Temperature inactivation of Feline calicivirus vaccine strain FCV F-9 in comparison with human noroviruses using an RNA exposure assay and reverse transcribed quantitative real-time polymerase chain reaction—A novel method for predicting virus infectivity

• Published in: Journal of virological methods Vol. 156; no. 1-2; pp. 89 - 95
• Main Authors: Topping, J.R., Schnerr, H., Haines, J., Scott, M., Carter, M.J., Willcocks, M.M., Bellamy, K., Brown, D.W., Gray, J.J., Gallimore, C.I., Knight, A.I.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 01.03.2009; Elsevier
• Subjects: Animals; Biological and medical sciences; Calicivirus; Calicivirus, Feline - growth & development; Calicivirus, Feline - pathogenicity; Capsid - drug effects; Cats; Feline calicivirus; Fundamental and applied biological sciences. Psychology; Hot Temperature; Humans; Inactivation; Microbiology; Models, Biological; Norovirus; Norovirus - growth & development; Norovirus - pathogenicity; NoVs; Predictive Value of Tests; Reverse Transcriptase Polymerase Chain Reaction - methods; Ribonucleases - pharmacology; RNA, Viral - analysis; RNA, Viral - drug effects; RNA, Viral - isolation & purification; RNase; RT-QPCR; Techniques used in virology; Viral Plaque Assay; Virology; Virus Inactivation; Virus infectivity; Virus infectivity; Calicivirus; Norovirus; NoVs; Inactivation; RNase; RT-QPCR; Human; Temperature; Microbiology; Vaccine strain; Feline calicivirus; Method; Real time; Virus; Polymerase chain reaction; Caliciviridae; Infectivity; New species; Quantitative analysis
• ISSN: 0166-0934; 1879-0984
• DOI: 10.1016/j.jviromet.2008.10.024

A one-step reverse transcription quantitative real-time polymerase chain reaction (RT-QPCR) method in combination with RNase treatment and low copy number samples was developed in order to examine the effect of temperature on the ability of virus capsids to protect their RNA content. The method was applied to a non-cultivable virus (GII.4 norovirus) and Feline calicivirus vaccine strain F-9 (FCV) which is often used as a norovirus surrogate. Results demonstrated that FCV RNA is exposed maximally after 2min at 63.3°C and this correlated with a greater than 4.5log reduction in infectivity as assessed by plaque assay. In contrast human GII.4 norovirus RNA present in diluted clinical specimens was not exposed maximally until 76.6°C, at least 13.3°C greater than that for FCV. These data suggest that norovirus possesses greater thermostability than this commonly used surrogate. Further, these studies indicate that current food processing regimes for pasteurisation are insufficient to achieve inactivation of GII.4 NoVs. The method provides a novel molecular method for predicting virus infectivity.