Acquired immunodeficiency disease virus

Viruses are small infectious agents composed of a nucleic acid genome (DNA or RNA) encased by structural proteins and in some cases a lipid envelope. They are the causative agents of a number of human infectious diseases, the most important for public health today being acquired immunodeficiency syndrome (AIDS), hepatitis, influenza, measles, and vituses causing diarrhoea (e.g., rotavirus). In addition, certain viruses contribute to the development of cancer. Antiviral drugs inhibit viral replication by specifically targeting viral enzymes or functions and are used to treat specific virus-associated diseases. 

M ore than 200 viruses have been identified as capable of producing disease Acute viruses, such as the common cold, have a rapid onset and quick recovery. Chronic viral infections, such as acquired immunodeficiency syndrome (AIDS), have recurrent episodes of exacerbations (increases in severity of symptoms of the disease) and remissions (periods of partial or complete disappearance of the signs and symptoms). Display 14-1 describes the viruses discussed in this chapter. 

We have discussed in a general way the nature of animal viruses in the first part of this chapter. Now we discuss in some detail the structure and molecular biology of a number of important animal viruses. Viruses will be discussed which illustrate different ways of replicating, and both RNA and DNA viruses will be covered. One group of animal viruses, those called the retroviruses, have both an RNA and a DNA phase of replication. Retroviruses are especially interesting not only because of their unusual mode of replication, but because retroviruses cause such important diseases as certain cancers and acquired immunodeficiency syndrome (AIDS). 

The human immunodeficiency virus began to spread among the homosexual population in the United States in the late 1970s, but it was not until 1981 that physicians in New York and at the Centers for Disease Control in Atlanta recognized the new clinical syndrome (acquired immunodeficiency syndrome), alerting the world to a new and fatal infection. 

There is no good animal model for infection by HIV. The virus will infect several primates, but it does not produce active disease and it is not practical to use primates for propagation of the virus. The chimpanzee has been used in vaccine trials to determine whether neutralizing antibody is produced and whether the growth of the virus can be inhibited in vivo. More productive work has been done using the immunodeficiency viruses of the species (e.g., simian immunodeficiency virus in macaques, feline immunodeficiency virus in cats) to study pathogenesis and treatment of retroviral acquired immunodeficiencies. 

The human immunodeficiency virus (HIV) causes the immunodeficiency disease known as AIDS (acquired immune deficiency syndrome). The structure of this virus is similar to that of the influenza virus (A). 

The human immunodeficiency virus (HIV) is one of only a few retroviruses known to infect humans. It is estimated that approximately twenty-two million people are now infected worldwide [1]. With only a tiny number of exceptions, infection ultimately leads to the development of the lethal condition of acquired immunodeficiency syndrome, or AIDS. To date, only a handful of drugs have been shown to have any effect on the course of the disease. These are, in general, relatively ineffective at significantly prolonging life, and drug resistance develops rapidly. Equally discouraging, vaccines have not yet been developed to prevent infection. 

Acquired immunodeficiency syndrome (AIDS), a degenerative disease of the immune and central nervous systems, is responsible for a rapidly growing fatality rate in the world population. Although no cure has been found, research worldwide is aimed at developing strategies for chemotherapy. The causative agent is the human immunodeficiency virus... 

Secondary immunodeficiencies (9) are much more common than primary ones and frequently occur as a result of immaturity of the immune system in premature infants, immunosuppressive therapy, or suigery and trauma. Illnesses, particularly when prolonged and serious, have been associated with secondary immunodeficiencies, some of which may be reversible. Acquired immune deficiency syndrome (AIDS) (10—12) may be considered a secondary immunodeficiency disease caused by the human immunodeficiency viruses HIV-1 or HIV-2. Hitherto unknown, the disease began to spread in the United States during the latter part of the 1970s. The agent responsible for this infection has been isolated and identified as a retrovirus. 

The human immunodeficiency virus (HIV) is the causative agent of acquired immunodeficiency syndrome (AIDS), a disease that has claimed the lives of tens of millions of people since the 1980s. Because of the vast impact of AIDS on global health, HIV and its molecular biology have been intensely studied to determine potential drug targets for intervention. 

Finally, there is an increasing need to evaluate the importance of environmental toxins in the pathology of Alzheimer s disease. There has been much interest lately in the role of aluminium as a causative factor, while the studies of dementia associated with the acquired immunodeficiency syndrome have focused attention on the effects of slow viruses in causing brain cell death. 

In 1997, it was estimated that 30 million adults were infected with the human immunodeficiency virus (HIV) worldwide, with increments of five people infected every minute. It is estimated that approximately 7% of the population of sub-Saharan Africa has been infected. The incubation of the disease is 7 to 8 years. Currently available drugs for acquired immunodeficiency syndrome (AIDS) and HIV are zidovudine, didanosine, lamivudine, and stavudine. The causative agent for AIDS is generally an HIV virus, which is transmitted by sexual contact, blood and blood products, the use of contaminated drug needles, and from mother to fetus. 

At the global level, an analysis of the WHO database on burden of disease (http //www.who.int/evidence) shows that most of these deaths result from a handful of causes (WHO, 2005a). Figure 1 shows the major causes of death in children under five years of age. Estimates from the 2000-2003 database attribute 37% of these deaths to neonatal causes, 19% to pneumonia, 17% to diarrhoea, 20% to other — including injuries, measles, and human immunodeficiency virus (HIV)/acquired immunodeficiency syndrome (AIDS) — and 8% to malaria. 

The World Health Organization (WHO), the United Nations Children s Fund (UNICEF) and many other organizations are involved in the procurement of pharmaceutical products. In particular, the supply of pharmaceutical products used in the treatment of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), malaria and tuberculosis has become a major concern at both the international and country levels. Commitments by the European Commission and G8 countries, among others, offer the potential for significant increases in funding for efforts to combat communicable diseases. Low-cost pharmaceutical products of assured quality have the greatest potential for maximizing the impact of these efforts. The need for a model quality assurance system... 

Coates RA, Farewell VT, Raboud J, Read SE, MacFadden DK, Calzavara LM, Johnson JK, Shepherd FA, Fanning MM (1990) Cofactors of progression to acquired immunodeficiency syndrome in a cohort of male sexual contacts of men with human immunodeficiency virus disease. Am J Epidemiol 132 717-722... 

HIV/AIDS human immunodeficiency virus/acquired immunodeficiency syndrome HUI Health Utilities Index HYEs healthy-year equivalents ICC intraclass correlation coefficient KDQOL Kidney Disease Quality of Life instrument MCS mental component summary scale of the SF-36 MOS-HTV Medical Outcomes Study HIV Health Survey MOT Medical Outcomes Trust MSQOL Migraine Specific Quality of Life NHP Nottingham Health Profile PCS physical component summary scale of the SF-36 QALY quahty-adjusted hfe year QOL quahty of life QOLIE Quality of Life in Epilepsy QWB Quality of WeU-Being scale SF-36 MOS 36-Item Short-Form Health Survey SIP Sickness Impact Profile VAS visual analog scale WY well year YHL years of healthy life... 

STD, sexually transmitted disease HIV, human immunodeficiency virus UTI, urinary tract infection PID, pelvic inflammatory disease HDL, high-density lipoprotein cholesterol BV, bacterial vaginosis AIDS, acquired immunodeficiency syndrome IV, intravenous. 

Centers for Disease Control and Prevention. Guidelines for national human immunodeficiency virus case surveillance, including monitoring for human immunodeficiency virus infection and acquired immunodeficiency syndrome. MMWR 1999 48 1-31. 

Several other international efforts involve consortia. In fact the leading causes of human deaths worldwide are not heart disease, stroke, or cancer, but diseases of malnutrition and infectious pathogens. The top three killers are diseases of famine (e.g., anemia), malaria, tuberculosis, and HIV (human immunodeficiency virus)/AIDS (acquired immunodeficiency syndrome). Malaria is considered as the foremost killer of children, whereas AIDS is considered as the world s foremost killer of adults. Millions of children in Africa die of malaria every year. 

Health and Public Policy Committee, American College of Physicians and the Infectious Diseases Society of America. 1988. The acquired immunodeficiency syndrome (AIDS) and infection with the human immunodeficiency virus (HIV). Annals of Internal Medicine 108 460 169. 

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