Capture-ELISA for serum IgM antibody to respiratory syncytial virus

Class-specific antibodies to bovine respiratory syncytial virus in experimentally infected lambs

Enzyme-linked immunoabsorbent assay (ELISA) was used to titrate virus-specific IgG, IgM and IgA levels in nasal secretions, lung lavage fluids and serum samples sequentially obtained from lambs experimentally infected with bovine respiratory syncytial virus (RSV). Virus-specific IgG and IgM responses were measured by the indirect double antibody sandwich ELISA using anti-bovine RSV monoclonal antibody, as capture antibody, and peroxidase-conjugated anti-sheep IgG and anti-sheep IgM. Virus-specific IgA antibodies were measured by antibody capture assay using anti-sheep IgA (alpha-chain specific) and anti-bovine RSV monoclonal antibodies. Bovine RSV-specific IgM and IgA antibodies were detected in the serum samples within 6 days post-inoculation (p.i.). Virus-specific IgC antibodies appeared in serum samples 4 days later. In nasal secretions, IgA antibodies appeared 7 days p.i. but IgM antibodies were not detected until 12-16 days p.i. In serum samples, IgM titres were predominant for the first 2 weeks p.i. IgC titres becoming predominant thereafter. In nasal secretions and lung lavage fluids, IgA titres were significantly higher than IgM or IgG titres up to 21 days p.i. (0.01).

Monoclonal antibody-based capture enzyme immunoassays for specific serum immunoglobulin G (IgG), IgA, and IgM antibodies to respiratory syncytial virus

Monoclonal antibodies (MAbs) to the fusion protein (F), attachment protein (G), and nucleoprotein (N) of respiratory syncytial (RS) virus were evaluated for use as detector antibodies in immunoglobulin G (IgG), IgA, and IgM capture enzyme immunoassays. MAb assays were tested against assays using polyclonal antibodies (PAbs) with serum specimens from patients with and without evidence of recent RS virus infection. Assays developed with N MAbs were comparable to or better than PAb assays for detecting specific IgG and IgM antibodies but were somewhat less sensitive for IgA. F MAb assays were less sensitive for IgG and IgM antibodies but identified specific IgA in some specimens negative by N MAb assay. G MAb assays were insensitive for IgG and IgM antibodies but did detect about 50% of the IgA antibodies identified by the PAb assay. The basis for the low sensitivity of the G MAb assays is unclear, since many of these specimens were positive for IgG antibodies to G by Western immunoblot. The sensitivity of MAb assays varied with patient age: N MAb assays detected specific antibody responses to RS virus in all immunoglobulin classes in both adults and infants less than 1 year of age, F MAb assays detected specific IgG responses in adults and IgA responses in both adults and infants, and G MAb assays only detected IgA responses in adults. A mixture of N and F MAbs was complementary overall, identifying 54 of 55 (IgG), 51 of 52 (IgA), and 16 of 17 (IgM) serum specimens positive by PAb assay. These MAb assays were also specific with specimens tested from persons without a history of recent RS virus infection. The availability of these MAb-based assays offers other laboratories the opportunity to have long-term, standardized reagents and tests for serological diagnosis of RS virus infection.