FTIR spectroscopic method for detection of cells infected with herpes viruses

Microscopic FTIR spectroscopy was used to investigate the spectral differences between normal cells in culture and cells infected with various members of the herpes family of viruses [Herpes simplex (HSV) and Varicella zoster (VZV)]. The main objective of this study is to evaluate the possibility of developing microscopic FTIR spectroscopy as a sensitive assay for the detection of herpetic infections at their early stages. The advantage of this method over conventional FTIR spectroscopy is that it facilitates inspection of restricted regions of tissue. Our results showed significant and consistent differences between all normal and HSV or VZV infected cells that were tested. Detectable and significant spectral differences between normal and infected cells are seen as early as 24 h postinfection, but the damage of the cells (cytopathic effect), caused by the infecting virus, can be seen by optical microscope observations at only 3 days postinfection. An impressive increase in the levels of vital cellular metabolites was seen in the herpes virus infected cells compared to normal cells. It seems that this spectral behavior is unique for infection with herpes viruses, because when these cells were infected with other viruses from different families like retroviruses, a considerable decrease in the levels of vital cellular metabolites was seen in infected cells compared to normal cells. Cluster analysis performed on FTIR mass chromatography yielded 100% accuracy in classifying control uninfected and VZV or HSV infected cells. Our data strongly support the possibility of developing FTIR microscopy as a diagnostic method for early detection of herpetic infections.