Infection of a poikilothermic cell line (XL-2) with eastern equine encephalitis and western equine encephalitis viruses.

This research investigates the sensitivity of Xenopus laevis cell line (XL-2) to Eastern and Western Equine Encephalitis viruses, comparing it to primary chick embryo cell cultures, traditionally used for virus isolation and assay. Both cell cultures infected with the viruses experienced similar effects, demonstrating that XL-2 could be a potential alternative for virus studies.

Objective of the Study

• The study aimed to assess the sensitivity of a continuous cell line (XL-2) originating from the toad, Xenopus laevis, as opposed to routinely used primary chick embryo cell cultures (CEC), for the isolation and assay of Eastern Equine Encephalitis (EEE) and Western Equine Encephalitis (WEE) viruses. These two viruses are both known to cause diseases in humans.

Methodology

• Both XL-2 and CEC cell systems were infected with EEE and WEE viruses. These viruses were isolated from the brain of a horse and a sick pigeon, respectively.
• The team observed for any cytopathic effect (CPE), changes indicating that a cell has been infected with a virus.

Findings

• The study revealed that a clear cytopathic effect (CPE) was observed in both infected cell cultures, characterized by rounding and detachment of cells. This destruction was partial by 18 hours post-infection and total by 24 hours.
• There were no significant differences between the infectious titres of EEE and WEE viruses in the XL-2 cells and the CEC. This insinuates that the toad cell line might also be sensitive to these viruses.
• Both viruses produced small plaques in XL-2 cells within the diameter range of 0.5-1.0 mm.
• Presently, studies are being conducted to explore the sensitivity of the XL-2 cells for direct isolation of the two viruses from field samples, and for the detection of Cuban flaviviruses via the immunofluorescence test.

Implications

• If the XL-2 cell line continues to show promise in these studies, it could provide an alternative to primary chick embryo cell cultures for the isolation and assay of viruses, including EEE and WEE. This could have significant implications for virology.