Question

You have joined a research lab that is testing new vaccines for a new strain of the influenza A virus (IAV). The lab's prior studies have shown that when C57BL/6 laboratory mice are given non-pathogenic bacteria that have been engineered to express a 16 amino acid peptide, after about a month the mice produce IgG antibodies that effectively neutralize IAV. Your project is to test serum samples from healthy adult humans who were given these bacteria 6 weeks ago as part of a pilot clinical trial. You find that you can clearly detect IgG antibodies against IAV from about a third of the samples, but cannot detect IAV-specific antibodies from the remainder of the samples. Which of the following is the most likely characteristic shared by individuals who produced a detectable antibody response?

Group of answer choices

They have a genetic polymorphism that causes their T cells to produce comparatively high amounts of IL-2

They express MHC class II allotypes that bind efficiently to the 16 amino acid peptide expressed by the bacteria

They are people who also have pollen allergies

They express a self protein that contains an amino acid sequence identical to the 16 amino acid peptide expressed by the bacteria

They all have genetic polymorphisms in genes for complement proteins that result in inefficient clearance of bacteria by the membrane attack complex (MAC)

Answer 1

• option B is correct , as helper T cells perform a main role in antibody production by activating B cells to produce antibodies. As helper T cells act by MHCII which is exogenous antigen that phagocytes bacteria and fungus which grow in tissue and extracellular fluid ,and present their antigen to helper T cells to produce new MHCII cells that are associated with peptide chain called invariant chain which prevent them from binding with other peptide in the ER and helps in assembly and movement of MHCII to endosomal compartment having antigen derived peptides. then removal of CLIP occurs and antigen derived peptide is loaded to empty site , antigen presented vesicle fuse with cell and get expressed on its surface to phagocyte bacteria. In this way allotypes of MHCII bind efficiently to 16 aminoacid peptide by bacteria
• option A can also be correct as IL2 is produced by T cells which help in lymphocyte proliferation and differentiationso in individual who produce antibody response to bacteria may be due to this production of IL2 by T cells
• option C is incorrect as allergies reduce immune response which does not favour production of antibodies so it cannot act way to eliminate bacteria
• option D is incorrect if similar protein sequence as that of 16 sequence present , it can cause autoreactive cells which cause autoimmune diseases
• option E is incorrect MHC molecules effciently clears the bacteria and the immune response is produced from binding of MHC with the antigens produced y bacteria.