Pathogenesis of HIV and its implications for serodiagnosis and monitoring of antiviral therapy

Human immunodeficiency virus (HIV) is lymphotropic and neurotropic. In vivo clinical and immunological abnormalities develop in a large proportion of long-term HIV antibody seropositive persons. Different stages of HIV infection are marked by expression of HIV genes, production of HIV antibodies, formation of antigen/antibody complexes and clearance of such complexes. Transient HIV antigenemia appearing generally 6-8 wk prior to HIV antibody (HIV-Ab) seroconversion and lasting 3-4 mth is generally seen in acute infection. IgM antibodies predominantly to core proteins may occasionally be detectable when, or just before, IgG antibodies appear. If IgG antibodies to both envelope and core proteins persist in the absence of HIV-Ag the short-term prognosis is relatively good. However, HIV-Ag seroconversion may appear at any time after HIV-Ab seroconversion. Progression to AIDS is strongly associated with declining or absent levels of IgG antibodies to p24. IgG2 and IgG4 antibodies to HIV, which are mainly directed to p24, disappear most dramatically. Titers of antibodies to HIV p24 below 64 are strongly associated with the presence of HIV antigen and a poor clinical outcome. HIV antigen was detected frequently in sera from children in all stages of infection in contrast to adults whose sera were generally HIV-Ag negative when asymptomatic and positive when AIDS was apparent. HIV antigen may be less efficiently detected with the present assays in sera from regions where the prototype strains of HIV (HTLV-III and LAV) are less prevalent, like Central Africa. Persistence of HIV-Ag in cerebrospinal fluid (CSF) appears to be pathognomonic for progressive encephalopathy, particularly in children. Levels of HIV-Ag in serum, and possibly in CSF, can be decreased by nucleoside analogues, such as AZT. This indicates HIV-Ag and possibly antibody to HIV core protein p24 as suitable markers for selecting individuals for antiviral therapy as well as monitoring the efficacy of such therapy.

Viral gene expression, antibody production and immune complex formation in human immunodeficiency virus infection

Human immunodeficiency virus (HIV) antigen (HIV-Ag) in polyethylene glycol (PEG) precipitates and supernatants and HIV antibodies (HIV-Ab) to core and envelope antigens were studied in serial serum samples of three HIV-Ab seroconverters and 11 HIV-Ab seropositive men with a mean follow-up time of 16.1 months. In five men not progressing beyond persistent generalized lymphadenopathy (PGL) and two progressing to AIDS, HIV-Ag was detected once in 'free' configuration before HIV-Ab seroconversion and persistently or intermittently 'complexed' thereafter; in six of these men HIV core antibodies were continuously present with a declining level in one. In two men not progressing beyond PGL and five progressing to AIDS HIV-Ag was detected 'complexed' before HIV-Ab seroconversion once and persisted predominantly in 'free' configuration thereafter, while no HIV core antibody was detected in six of these men and a declining level in one. HIV-Ag was detected in 37% (14 out of 38) of HIV core antibody seropositive samples, mostly in 'complexed' form, while HIV-Ag was detected in 86% (43 out of 50) of HIV core antibody seronegative samples, mostly in both 'complexed' and 'free' configuration. Antibodies to HIV envelope antigen were detected in all HIV-Ab seropositive samples. These results indicate that the level of HIV-Ag expression is the primary determinant of detectability of HIV core antigens as well as antibodies. Enhancement of HIV-Ag expression, in a significant number of cases associated with clinical deterioration, appears to lead to clearance of HIV core antibodies in immune complexes, while HIV envelope antibody levels remain relatively unaffected.

Persistent HIV antigenaemia and decline of HIV core antibodies associated with transition to AIDS

Sequential serum samples from 13 homosexual men who seroconverted for antibodies to human immunodeficiency virus (HIV) were tested for HIV antigen. In one of these men, who developed the acquired immune deficiency syndrome (AIDS), HIV antigenaemia preceded the onset of AIDS by more than a year and persisted throughout the course of the disease. This antigenaemia was accompanied by the disappearance of IgG antibody reactivity to the major HIV core protein p24. In none of the 12 others, who all remained without serious disease, were serum concentrations of HIV antigen detected, except on one occasion in one man. All their serum samples showed strong IgG antibody reactivity to p24. Nine children who were infected with HIV in 1981 by plasma transfusion from a single donor were also followed up for HIV antigenaemia. HIV antigen was almost constantly present in the serum (26 of 28 samples) of five children who developed AIDS related complex or AIDS and less often in the serum (four of 10 samples) of four children who remained free of symptoms. The two children who developed AIDS showed a virtual absence of antibody reactivity to p24. These results indicate that increased HIV gene expression is a contributing factor to the development of AIDS and also provide evidence for a switch from latent to active HIV infection.

High-K diets reduce brain haemorrhage and infarcts, death rate and mesenteric arteriolar hypertrophy in stroke-prone spontaneously hypertensive rats

Male stroke-prone spontaneously hypertensive rats (SHRSP) were fed 4% NaCl diets containing either 0.75% normal K or 2.11% high K, starting at 6 weeks of age. After 8 months on these diets 69% of 58 SHRSP rats on 0.75% K had died, whereas 2% of 95 rats of 2.11% K died, a 98% reduction in mortality, P less than 0.000 001. After 20 weeks the daytime and night-time blood pressure (BP) of each rat were measured intra-arterially. We selected two groups precisely matched for BP. One matched SHRSP group (BP 182 mmHg) ate the 0.75% K diet and 30 of 47 rats died (64% mortality). The other matched SHRSP group (BP 182 mmHg) ate the 2.11% K diet, and two of 35 died (6% mortality, a 91% reduction of mortality, P less than 0.0001). Seemingly, the striking reduction in mortality rate with the 2.11% hig-K diet does not depend on a lowering of BP. High-K diets do not change body Na or K. The dry weight of mesenteric arterioles was reduced by 22% on 2.11% K diet versus 75% K (7.5 versus 9.7 mg) (P less than 0.001), indicating a greatly reduced hypertensive hypertrophy. In nine surviving SHRSP on 0.75% K, 13 of 36 brain hemisphere slides (four slides per rat) showed infarcts (36%). In 11 surviving SHRSP on 2.11% K, one of 44 brain slides showed infarcts (2%, a 94.5% reduction, P less than 0.0001). Brain haemorrhage was reduced by 92% on the 2.11% K diet. High-K diets allow cerebral arteries to carry very high BPs without sustaining damage to the artery wall, thereby drastically reducing brain infarcts and lowering the death rate.

Expression of human immunodeficiency virus antigen (HIV-Ag) in serum and cerebrospinal fluid during acute and chronic infection

Human immunodeficiency virus antigen (HIV-Ag) was detected in the serum of most adult (13/16) and paediatric (6/6) AIDS patients and rarely in the serum of symptomless seropositive controls (1/13). It was present in the cerebrospinal fluid (CSF) of all 5 children and most (5/9) adults with AIDS-related encephalopathy, but not in the CSF of 13 symptomless seropositive controls, of whom 8 had antibody in the CSF. A longitudinal study of 1 of the controls with antibody in the CSF showed that HIV-Ag in CSF was present transiently before the occurrence of antibody in the CSF. In serial samples of serum from 35 men who seroconverted HIV-Ag was detected in 11 persons--in 5 before seroconversion and in 6 after. 3 of the 6 who became antigenaemic after seroconversion remained so for the rest of the follow-up. AIDS was diagnosed in 1 patient, 3 months after HIV-Ag was first detected in serum and 6 months after seroconversion. The findings suggest that HIV-Ag appears early and transiently in primary HIV infection. Antibody production follows, after which HIV-Ag may disappear. Its persistence or reappearance seems to correlate with clinical, immunological, and neurological deterioration.

Implantation of cultured thymic fragments in patients with acquired immunodeficiency syndrome

Cultured thymic fragments were implanted in one patient with acquired immunodeficiency syndrome (AIDS)-related complex (ARC) and in eight AIDS patients with opportunistic infections (OIs, four patients), Kaposi's sarcoma (KS, two patients), or both (two patients). Thereafter, objective clinical improvement was noted in one patient with OI, and a stable symptom-free condition was observed in the ARC patient and in two other patients with OIs. However, the ARC patient and two of the three patients with OIs developed infections three to six months after implantation. A fourth case of OI and the patients with KS showed progression of the disease. Peripheral blood investigations for counts of total leukocytes, lymphocytes, and T-lymphocyte subsets as well as for lymphocyte stimulation with mitogens showed no changes interpretable as an improvement of the cellular immune deficiency status. We conclude that cultured thymic fragments have no distinct in vivo effect on the course of AIDS, except for a temporary clinical improvement or a period of stable condition in some patients with OIs.

Cultured human thymus epithelial monolayer cells induce CD4 expression on mononuclear cells of AIDS patients in vitro

We investigated the in vitro effect of cultured human thymic epithelial monolayer cells on mononuclear cells (MNC) from patients with Acquired Immune Deficiency Syndrome (AIDS) and AIDS-related complex (ARC). Patients having undergone bone-marrow transplantation (BMT), who showed a similar deficiency of T-lymphocytes expressing CD4 (Leu-3, T4), and healthy blood donors served as controls. Most epithelial monolayer cells were of thymic medulla origin, as documented using a panel of monoclonal antibodies to thymic epithelial cells. In AIDS/ARC patients the CD4-positive cells (ranging between 4 and 30% of MNC) increased by a factor of 1.56 (s.e.m. 0.15, n = 12) during a 2 h incubation on the monolayer. Human fetal lung fibroblasts were inactive in this respect. There was no consistent change in cells expressing CD3 (Leu-4, T3), CD5 (Leu-1) or CD8 (Leu-2, T8). In BMT patients and healthy controls, neither thymus epithelium nor fibroblasts had any effect on T cell marker expression. Incorporation of tritiated thymidine by stimulated or unstimulated lymphocytes was increased after incubation for 3 days on either epithelium or fibroblasts. We conclude that CD4 expression is induced on MNC from AIDS/ARC patients during a 2 h incubation on epithelial monolayers.

Gallium-67 lung scintigraphy in patients with acquired immune deficiency syndrome (AIDS)

Fifteen 67Ga lung scans were obtained from 11 men with AIDS to detect opportunistic lung infection. Results were compared with clinical findings, chest radiographs, CO-transfer and transbronchial biopsies or BAL. Clinical symptoms were least helpful in diagnosing pneumonia. Chest radiographs were normal in six of eight normal 67Ga studies and abnormal in four of seven abnormal scans. In four cases the X-ray showed equivocal abnormalities, twice corresponding to a normal and twice to an abnormal scan. Once the X-ray was normal, but the scan showed diffuse abnormalities. CO-transfer in patients with a normal scan was higher (55-68%) than in patients with an abnormal scan (22-44%). Biopsy or BAL revealed P. carinii in five of six patients. Cytomegalo-virus was isolated once. All six patients had abnormal 67Ga scans. 67Ga lung scintigraphy is a sensitive indicator of active lung disease in AIDS, especially when chest X-rays are normal or equivocal.

Distinct IgG recognition patterns during progression of subclinical and clinical infection with lymphadenopathy associated virus/human T lymphotropic virus

Longitudinal IgG recognition patterns of viral proteins were studied in 15 men who had seroconverted for lymphadenopathy associated virus/human T lymphotropic virus (LAV/HTLV-III). Antibodies to the major viral core protein p24, which is a cleavage product of the gag gene encoded precursor protein pr55, appeared first. These were soon followed by antibodies to pr55 and more gradually by antibodies to the other gag gene encoded cleavage product p18, the env gene encoded transmembrane glycoprotein gp41, the env gene encoded glycoproteins gp65 and gp110, and the putative pol gene product p33. In 13 subjects who remained healthy the reactivity to the different proteins increased or stabilised with time, while in two men who developed acquired immune deficiency syndrome (AIDS) the reactivity, most noticeably to gag encoded proteins, diminished before or at the onset of symptoms.

Potassium prevents death from strokes in hypertensive rats without lowering blood pressure

Adding potassium to normal chow reduces death rate in hypertensive stroke-prone (SHRSP) rats from 83 to 2%, a 98% reduction. An 86% reduction in deaths occurred even when blood pressure (BP) was virtually equal in the two SHRSP groups being compared. Potassium supplements in the diet also reduced stroke deaths in hypertensive Dahl S rats from 55 to 4%, a 93% reduction. There was an 87% reduction in deaths even when BP was actually equal in the two Dahl S groups being compared. The added potassium in the diets decreased BP moderately in SHRSP rats and modestly in Dahl S rats, which contributed somewhat to the reduction in strokes. However, more importantly, the added potassium seems to reduce the intrinsic susceptibility to cerebral artery lesions for a given level of hypertension, even when BP is not lowered.