Question

3. Explain the following statement "Immune system co-evolves with pathogens". 4. Provide an argument in favor and against the use of primates as a model system to study the immune system. Justify your answer with the use of appropriate example

Answer 1

(3)

Host–pathogen coevolution, the result of reciprocal selection between interacting hosts and pathogens, is a pervasive and rapid evolutionary force. This antagonistic coevolution has been implicated in the maintenance of sexual reproduction, evolution of diversity, changing population dynamics, and the evolution of pathogen virulence. Coevolution of the host and pathogen, driven by conflicting interests, is akin to an evolutionary arms race. It is in the host’s interest to detect and stop the progression of an infection early by mounting a timely inflammatory response; conversely, it is important for the pathogen to subvert the innate immune system, i.e., the first defense response of the host to establish an infection. The pathogen must also prevent an excessive inflammatory reaction not only to avoid elimination, but also to ensure its own survival by keeping the host alive. To this end, pathogens have evolved strategies to disrupt host immune signaling cascades that culminate in drastic transcriptional upregulation of several pro-inflammatory and other immune response genes.

i) The coevolution of viruses with their hosts and vectors depends on the evolution of the hosts and vectors coupled with factors involved in virus evolution.

ii) Coevolution of Plasmodium species and their vertebrate hosts has left significant signals of selection on the host genome, well-known examples being the hemoglobin structural variants of Homo sapiens (such as sickle-cell anemia, the thalassemias, and G6PD deficiency), which provide a measure of protection against malaria.

iii) Predator–prey co-evolution is the process by which evolution of increased defensive ability in prey causes increased selective pressure for exploitative ability in predators and vice versa.

iv) Coevolution and adaptation between viruses and their hosts are often portrayed as a biological arms race. Viruses are equipped with an array of mechanisms to counteract host defenses that are poised to recognize nonself and activate antiviral pathways, which in turn have driven the development of mechanisms that restrict infection in host organisms across all domains of life.

(2)

Use of primates as a model system to study the immune system will help to understand the disease biology in a much better way.

As the primate biological system is similar to humans. It is always useful to have biologically, functionally systems to study the immune resposes in healthy as well as in diseased condition