CONCENTRATION OF FISH ENVELOPED VIRUSES FROM LARGE VOLUMES OF WATER

The validity of several concentration procedures for the detection of fish enveloped viruses present in large volumes of water was determine d. Viral haemorrhagic septicaemia virus (VHSV) was used to evaluate ad sorption/elution to positively-charged MK filter cartridges for the co ncentration of enveloped viruses. For fresh water, the efficiency of t he procedure ranged from 12 to 100%, with a mean recovery of 57%. In s eawater samples, the recoveries varied from 15 to 100%, with a mean re covery of 59%. The same virus was used in methods such as organic floc culation and ammonium sulphate flocculation with very poor recoveries of infectious virus, caused by the inactivation of VHSV in both proced ures. Concentration of seawater samples from tanks housing sea bass or gilthead affected by viral erythrocytic infection and lymphocystis, r espectively, were carried out. In both cases, the viruses responsible for the outbreaks were detected by electron microscopy in the concentr ated water samples.