Early Indus Valley Civilization ... their Geograhpy, their customs and Indo-Aryan civilization with the earliest caste system.
Antibodies contribute to immunity in three main ways: they can prevent pathogens from entering or damaging cells by binding to them; they can stimulate removal of a pathogen by macrophages and other cells by coating the pathogen; and they can trigger direct pathogen destruction by stimulating other immune responses such as the complement pathway.
By definition, antibodies bind to specific antigens. In the case of an antibody which fights viruses, the antigen is a specific viral protein. Antibodies bind the HA, the important receptor-binding protein of the influenza virus, blocking it so it can't infect other cells.y definition, antibodies bind to specific antigens. In the case of an antibody which fights viruses, the antigen is a specific viral protein. Antibodies bind the HA, the important receptor-binding protein of the influenza virus, blocking it so it can't infect other cells.