Comparison of cell culture-grown JC virus (primary human fetal glial cells and the JCI cell line) and recombinant JCV VP1 as antigen for the detection of anti-JCV antibody by haemagglutination inhibition

Abstract

JC virus (JCV) is the causative agent of the demyelinating disease progressive multifocal leucoencephalopathy (PML), which can be diagnosed by detection in the cerebrospinal fluid (CSF) of both JCV DNA and intrathecally-produced anti-JCV antibody. However, the restricted in-vitro species and cell tropism shown by JCV has made antigen production difficult and limited serological investigations both in PML diagnosis and for JCV epidemiology. In this study antigen prepared as a crude cell lysate of JCV-infected primary human fetal glial (PHFG) cells was compared in a haemagglutination inhibition (HI) assay with antigen produced from the JCV carrier cell line, JCI, and yeast-expressed JCV VP1. Forty-two sera were tested with each antigen and there was a high level of correlation between the assays: 96.5% between the HI assays with PHFG and JCI antigens and 98.1% between the HI assays with PHFG and recombinant VP1 (rVP1) antigens. The JCI antigen gave HI titres 19% lower than the PHFG antigen ( P=0.022). Titres with the rVP1 antigen were 2% higher than with the PHFG antigen ( P=0.83). When serum/CSF pairs from 11 PML patients were tested, the antibody index calculated in each case confirmed the production of intrathecal anti-JCV antibody. Antibody testing for JCV is no longer reliant on PHFG cells and JCV serological tests should be available more widely.