Did you know that koi herpesvirus can infect and cause disease in other species?

I know that most herpesviruses are relatively host-specific, however there are a few exceptions – the simian cercopithecine herpes B virus (which can infect monkeys and humans) and Aujeszky’s disease virus (which affects pigs and a wide range of other animals including cattle, sheep, goats, dogs, cats, mink, foxes, raccoons and rats). Malignant catarrhal fever is another herpesvirus that when it jumps from its natural sheep host to infect cattle, produces severe acute disease that is almost always fatal!

Recent research has demonstrated that although KHV doesn’t cause overt disease in other hosts, it IS capable of infecting them. After mentioning all those other diseases previously, it makes me wonder if under certain circumstances, the KHV may produce disease in other species it is capable of infecting (e.g. viral mutation, immunosuppression, environmental thermal changes, etc). Think about gallid herpesvirus 2 (Marek’s disease virus) picked up an oncogene somewhere along its evolution (M. Bennett, pers. comm).

Dr Sven Bergman and co. in Germany have been working on KHV and recently, they found that not only were carp dying, but it could also infect tench and roach! This information will soon be published and we are privileged to be among the first to know.

The information below are extracts from scientific papers published by Dr Sven Bergman and co. in Germany (provided with permission from the author).

I have forwarded these papers to the lead Australian scientist, Dr Ken McCol, who is planning to inflict this virus on carp and the like, to appeal to his better judgement to abandon his project.

The key sentences to support the prevention of KHV release in Australia are in bold.

How Host Specific is Infection with Koi Herpesvirus (KHV) for Real?
S.M. Bergmann1*, J. Kempter2, D. Fichtner1
1 Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Infectology,
Sudufer 10, 17493 Greifswald-Insel Riems, Germany (* sven.bergmann@fli.bund.de)
2 Agricultural University, Department of Aquaculture, K. Krolewicza 4, 71-550 Szczecin, Poland

Key words: KHV infection, detection methods, nested PCR, non Cyprinus carpio species
Contrary to the theory of host specificity of herpesviral infections, channel catfish herpesvirus
(CCV) is able to infect more than one species, e.g., blue catfish (Ictaluris furcatus), channel catfish
(Ictaluris punctatus), and white catfish (Ictaluris catus). Although African catfish (Clarias
gariepinus), Asian catfish (Clarias batrachus), and other species are resistant to clinical CCV infection,
CCV infected a mammalian cell line obtained from Hawaiian monk seal (Monachus schauinslandi).
Due to these findings, we sought more host species in the framework of koi herpesvirus
(KHV) infection (KHVI). KHV disease (KHVD) occurs only in Cyprinus carpio (common carp and
koi). Among other species, we tested goldfish (Carassius auratus), crucian carp (C. carassius),
tech (Tinca tinca), grass carp (Ctenopharyngodon idella), bighead (Aristichthys nobilis), silver carp
(Hypophthalmichthys molitrix), sheatfish (Silurus glanis), sturgeon species (Acipenser gueldenstaedtii,
A. oxyrhynchus, A. ruthenus), and ornamental fish by different PCRs. All non Cyprinus
carpio fish had never expressed any clinical sign of KHVD. Using different methods for DNA
extraction (clumbs, fluid reagents) from different organs (organs, swabs, smears, blood, etc.), KHV
DNA was detected in most of the experimentally or naturally-infected fish by nested PCR. Positive
PCR results were confirmed by in situ hybridization using different probes, by sequencing of PCR
products, or by immunofluorescence assay using polyclonal and monoclonal antibodies developed
against KHV. In the same framework we tried to establish and test the sensitivity of non-lethal sampling
methods, e.g., separation of leukocytes or gill swabs. Our aim was to exclude or detect KHVI
in fish (carriers) that were in contact with KHV-infected carp or other fish affected by KHVI.

The Israeli Journal of Aquaculture – Bamidgeh 61(3), 2009
Detection of koi herpes virus (KHV) genome in apparently healthy fish.
S. M. Bergmann1*, H. Schütze1, U. Fischer1, D. Fichtner1,

M. Riechardt1, K. Meyer3, D. Schrudde1 and J. Kempter2

1 Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Institute of Infectology,
Südufer 10, 17493 Greifswald-Insel Riems, Germany; 2 Agricultural University, Department of
Aquaculture, K. Królewicza4, 71-550 Szczecin, Poland; 3 Veterinary High school, Hannover, Bünteweg
17, 30559 Hannover, Germany

Abstract
Koi herpesvirus (KHV) induces a lethal disease in species belonging to Cyprinus carpio, covering
common carp and koi or fancy carp. To date, other cyprinid fish species kept together with KHV
infected carp or koi, such as goldfish (Carassius auratus) or grass carp (Ctenopharyngodon idella) had
never shown any sign of KHV infection. Unexplainable outbreaks of KHV infection in common
carp or koi led to the suspicion that more disease influencing factors exist, than so far explained. In
challenge experiments and by natural routes of infection, it has been demonstrated that naive carp
or koi can be infected by the following mechanisms; exposure to water from severe KHV diseased
fish, co-habitation with KHV infected carp, by injection or immersion with cell supernatant of KHV
infected cultures. Experiments were conducted to determine if apparently healthy koi (carriers/
survivors) or non-Cyprinus carpio species stocked with KHV infected carp could become infected.
The study proved that these species were able to transfer KHV to naïve carp. As a result scientists
suspected that some ornamental fish species could act as reservoirs of KHV infection.
In this study goldfish, grass carp, blue back ide (Leuciscus idus) and Ancistrus sp. were screened
with routinely used diagnostic methods such as virus isolation in cell cultures and PCR and found
to be KHV negative. This suggested that these fish species could not be infected by KHV. However,
when using a more sensitive nested PCR, KHV DNA was detected from some of these fish. As
confirmative methods sequence analysis of the nested PCR products and in-situ hybridization with
different KHV probes were used. This study showed that the following cyprinid species; goldfish,
grass carp and ide, and also non-cyprinid species Ancistrus sp. may act as a carrier of KHV.

Bull. Eur. Ass. Fish Pathol., 29(5) 2009, 145

KOI HERPES VIRUS: DO ACIPENSERID RESTITUTION PROGRAMS POSE A THREAT TO CARP FARMS IN THE DISEASE-FREE ZONES?
Jolanta KEMPTER 1*, Jacek SADOWSKI 1, Heike SCHÜTZE 2, Uwe FISCHER 2, Malte
DAUBER 2, Dieter FICHTNER 2, Remigiusz PANICZ 1, and Sven M. BERGMANN 2

1West Pomeranian University of Technology, Division of Aquaculture, Szczecin, Poland
2 Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, Suedufer 10,
17493 Greifswald-Insel Riems, Germany
Kempter J., Sadowski J., Schütze H., Fischer U., Dauber M., Fichtner D., Panicz R., Bergmann S.M. 2009.

Background. Sturgeons have long been extinct in Polish inland waters. A substantial effort has recently been put
into their restitution, covering the drainage areas of two major Polish rivers, the Oder and the Vistula. The
stocked fishes are clinically healthy, but very little is known about their potential to transmit viral diseases including
koi herpes virus (KHV) to healthy fishes of other species, which may pose a threat to the disease-free zones.
This study was intended to determine if sturgeons could be asymptomatic carriers of KHV.
Materials and Methods. A total of 29 sturgeons (two species; length 8–37 cm) originating from fish farms in
northern Poland with a known KHV history in common carp or koi in the area were examined: 15 Russian sturgeons,
Acipenser gueldenstaedtii, with clinical signs of a disease and 14 asymptomatic Atlantic sturgeons,
A. oxyrinchus. The former were sent to the laboratory alive while the latter were sent fixed in ethanol. As it is
required for detection of a latent KHV infection in acipenserids, two independent procedures were applied. The
preliminary results were obtained using PCR. Those findings were subsequently confirmation by nested PCR. The
latter procedure consists of sequence analysis of PCR products and direct detection of KHV infected cells in tissue
materials by in-situ hybridization on nucleic acid level or indirect immunofluorescence on KHV protein level.
Results. KHV genome parts were found in nine Russian sturgeons and four Atlantic sturgeons. Comparison of
PCR results obtained from three primer pairs used for KHV diagnostic in sturgeon showed that those designed
by Bercovier et al. (2005) were most sensitive and robust for this purpose. In order to confirm the presence of
viral particles the most useful method was in-situ hybridization (ISH), allowing the detection of KHV in gill samples
obtained from live sturgeons.
Conclusion. This preliminary study shows that sturgeons can be carriers of KHV. Therefore a viral diagnostics
is highly recommended not only for sturgeons obtained from the environment but also for fertilized eggs, fry, and
fish intended for re-stocking measurements of inland waters.
Keywords: Koi herpesvirus, Acipenser gueldenstaedtii, Russian sturgeon, Acipenser oxyrinchus, Atlantic sturgeon,
PCR, nested PCR, ISH, iIFA

ACTA ICHTHYOLOGICA ET PISCATORIA (2009) 39 (2): 119–126