Koi Herpes Virus: Do Acipenserid Restitution Programs Pose a Threat to Carp Farms in the Disease-Free Zones?

Abstract

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. 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.

Susceptibility of stone loach (Barbatula barbatula) and hybrids between sterlet (Acipenser ruthenus) and beluga (Huso huso) to cyprinid herpesvirus 3

“…The total number of positive fish detected by nested PCR is listed in Table 1. Kempter et al (2009) reported that Atlantic sturgeon and Russian sturgeon are susceptible to CyHV-3; similarly, we found sterbel to be positive for CyHV-3 DNA. The susceptibility of stone loach (previously member of family Cobitidae, now Balitoridae) might suggest that species of the family Cobitidae could be generally susceptible to CyHV 3; for instance, Kempter et al (2012) reported susceptibility of spined loach.…”

Is There Any Species Specificity in Infections with Aquatic Animal Herpesviruses?–The Koi Herpesvirus (KHV): An Alloherpesvirus Model

“…The fact that the disease has never been found within other fish than C. carpio, namely in common carp and koi, did not detract from the ------------1 21 st 29 -32 + -+ -----+ 2 -------28 28 -+ + 3 29 -30 + -+ 31 29 29 + + + 4 31 --+ --30 28 28 + + + 5 28 --+ ------- possibility of virus replication in other fish species and investigations were not conducted to investigate the role of KHVD transmission through vector fish species, i.e., its transfer as an infectious agent to naive carp detected by a combination of virological and serological methods other than in carp or koi [38]. It has since been found that a lot of other fish species such as goldfish, crucian carp, different sturgeon species, grass carp (Ctenopharyngodon idella), silver carp (Hypophthalmichthys molitrix) or tench (Tinca tinca) may be act as a healthy appearing carrier hosts which can transfer the KHV to naive carp or koi [22,24,26,27,39]. KHVD has never occurred in any of those fish species when inoculated with KHV.…”

“…For CyHV-3 or koi herpesvirus (KHV), although KHV disease (KHVD) is induced only in the species C. carpio (common carp and koi), it has been demonstrated that this virus can be present, and sometimes replicated, in a lot different fish species living in fresh and brackish water. KHV DNA has been identified by different PCR methods in a lot of members of the families Acipenseridae [22], Cyprinidae, including common carp or koi hybrids [23][24][25], and Percidae in many wild fish populations within close vicinity to, or in carp ponds [26,27]. Furthermore KHV has also been detected in fresh water mussels and crustaceans [28].…”

Koi Herpes Virus: A Review and Risk Assessment of Indian Aquaculture

“…Hybrids of goldfish and carp or koi are also susceptible to experimental infection of KHV [8,35]. KHV has been detected by PCR in Russian sturgeon and Atlantic sturgeon from fish farms in Northern Poland [44]. Susceptible host range of KHV and its nature of infection in different fish species are shown in Table 2.…”