F. X. Abad

Detection of fastidious infectious enteric viruses in water.

A procedure based on the infection of CaCo-2 cells and molecular hybridization with specific cDNA probes has been developed forthe detection of infectious fastidious enteric viruses in environmental samples. CaCo-2 cells, derived from a human colon adenocarcinoma, showed an increased sensitivity when compared to the usual routine host cell line to laboratory strains of rotavirus 3, reovirus 3, astrovirus 1, poliovirus 1, coxsackievirus A 24, enterovirus 70, and adenovirus 5, 40, and 41. Using this methodology, wild-type rotaviruses, enteric adenoviruses, enteroviruses, and for the first time, astroviruses have been detected in freshwater samples. Direct dot-blot hybridization alone was not sufficient for virus detection from environmental samples. CaCo-2 cells may be used as a universal in vivo amplification system for human enteric viruses, enabling the specific monitoring of infectious viral agents in the environment.

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 determined. Viral haemorrhagic septicaemia virus (VHSV) was used to evaluate adsorption/elution to positively-charged MK filter cartridges for the concentration of enveloped viruses. For fresh water, the efficiency of the procedure ranged from 12 to 100%, with a mean recovery of 57%. In seawater samples, the recoveries varied from 15 to 100%, with a mean recovery of 59%. The same virus was used in methods such as organic flocculation and ammonium sulphate flocculation with very poor recoveries of infectious virus, caused by the inactivation of VHSV in both procedures. Concentration of seawater samples from tanks housing sea bass or gilthead affected by viral erythrocytic infection and lymphocystis, respectively, were carried out. In both cases, the viruses responsible for the outbreaks were detected by electron microscopy in the concentrated water samples.