<Li> neutralization of viruses so that these organisms cannot enter cells, </Li> <Li> or by T lymphocytes, which will kill a cell parasitized by a microorganism . </Li> <P> The immune system response to a microorganism often causes symptoms such as a high fever and inflammation, and has the potential to be more devastating than direct damage caused by a microbe . </P> <P> Resistance to infection (immunity) may be acquired following a disease, by asymptomatic carriage of the pathogen, by harboring an organism with a similar structure (crossreacting), or by vaccination . Knowledge of the protective antigens and specific acquired host immune factors is more complete for primary pathogens than for opportunistic pathogens . There is also the phenomenon of herd immunity which offers a measure of protection to those otherwise vulnerable people when a large enough proportion of the population has acquired immunity from certain infections . </P>

List three major ways that bacteria can cause harm during an infection