Reference no: EM1398305

A project is underway to develop a vaccine against mouse hepatitis virus, a pathogen of mice. The vaccine consists of capsid protein of the virus, which is injected subcutaneously as a depot in alum on day 0. At days 5 and 14, the group of six mice is bled and the serum is tested for the presence of antibodies against the viral capsid protein. Separate assays are done for each of the immunoglobulin classes, IgM, IgG and IgA. The amounts, expressed in ?g/ml of antibody, are shown in the figure below. When the data is analysed it appears that two of the animals (asterisks) have high titres of antibody particularly IgG and IgA, at both days 5 and 14. a) Why do the titres of IgG antibodies increase more rapidly between days 5 and 14 than do IgM antibodies, in all animals? b) Propose an explanation for the high titres of IgG antibodies in the two animals indicated at day 5. Can this explanation also account for the relatively high levels of IgA antibodies also seen in these mice? (Note: Mouse hepatitis virus infections can be common in animal houses) The spleens from mice taken at day 14 are used to produce B cell hybridomas making monoclonal antibodies against the viral protein. Of the clones produced, 15 produced IgG, three produce IgM and none produced IgA. c) Why do you suppose there are no IgA-producing clones, despite the good IgA response ? d) You want a high-affinity antibody for use in an assay. Which of the clones you have produced are likely to be of higher affinity? e) Describe how monoclonal antibodies are produced.