ASTROVIRUS SURVIVAL IN DRINKING-WATER

A method based on infection of CaCo-2 cultured cell monolayers (CC) an d reverse transcription-PCR (RT-PCR) was developed for the specific de tection of infectious astrovirus. The procedure was validated by titra ting poliovirus stocks in parallel in CaCo-2 cells by determining the most probable number of cytopathogenic units and by cell culture and s ubsequent RT-PCR (CC-RT-PCR). CC-RT-PCR was then employed to measure t he persistence of astrovirus suspended in dechlorinated tap water. Aft er 60 days, the decay of astrovirus infectivity was 2 log units at 4 /- 1 degrees C and 3.2 log units at 20 +/- 1 degrees C, while after 90 days, the titer reduction was 3.3 and 5 log units at 4 +/- 1 degrees C and 20 +/- 1 degrees C, respectively. Astrovirus decay in the presen ce of free chlorine (FC) was monitored by CC-RT-PCR. Residual infectiv ity was found after 2 h in the presence of 1 mg of FC/liter. Under the se conditions, astrovirus shows a log titer reduction (LTR) of 4, whil e 0.5 mg of FC/liter induced an LTR of 2.4. The possibility of acquiri ng data on the survival of fastidious viruses in the environment opens new perspectives on the epidemiology of some significant infections t ransmitted by the fecal-oral route.