Abstract
The KHV free carp were experimentally infected with CyHV-3 suspension by immersion at temperatures of 18ºC±1 and 25ºC±1. Skin, brain, gills, liver, spleen, kidneys, and leukocytes were investigated for the presence of KHV DNA, and sera for the presence of antibodies against the virus. Similar investigations were performed with non-infected carp, designed as control groups. The results of KHV DNA detection in the infected carp kept at 25ºC ±1 were compared with the results of the virus isolation onto common carp brain cells using leukocyte co-cultivation method and results of specific antibody detection. The appearance of specific antibodies at various time intervals after detecting the clinical symptoms of KHVD in naturally infected carp was additionally studied. At 18°C water temperature, KHV DNA was not detected up to the 6th d post infection (dpi). Then it was found in samples from skin, gill, liver, spleen, and kidneys and much later from the brain. At 25°C water temperature, KHV DNA was already detected on the 3rd dpi in samples from skin and gills, and from the 5th dpi it was found in all examined internal organs, except the brain where it was found at 6th dpi. At 25°C, isolations of CyHV-3 have succeeded between the 7th and 11th dpi. The first specific antibodies were found no sooner than on the 21st dpi. The serological examination performed in naturally infected carp in 15 carp pond farms showed that first specific antiviral antibodies can be detected 2 weeks after the appearance of clinical symptoms of KHVD.