Memory T cells are the key players in protecting against most intracellular bacteria and parasites. Antibody is occasionally though rarely protective. Viruses Viruses are a very diverse group of obligate intracellular pathogens. Almost every form of immunity comes into play against some type of virus. Enveloped viruses can be damaged by complement attack, and some directly bind C1q or homologous collectins.
Phagocytes can take up and destroy antibody and complement coated viruses.
1 cells taken in temporal order in a first encounter. Protection against subsequent challenge varies with the behaviour of the virus but antibody is highly effective in preventing reinfection if it is of the right type and against the appropriate epitope. Antibody which prevents infection of a susceptible host cell by a virus is termed neutralising . This property requires that the antibody either prevent binding of the virus to its' receptor or blocks some reaction necessary for viral entry. Because of the slower response time, T cell memory is rarely able to prevent the establishment of a secondary infection but is of considerable importance in limiting its' spread.