Chronic infections from the perspective of evolution: a hypothesis

The prime role of plasma membrane cholesterol in the pathogenesis of immune evasion and clinical manifestations of falciparum malaria

The pathogenesis of falciparum malaria, with its immune evasion, mechanism of immune suppression and immunological inertia, the cause of its preferential incidence in children and pregnant mothers, and the pathological basis of clinical manifestations, are discussed from biochemical, biophysical and immunological perspectives. Sequestration and recrudescence are highlighted as the evolved means by which malaria parasites survive. These discussions are based on a novel hypothesis that changes in the lipid matrix fluidity of plasma membrane, through alterations of cholesterol and phospholipid content and variation in body temperature, significantly affect the membrane functions of cells. The pathogenesis of aggressive behavior in cerebral malaria is postulated to be different from that of coma, and complicated pregnancy in malaria is also discussed as a multifactorial condition wherein hypocholesterolemia, resulting from increased membrane biogenesis of multiplying parasites, is the common underlying factor.

The viral envelope in the evolution of HIV: a hypothetical approach to inducing an effective immune response to the virus

The human immunodeficiency virus (HIV) is 'perceived' by the host immune system as partly-self because of the presence of host cell wall membrane on the viral envelope. This perception leads to an ineffective immune response to the virus. It is proposed that only viral core antigens without the envelope will be perceived as non-self by the host immune system and can provoke an effective immune response. In normal uninfected persons, core antigens could therefore serve as a vaccine. In HIV infected persons, uncommitted immunocytes from the peripheral leucocytes freed from antibodies will in vitro process autologous viral core antigens as non-self antigens and lead to an effective immune response against the HIV when reinjected into the patient. The use of autologous viral core antigens provides, at the same time, a means for testing viral core antigens as possible vaccines without any risk to a third person. This immunotherapy of the HIV, when confirmed, will support core antigens as possible vaccines and could also be applied to the large group of retroviral and other enveloped viruses that cause chronic infections and malignant tumours in man and animals, with considerable benefits to human and animal health.