Experiment Table CD4+ T lymphocyte counts and viral RNA Results Tetramer Staining Results Neutralizing Antibody Assays Results Viral Sequencing Results Peptide-binding Assays Results ELISPOT assays Results Conclusion   Navigation Home Methods Results Conclusion Quiz Links       click for Quiz

Neutralizing Antibody Assays Results     This graph shows Antibody production rose as is expected following an initial infection. They maintained high levels as CD4 counts fell and viral replication increased.   What are antibodies? Which cells in the immune system produce them? Answer Antibodies are small Y shaped proteins that bind to antigens and direct immune processes They are produced by B-cells   The high antibody titre is likely due to constant exposure to the viral antigens. As replication of the virus increases so does exposure and activation of B-cells (antibody generating cells) and more antibodies specific for HIV are produced. This data demonstrates that the subject is experiencing constant exposure to HIV and that an antibody response is unable to contain the infection.  Now let's compare this graph with results from an earlier experiment... Interesting...We know that the cell mediated response is failing due to massive cell killing by the SHIV virus.If the immune system was failing why are the antibody concentrations are rising? Perhaps the B-cells of the immune system remain functional even with breakdown of the T-cell populaton. But if this interpretation is correct why is the virus still thriving?   If antibodies were effective at neutralizing the virus, why might enough still escape to maintain a population? Answer The HIV genome is integrated in the chromosomes of infected host cells, as well as constant mutations by the virus allowing it to escape detection What is the danger would a population of SHIV still pose against the body even after being reduced to a small amount? Would HIV posess the same threat? Answer Even in small amounts  SHIV is capable of mutating in ways that allow it to escape recognition. HIV is similar in its abilities. The experimenters were vague when explaining changing antibody levels in the subject choosing instead to focus on the cell mediated side of the story. Nevertheless, whatever action the antibodies may have for antigens it did contact it is clear that the humoral response did not play as significant a role in clearly out HIV as the cell response. In light of this fact, would you see any evolutionary advantage for the HIV-like viruses to target the cell mediated arm? Answer Yes, by directly targeting the cells the virus is increasing its numbers and improving its fitness NEXT