Two co-habitation studies with common carp were conducted to determine whether latent infections of koi herpesvirus (KHV) exist. Fish were exposed to KHV using 2 different temperature profiles, which induced low and high initial mortality. Subsequently, certain groups of fish were co-habited with naïve fish while others were not. Koi herpesvirus was reactivated in fish from 3 of the 5 experimental tanks. Reactivation of the virus occurred regardless of the initial mortality associated with the virus or whether fish were co-habited with naïve fish. The reactivation of the virus in our experiments occurred several months after the initial exposure to KHV and appeared to be temperature dependent. KEY WORDS: Koi herpesvirus · KHV · Latent infections · Reactivation · Common carp · Co-habitation Resale or republication not permitted without written consent of the publisherDis Aquat Org 67: [15][16][17][18][19][20][21][22][23] 2005 virus can infect fish and remain in an inactive state until conditions are more favourable.Exposure of carp to KHV at non-permissive temperatures (less than 17°C or greater than 28°C) has been used in the Koi carp industry to induce immunity to the virus (Ronen et al. 2003). Data suggest that at the high end of the non-permissive temperature range, exposed fish develop specific immunity, which upon rechallenge, affords protection. However, there is much debate as to whether this strategy of inducing a 'natural immunity' produces latent infections in fish (Walster 2003), and whether these fish can subsequently transmit the virus to naïve fish.The objectives of this study were to determine whether KHV can persist in common carp after initial virus exposure, and whether the virus can be transmitted to naïve fish by co-habitation. MATERIALS AND METHODSVirus isolate. The UK D-132 Koi herpesvirus isolate (CEFAS) was used to challenge fish in both exposure experiments in this study. The virus was propagated on a koi fin cell line (Hedrick et al. 2000).Fish maintenance. Fig. 1 provides a schematic diagram of the experimental tanks used in this study. All tanks, unless otherwise stated, were on a flow-through system utilizing approximately 2 l min -1 of de-chlorinated bore-hole water. Fish were fed a maintenance diet of 1% bodyweight d -1 throughout the experiment. Fish were monitored for mortalities 2 times d -1 during the course of the study.KHV Exposure 1. Fish: One thousand common carp were purchased from a private farm with no history of KHV. The fish ranged from juveniles (aged ~1 yr), weighing between 25 and 30 g, to older fish that weighed between 150 and 200 g. One hundred fish were placed in each of two 300 l tanks (Tanks 1A and 2A) and served as controls. The 800 remaining fish were placed in a 900 l tank (Tank 1B). Prior to starting the study, fish were brought up to a temperature of 21°C from 10°C (1°C d -1 for 11 d). Ten fish were euthanized prior to exposure to KHV and blood was collected from the caudal vein. Serum was tested for KHV-specific antibodies using an ELISA (se...

We conclude that we should be screening for the risk factors associated with low BMD in adults with ID. If these are present further investigations should take place and those found to have osteoporosis and osteopenia should have treatment at an early stage to prevent morbidity and improve their quality of life.

Genetic relationships between 35 spring viremia of carp virus (SVCV) genogroup Ia isolates were determined based on the nucleotide sequences of the phosphoprotein (P) gene and glycoprotein (G) genes. Phylogenetic analysis based on P gene sequences revealed 2 distinct subgroups within SVCV genogroup Ia, designated SVCV Iai and Iaii, and suggests at least 2 independent

Common carp, Cyprinus carpio L., exposed to koi herpesvirus (KHV) may become persistently infected and populations containing such virus-infected individuals may transmit the virus to other fish when co-habited. Detection of virus-infected fish in a population is thus critical to surveillance and control programmes for KHV. A study was therefore designed to detect anti-KHV serum antibodies, with an enzyme-linked immunosorbent assay, in common carp following experimental exposures to KHV under varying environmental conditions. The study determined that a proportion of fish within a population experimentally exposed to KHV (at least 10-25%) develop high antibody titres (1/1600 or greater) to the virus, and this immunological response was detectable for several months (observed at the termination of the experiments at 65, 46 and 27 weeks post-exposure). Furthermore, this response was detected in one population of fish that did not succumb to a high level of mortality when maintained at water temperatures that were non-permissive for KHV. Elevating the water temperatures to permissive conditions for KHV resulted in recurrence of disease despite the presence of anti-virus antibodies, suggesting that serum antibodies alone are not protective under the conditions of our trials.

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