Metabolic effects of infection on protein and energy status.

A review of some of the seminal studies of metabolism during various infections indicates that similar patterns of metabolic alterations occur during these illnesses. This patterned metabolic array occurs whether the infection is caused by a gram-positive or a gram-negative bacterium, a rickettsia or a virus, or is respiratory or systemic. In all instances, the previously healthy host responds to infection with cytokine-mediated alterations that appear to occur in proportion to the infectious challenge and to the likelihood of death. These alterations also can occur in the vaccinated host, if the infectious challenge is sufficiently great. Because of their widespread occurrence and seemingly ingrained status, these metabolic alterations may be presumed to be of survival benefit to the host. Whether this patterned array of metabolic sequelae is of benefit to the host, or even to the species, its widespread and systematic occurrence allows it to be of value in assessing the safety and efficacy of vaccines and drugs to prevent or treat a wide variety of infections. In this era of bioterrorism, wherein drugs and vaccines may have to be approved for human use without clinical trials and solely on the basis of animal data, these cytokine-mediated metabolic sequelae can aid in the rational selection of drug and vaccine candidates.