Thermal and temporal stability on the enteric viruses infectivity in surface freshwater

The present study aimed to evaluate the stability of Human Adenovirus type 2 (HAdV2) and Murine Norovirus 1 (MNV-1) in surface freshwater samples stored at different temperatures. For HAdV2 the stability decreased with increasing temperatures (-80 > -20 > 4 > 22 degrees C). The time required to reach one log reduction in viral titers (T-90) was similar among all the times and temperatures by different cell-culture based methods and reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The HAdV2 stability decreased with the time of storage temperature and methods employed, aside from samples stored at 22 and 4 degrees C which showed the lowest T-90 values (50 days). For MNV-1, the samples stored at 22 and -20 degrees C showed higher log(10) decay values, followed by 4 and -80 degrees C; while genome persistence was ranked as -80 > -20 > 4 > 22 degrees C. The T-90 values were lower for samples stored at 22 degrees C (33 days), followed by 4, -20 and -80 degrees C with 111, 100 and 333 days, respectively. The results indicate that, under laboratory storage conditions, freshwater samples should be kept at 4 degrees C and at -80 degrees C for short- and long-term periods, respectively. This study provided useful information about thermal and temporal stability of the enteric viruses regarding sample storage conditions.