, vol. 81(10), 5258-5065
Gray W. L., Mullis L., LaPatra S. E., Groff J. M., and Goodwin A. (2002), Detection of koi herpesvirus DNA in tissues of infected fish. Journal of Fish Diseases, vol. 25, 171-178
Hartman K.H., Yanong R. P. E., Pouder D. B., Petty B. D. Francis-Floyd R., and Riggs A. C. (2004). Koi herpesvirus (KHV) disease, Fact sheet VM-149, Extension service, Institute of Food and Agricultural Sciences, University of Florida 2004
Hedrick R. P., Marty G. D., Nordhausen R.W., Kebus M. J., Bercovier H., Eldar A. (2000), An herpesvirus associated with mass mortality of juvenile and adult koi Cyprinus carpio. Fish, Health Newsletter, Fish Health Section, American Fisheries Society, vol.12 (1), 44-57
Ilouze M., Dishon A., and Kotler M. (2006), Characterization of a novel virus causing a lethal disease in carp and koi. Microbiology and Molecular Biology Review, vol.70(1), 147-156
Kalupahana A.W., and De Silva D. P. N.(2009), Application of polymerase chain reaction (PCR) technique to detect koi herpes virus (KHV) infection in carps. Proceedings of the Peradeniya University Research Session, vol. 14, 68-72
Ornamental Aquatic Trade Association (OATA). 2001. http:\\www.ornamentalfish.org
Pokorova D., Vesely T., Piackova V., Reschova S., and Hulova J. (2005), Current knowledge on koi herpesvirus (KHV): a review. Veterinary medicine-Czech, vol. 50(4), 139-147
Waltzek T. B., Kelley G. O., Stone D. M., Way K., Hanson L., Fukuda H., Hirono I., Aoki T., Davison A. J., and Hedrick R. P. (2005). Koi herpesvirus represents a third cyprinid herpesvirus (CyHV-3) in the family Herpeviridae. Journal of General Virology, vol. 86, 1659–1667
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