ABSTRACT

The aim of this work was to determine the tenacity of tortoise viruses under natural conditions. Three viruses isolated from Hermann's tortoises, Testudo hermanni, or spur-thighed tortoises, Testudo graeca, were used as test agents: a chelonian herpesvirus, isolate 4295/7R/95, an iridovirus, isolate CH8/96, and a picomavirus-like virus “x”, isolate TGT1A/96. Each virus was adsorbed onto an electropositively charged membrane filter which was sandwiched between two polycarbonate membranes with pores. The sandwiched membranes were stored in drinking water and lake water at 4°C (39°F), room temperature (between 20 and 27°C (68 and 81°F) and 37°C (99°F) in the laboratory, and in soil outside in the early spring and in the summer. The remaining virus was eluted after defined intervals and quantified by virus titration.

The reduction of infectious virus was very small over weeks at 4°C (39°F) in drinking and lake water. Three log10 units of virus were inactivated in about one to eight weeks at room temperature (between 20 and 27°C (68 and 81°F). At 37°C (99°F) this inactivation rate was reached in three days to six weeks. No large differences were noticed between drinking and lake water. In soil the viruses were more stable outside during the spring than the summer. Within nine to twenty-four weeks a reduction of three log10 units was detected in the spring, whereas this inactivation rate was calculated within two to three weeks during the summer. The herpesvirus is more sensitive to the tested conditions than the iridovirus and virus “x.”