Identifying infections with respiratory syncytial virus using specific IgG and IgA ELISAs on oral-fluid samples

Centre for Geographic Medicine Research – Coast, Kenya Medical Research Institute/Wellcome Trust Research Programme, Kilifi, Kenya; Centre for Infections, Health Protection Agency, London, UK; Department of Biological Sciences, University of Warwick, Coventry, UK

^* To whom correspondence should be addressed. Email: eokiro{at}nairobi.kemri-wellcome.org.

	Abstract

Currently, identification of respiratory syncytial virus (RSV) infection in epidemiological studies is by virus antigen or nucleic acid detection in combination with serology. Oral-fluid specimens may provide a non-invasive alternative to blood more suitable for sampling outside of the clinic setting. We evaluated an indirect enzyme-linked immunosorbent assay (ELISA) for the detection of RSV specific immunoglobulins (Ig) G and A using oral-fluid samples collected from individuals with immunofluorescent antibody test (IFAT) confirmed RSV infections. In five children sampled repeatedly from birth, antibody profiles in oral fluid quite consistently tracked those in paired sera and detected RSV infections with rising antibody titres of at least one Ig class. Specific IgG responses were generally more reliable than IgA, except in early infancy, where the reverse was sometimes true. In a further five young children in whom oral fluid was collected weekly following RSV infection, boosted antibody responses were observed, frequently of a transient nature lasting a few weeks; specific IgG responses were of longer duration and more pronounced than specific IgA. Our data show significant promise for the use of oral fluid alone in RSV infection surveillance. The observed rapid dynamics of the antibody responses are informative in defining study sampling intervals.