[Estimate of the validity of a new method for the isolation of rabies virus]

No population-based studies have been conducted to show the potential for the use of virological diagnosis of the rabies virus. The objective of the present study was to estimate accuracy parameters for the isolation of the rabies virus in McCoy cells as an alternative method and to compare this with the use of murine neuroblastoma (N2A) cells, which is considered to be a reference method.

An evaluation was performed on 120 bats collected at random in the Atlantic Forest of the State of São Paulo. The immunofluorescence reaction was utilized for the detection of the rabies virus isolated from the brain of these bats and the presence of the virus was tested in the two cell culture systems. Two data sets were constructed with the results and the analysis was performed using the computer methods for diagnosis tests (CMDT) software by means of the two-graph receiver operating characteristic (TG-ROC) technique to determine sensitivity and specificity parameters, as well as other indicators such as efficacy, positive predictive value, negative predictive value and likelihood ratio.

N2A cells presented 90% sensitivity and specificity, while McCoy cells presented 95% sensitivity and specificity. These values were based on cut-off points optimized for each cell type.

The study showed that McCoy cells allowed the obtaining of accuracy estimates that were better than for N2A. The McCoy cell method is therefore an effective method for the isolation of the rabies virus.