Question

Q1. An experiment studied the role of the complement system for clearance of bacteria from the blood of mice. Two types of mice were used in the study: C1q-knockout mice and wild type mice. The mice were infected with either antibody-coated or un-coated bacteria (in a fully factorial design, i.e, both mouse genotypes were exposed to both types of bacteria), and the clearance rate was measured during two hours after bacterial administration. Explain the protecting mechanisms (not only those involving complement) at work in mice receiving different treatments.

Q2. An experiment studied the role of the complement system for clearance of bacteria from the blood of mice. Two types of mice were used in the study: C1q-knockout mice and wild type mice. The mice were infected with either antibody-coated or un-coated bacteria (in a fully factorial design, i.e, both mouse genotypes were exposed to both types of bacteria), and the clearance rate was measured during two hours after bacterial administration. Explain the protecting mechanisms (not only those involving complement) at work in mice receiving different treatments.

Q3. Humans have 6 MHC II loci and 3 MHC I loci. Most individuals are heterozygous at all or at least most of these loci. What is the advantage of having many different MHC alleles? Could there also some drawback of having many MHC alleles?

Q4.

You currently have a mild cold, caused by infection by the coronavirus HCoV-OC43, which is quite closely related to the coronavirus currently causing a pandemic in humans, SARS-CoV-2. How do you think the immune response to HCoV-OC43 might affect your susceptibility to infection by the new corona virus, SARS-CoV-2 (where “susceptibility” means both the probability of contracting an infection with SARS-CoV-2, and the severity of the disease symptoms if you actually get infected)? Discuss which aspects of the response induced by HCoV-OC43 that might

• reduce,
• increase, or
• have no effect

on your susceptibility to SARS-CoV-2

Answer 1

Q.3 Answer

MHC bind peptide fragments derived from pathogens and helps for the recognition by T cells. Sometimes polymorphism in MHC affect binding of specific amino acid with MHC molecule.

Q.4 Answer.

During HCoV-OC 44 infection antibodies are produced in human body in response to, these preexisting antibodies may not necessarily be protective against repeated infections of the same virus. If SARS-COV-2 infect a person, susceptible rate will be increased because the immune response shown to HCOV-OC43 will not be useful to SARS -COV-2.