Polyomavirus JC longitudinal seroprevalence in a cohort of Italian newborns

BACKGROUND: JC virus (JCV) is a widespread member of the Polyomaviridae family. Serological studies determined that JCV primary infection occurs asymptomatically in 60-100% of the population during childhood, but the age of JCV exposure has not been yet characterized. This study was conducted to defining the kinetic of maternal antibodies against JCV in infants and to dating the viral primary infection. MATERIAL AND METHODS: an home made indirect Enzyme Linked Immunosorbent Assay (ELISA) was employed, using JCV Viral Protein 1–GST fusion protein to test for the presence of IgG to JCV in serum samples taken from 167 newborns and followed up to three years (time points: 1, 2, 3, 4, 6, 9, 12, 24, 36 months). The cut-off point was determined in each assay by the mean OD reading of the negative controls which were added to standard deviation and multiplied three times. RESULTS: JCV IgG were detected in 92.8 %, and in 77.9% of the newborns within the first and the second month of life, respectively (chi quadro test, p<0.05). The prevalence increased during the time, up to 91.4% and 96.3% after 12 and 24 months, respectively. Antibody amount also significantly increased (p<0,001) after 3 months of life (OD:2.3 times the value of the cut-off), up to 36 months (OD: 4.1 times the value of the cut-off). CONCLUSION: Maternal JCV antibodies wane after about 2 months from the birth, as it happens for other viruses such as rubella and varicella. Infants are thus susceptible at very young age for JCV infection, and almost all the children are subjected to the primary infection within the first year of life.