Canine coronavirus inactivation with physical and chemical agents

Abstract

Canine coronavirus (CCoV) is responsible for mild or moderate enteritis in puppies. The virus is highly contagious and avoiding contact with infected dogs and their excretions is the only way to ensure disease prevention. Since no studies have yet focused on the sensitivity of CCoV to chemical biocides the present investigation examined the efficiency of physical and chemical methods of viral inactivation. CCoV infectivity was stable at +56 degrees C for up to 30 min, but tended to decrease rapidly at +65 degrees C and +75 degrees C. Germicidal ultra-violet (UV-C) light exposure demonstrated no significant effects on virus inactivation for up to 3 days. CCoV was observed to be more stable at pH 6.0-6.5 while extreme acidic conditions inactivated the virus. Two tested aldehydes inactivated the virus but their action was temperature- and time-dependent. The methods for CCoV inactivation could be applied as animal models to study human coronavirus infection, reducing the risk of accidental exposure of researchers to pathogens during routine laboratory procedures.

Fig. 1

Effect of heat treatment on CCoV infectivity in vitro. Virus aliquots were incubated at three different temperatures, +56 °C (a), +65 °C (b) and +75 °C (c), and were removed and titrated by the TCID₅₀ assay at fixed time points. The straight line delineates the detection limit of the test.

Fig. 2

Effect of UV–C radiation on the infectivity of CCoV in vitro. Virus aliquots were placed at a distance of about 4 cm from the UV–C source and were removed and then titrated by the TCID₅₀ assay at fixed time points. The straight line delineates the detection limit of the test.

Fig. 3

Effect of different pH conditions on the infectivity of CCoV in vitro. Virus aliquots were exposed to alkaline and acidic conditions and incubated at different temperatures: +4 °C, +25 °C and +37 °C for 1 h. After reversing to neutral conditions, the samples were titrated by the TCID₅₀ assay.