Inverse relationship between HIV-1 p24 antigenemia, anti-p24 antibody and neutralizing antibody response in all stages of HIV-1 infection

A double blind cohort study was conducted on 149 homosexual males and 36 patients with AIDS to investigate the relationship between HIV-1 antigenemia, the presence of neutralizing antibody (NA) activity and specific anti-viral core protein (p24) antibody (Ab) in the sera of HIV infected individuals during their progression to AIDS. All AIDS patients and 68% (101/149) of the homosexual males were HIV seropositive upon entering the study. Of those 48 (32%) homosexuals who were HIV negative at the onset, three seroconverted during the two year observation period. Retrospective studies of the HIV(-) subjects' sequentially stored serum samples demonstrated an early transient appearance of gag encoded p24 antigen (Ag) which preceded their production of NA and specific anti-p24 Ab. Following their seroconversion, no more circulating p24 Ag could be detected. Among the 101 HIV positive homosexuals, 16% rapidly progressed to AIDS and seven of these 16 (44%) subjects eventually died during the two year observation period. In this group of individuals with poor prognosis, presence of NA and anti-p24 Ab commenced at the onset reaching peak levels just prior to developing AIDS and began to decline as the clinical course worsened. Their circulating level of p24 Ag remained undetectable as long as there was quantifiable NA and anti-p24 Ab in their sera. Reappearance of circulatory p24 Ag, on the other hand, was associated with high risk for progression to AIDS.2+hus, while only 11     

HIV-1 IgA specific serum antibodies and disease progression during HIV-1 infection

OBJECTIVE: To evaluate the role of serum human immunodeficiency virus type 1 immunoglobulin A (HIV-1 IgA) antibodies in the progression of HIV-1 infection in relation to viral load and CD4 cell counts. METHODS: Sequential serum specimens were obtained from 218 homosexual men: 123 HIV-1 seropositives, 24 HIV-1 seroconverters, and 71 HIV-1 seronegatives. HIV-1 IgA antibodies were tested blindly by enzyme-linked immunosorbent assay and Western blot. T-lymphocyte subsets were measured by flow cytometry. Viral plasma load was determined by a sensitive branched DNA assay. RESULTS: HIV-1 IgA antibodies with a titer greater than or equal to 50 were detected among 50% of the seroconverters, 27% of the HIV-1-seropositive asymptomatic subjects, 25% of lymphadenopathy, and 23% of HIV-1-related symptomatic subjects. Among patients with the acquired immune deficiency syndrome, the prevalence of virus-specific IgA antibodies (55%) was significantly higher (p < 0.03) as compared with the HIV-1-seropositive asymptomatic subjects, lymphadenopathy and HIV-1-related symptomatic patients, but not versus the seroconverters (p = 0.8). IgA antibodies to HIV-1 gP160 were the most prevalent among all subjects tested. A significant decrease in CD4 cell counts was observed after HIV-1 seroconversion. Viral load was slightly higher among the seroconverters who demonstrated higher (> or =50) HIV-1 IgA levels. CONCLUSIONS: HIV-1 IgA serum antibodies did not predict the progression of the disease. Correlation between HIV-1 IgA antibodies titer, viral load, and CD4 cell counts was not detected.     

Antibody response to human immunodeficiency virus type 1 protease according to risk group and disease stage.

Three groups with different routes of human immunodeficiency virus type 1 (HIV-1) transmission (homosexual men, hemophiliacs, and children) were studied for serum antibodies to a recombinant form of the HIV-1 protease using an enzyme-linked immunoassay. At 1 year after seroconversion, defined as the moment antibodies to HIV-1 proteins were first detected, 56% (34/61) of the homosexual men had antibodies to protease, and 2 years after seroconversion this percentage was 63% (24/38). Within this 2-year period these antibodies were no longer detected in 16% (9/56). A similar pattern was observed in 20 hemophiliacs who seroconverted after exposure to HIV-1-contaminated blood products. We found that 63% (160/255) of homosexual men in Centers for Disease Control stage II or III, 60% (9/15) of patients with acquired immunodeficiency syndrome (AIDS)-related complex, and 36% (14/39) of patients with AIDS had antibodies to protease. In 255 homosexual men in Centers for Disease Control stage II or III, antibodies to protease were significantly more frequently found in samples lacking HIV-1 antigen (P less than 0.001) and possessing antibodies to HIV-1 core proteins (P less than 0.001). Twenty-four persons who developed AIDS were studied longitudinally: 58% (14/24) had antibodies to protease 1 year before developing symptoms; 29% (7/24) showed a decline and 29% (7/24) showed a loss of antibodies to protease at the onset of symptoms. Within a group of 47 HIV-1-infected children, 90% (18/20) with a stable disease course were persistently protease antibody positive, versus 4 of 27 children (15%) with an unstable disease course (P = 0.0001). These data indicate that HIV-1 protease is expressed and antigenic in most HIV-1-infected individuals and that a decline or absence of antibodies to protease is strongly associated with unstable disease in children and AIDS in adults.     

Prevalence of antibodies to herpes simplex virus 2 among homosexual men either positive or negative for human immunodeficiency viruses in Slovakia

We determined the prevalence of antibodies to herpes simplex virus 2 (HSV-2, HSV-2 antibodies) in sera of homosexual men either positive for human immunodeficiency virus 1 (HIV-1, HIV+, a group of 27 sera) or negative for HIV-1 and HIV-2 (HIV-, a group of 52 sera) in Slovakia. Antibodies to HSV-2 glycoprotein G-2 (gG-2, gG-2 antibodies) were determined by a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and immunoblot analysis. We found that 40% of HIV+ and 23% of HIV- homosexual men were positive for the gG-2 antibodies, what is 3.6 and 2.1 times higher incidence, respectively, than that in the control heterosexual population (Bystrická et al., Acta Virol. 42, 319-324, 1998). Identification of individuals infected with genital herpes among HIV+ and HIV- homosexual men should be succeeded by antiviral therapy in order to prevent transmission of HSV-2 and HIV as well in this community.     

Immune response to a major epitope of p24 during infection with human immunodeficiency virus type 1 and implications for diagnosis and prognosis.

A sequential inhibition enzyme-linked immunoassay (SIEIA) using a peroxidase-conjugated monoclonal antibody reacting to the sequence AAEWDRVHP of p24HIV-1 (amino acids 209 to 217 of p55) was developed in order to detect and determine the titer of antibody to this epitope in various populations of human immunodeficiency virus type 1 (HIV-1)-positive patients. There was a good correlation between SIEIA and a commercially available competition assay that uses recombinant p24 protein and polyclonal antibody to HIV-1 antigen, demonstrating the importance of the described epitope. Analysis of sera from French patients showed a decline of antibody to the AAEWDRVHP sequence associated with the progression of AIDS. No decrease was observed with serum samples from African patients. An immune response to the epitope was detected by SIEIA early in the course of seroconversion. Although our SIEIA uses a single p24 epitope, these data are in accordance with previously published studies in which antibodies to the whole p24 were analyzed. Sera reacting to p24 only (indeterminate profiles by Western blot [immunoblot]) did not bind to AAEWDRVHP. This epitope, which is conserved between HIV-1 and HIV-2/simian immunodeficiency virus, appears to be a major antigenic domain of p24. The area containing the sequence AAEWDRVHP and the corresponding monoclonal antibody may serve as a convenient alternative to whole purified p24 and polyclonal antibody in diagnostic and prognostic assays.     

Increases in soluble CD8 antigen in plasma, and CD8+ and CD8+CD38+ cells in human immunodeficiency virus type-1 infection.

Increases in plasma levels of soluble CD8 (SCD8) antigen and expansion of the CD8+ CD38+ lymphocyte compartment were early immunologic alterations frequently observed prior to detection of antibodies against human immunodeficiency virus type 1 (HIV-1) and diminution of CD4+ cells in subjects at risk to develop AIDS. These increases identified in the 49 seronegative homosexual men were manifest in all 164 homosexual subjects and 45 intravenous drug users (IVDU) positive for HIV-1 antibodies (HIV-1+), 19 patients with ARC, and 29 AIDS patients. Augmentation of plasma sCD8 antigen correlated with increases in both CD8+ and CD8+ CD38+ cells in HIV-1(-) homosexual men (r = 0.35, P less than 0.013; r = 0.48, P less than 0.0005; respectively) and the 258 HIV-1+ subjects (r = 0.25, P less than 0.0003; r = 0.33, P less than 0.0001, respectively). In vitro examination of unstimulated peripheral blood lymphocytes from HIV-1+ homosexuals and IVDU confirmed the fivefold higher constitutive levels of cellular release of sCD8 antigen in these subjects compared to heterosexual controls. Inclusion of radiolabeled amino acids during the 3-day culture period in the presence or absence of phytohemagglutinin resulted in negligible levels of radioactivity associated with the sCD8 antigen indicative of a lack of de novo synthesis. Throughout clinical progression to AIDS, sCD8 antigen levels continued to escalate relative to the numbers of CD8+ cells bearing CD38+ antigen. The data confirm the interrelationship between sCD8+ antigen and CD8+ and CD8+ CD38+ cells.     

Functional antibody response to human cytomegalovirus in immunocompetent and HIV-1 infected individuals with antibodies that inhibit virus penetration into cells and intercellular transmission of viral infection.

Antibodies mediating post-attachment virus neutralisation (PN), inhibition of human cytomegalovirus (HCMV)-induced cell fusion in the glioblastoma cell line U373 (IF) and global neutralising activity (NA) were quantified in sera from healthy immunocompetent individuals, asymptomatic HIV-1-infected subjects and AIDS patients to further characterise the neutralising antibody response to HCMV in these population groups and to assess whether HIV-1-infected individuals exhibited an abnormal functional antibody profile. PN and IF antibodies accounted for a minor fraction of the NA activity of sera from all population groups. Sera from HIV-1-infected individuals (particularly AIDS patients) displayed higher levels of PN and IF antibodies than those from the healthy control group; however, the relative contribution of these antibodies to the global serum NA activity appeared to be lower in the former individuals than in immunocompetent controls. Serum antibodies preventing HCMV cell-to-cell spread (IP) were then measured to determine whether a specific deficiency could be detected in the HIV-1-infected group population. Serum IP antibody titres were significantly higher in HIV-1-infected individuals (particularly in AIDS patients) than in controls. The potential implications of the data for explaining the pathogenesis of HCMV infection are discussed.     

Improved detection of HIV p24 antigen in serum after acid pretreatment

HIV-1 p24 antigen was detected in 554 sera (509 from HIV-1 seropositive individuals and 45 sera from seronegative controls) using a conventional method with acid pretreatment of the sample in order to separate the p24 antigen/anti-p24 antibody immune complexes. In asymptomatic individuals there was a substantial increase in antigen detection (48.2 % vs 8.4 %). Similar results were also observed in ARC (59.1 % vs 12.2 %) and AIDS patients (85.7 % vs 37.1 %). It can be concluded that the acid treatment improves the sensitivity of conventional techniques to detect HIV-1 p24 antigen.     

Elevated beta 2-microglobulin and lysozyme levels in patients with acquired immune deficiency syndrome

beta 2-Microglobulin (beta 2-M) levels in sera and urines, and lysozyme levels in sera, were quantitated in healthy heterosexual men and several groups of homosexual males. The mean beta 2-M levels in sera and urines and lysozyme levels in sera of healthy heterosexual and homosexual men were not significantly different. However, beta 2-M levels in patients with lymphadenopathy syndrome and AIDS were elevated. The mean beta 2-M level in sera of 11 patients with the lymphadenopathy syndrome was 4016 +/- 473 micrograms/l (SEM) (P less than 0.001) and 5409 +/- 462 micrograms/l (P less than 0.001) in 27 patients with AIDS. Similarly, beta 2-M levels in the urines of patients with chronic diarrheal syndrome, lymphadenopathy syndrome, and those meeting the CDC surveillance definition of AIDS were also significantly elevated (P less than 0.025). The mean lysozyme levels in the sera of 11 patients with the lymphadenopathy syndrome was 16.58 +/- 0.04 microgram/ml, and in 27 patients with AIDS 15.40 +/- 1.16 microgram/ml, compared to the mean level obtained in normal heterosexual men of 6.67 +/- 0.42 microgram/ml (P less than 0.001). The results of this study suggest that measuring beta 2-M in serum and urine and lysozyme levels in serum might provide additional useful parameters for the evaluation of patients with AIDS and prodromal syndromes.     

Sperm and seminal plasma antibodies in acquired immune deficiency (AIDS) and other associated syndromes

Although HIV has been established as the etiologic agent in AIDS, other contributory cofactors may be responsible for selective clinical manifestations of the syndrome. While the pathogenesis remains unclear, the development of immunologic abnormalities observed in some homosexual males with AIDS and AIDS-related complex may be attributed to repeated exposure to allogeneic sperm and seminal plasma components. Accordingly, antibody levels to semen fractions were measured in sera from 338 individuals (295 AIDS, 36 ARC, 16 randomly selected homosexuals, 29 patients with infectious hepatitis, 12 hemophiliacs, 20 rheumatic disease patients, and 24 healthy heterosexual adults). The methods were (i) passive hemagglutination for antibodies to human seminal plasma (HuSePl), and (ii) indirect immunofluorescence (IF) assay on methanol-fixed human sperm noting staining of acrosomal, equatorial, postnuclear, and tail main-piece regions. HuSePl was positive in 31% AIDS sera, while 39% were positive by IF. ARC sera were 30% positive for HuSePl and 38% positive IF. No control sera were positive. Results reveal a significant incidence of antibody to sperm and seminal plasma components in ARC and AIDS patients. Because of the known immunomodulating properties of both, it is possible that these responses may indicate risk factors for disease progression and severity.     

Dynamics of the antibody response and p24 antigenemia in HIV-1 infected individuals in Czechoslovakia

In a group of 83 anti HIV-1 positive subjects the antibody response against different structural viral proteins was investigated concurrently with assessment of p 24 antigenaemia. Disappearance of antibodies against the capsidal antigen p 24 was recorded in 12% of 42 patients with ARC and AIDS. On the other hand, these antibodies persisted in all 41 asymptomatic infections throughout the three-year investigation period. Disappearance of antibodies against p 17 antigen was proved in 41% of the patients and in 22 subjects without clinical symptoms. The authors found a rising trend of antigenaemia p 24 in the course of HIV infection. The free p 24 antigen was detected in 62% patients with AIDS and only in 10% asymptomatic infections. The investigation confirmed the importance of investigations of the antibody response and p 24 antigenaemia in the prognosis of development of HIV infection and in monitoring of the effect of therapy.     

An ELISA-inhibition assay for antibody to human immunodeficiency virus core antigen (p24)

An ELISA-inhibition assay based on commercially available HIV-1 p24 antigen tests was developed for detecting p24 antibodies. The test is specific and simple. p24 antibody was detectable in all p24 antigen negative Western blot positive sera, but was detectable infrequently in antigen positive sera. Sera from patients with indeterminate HIV-1 reactions (individuals without evidence of HIV-1 infection who nevertheless had p24 antibody) were p24 antigen negative and p24 antibody negative in the ELISA-inhibition reaction.     

The affinity of IgG antibodies to gag p24 and p17 in HIV-1-infected patients correlates with disease progression.

The affinity of anti-gag antibody was studied for up to 9 years (1984-1993) in sera from 15 HIV-1+ patients with haemophilia. On the basis of their 1993 clinical status patients were divided into two groups: (i) patients who remained asymptomatic (n = 9); and (ii) those who progressed to AIDS between late 1987 and 1993. The affinity constants of antibody for p24 and p17 were determined by a double isotope fluid-phase radioimmunoassay; and the relationships between antibody affinity and titre, patient clinical course, CD4 cell counts and p24 antigenaemia were analysed. The affinity of p24- and p17-specific antibody was up to 100 times greater in asymptomatic patients than in patients who progressed to AIDS. Patients who developed AIDS either lost or failed to develop high-affinity antibodies early in the infection. Asymptomatic patients maintained high-affinity antibodies for several years; however, in some of these patients the affinity of anti-p24 and p17 antibodies subsequently fell later in the study period. The presence of low-affinity antibody and progressive reduction in the titre of specific antibody were earlier predictors of disease onset than CD4 cell counts. The failure to either develop or maintain high affinity gag-specific antibody suggests an early impairment of T helper function in individuals who progressed to AIDS. The presence of antibody of high affinity could be essential in controlling virus replication and the onset of AIDS.     

Induction of antibody to asialo GM1 by spermatozoa and its occurrence in the sera of homosexual men with the acquired immune deficiency syndrome (AIDS).

Compared to healthy homosexual and heterosexual men, homosexual men with acquired immune deficiency syndrome (AIDS) possessed significantly higher levels of IgG antibody to the neutral glycolipid asialo GM1 (ganglio-N-tetraosylceramide) (P less than 0.01). Of 31 homosexuals with AIDS, 36% possessed levels of this antibody that were at least two standard deviations above the mean of the healthy men. Furthermore, asialo GM1 antibody could be removed from serum by adsorption with spermatozoa. Weekly rectal insemination of male rabbits with rabbit semen also led to the appearance of antibody to asialo GM1 by 15 weeks. These results suggest that asialo GM1 is a component of ejaculated spermatozoa and demonstrate that rectal insemination by itself can lead to the production of antibodies to this glycolipid in the rabbit. In addition, asialo GM1 antibodies may be of value as a serological marker for the early detection of individuals with AIDS.     

Seroepidemiology of HTLV-III (LAV) in the Federal Republic of Germany

Summary In 1984 10,281 sera were collected in the FRG and examined for antibodies to HTLV-III (LAV) with an enzyme-linked immunosorbent assay and confirmative tests. Of the German AIDS patients 81% have antibodies. Individuals belonging to AIDS risk groups, homosexuals, haemophiliacs and i.v. drug abusers, have antibody frequencies between 25%–72%. The detection of HTLV-III antibodies in blood donours indicates that the virus is being transmitted by blood transfusions.Abbreviations AIDS acquired immunodeficiency syndrome - LAS lymphadenopathy syndrome - ARC AIDS related complex - LAV lymphadenopathy associated virus - HTLV-III human T-lymphotropic virus type III - HBV hepatitis B virus     

Early Defect of Phagocytic Cell Function in Subjects at Risk for Acquired Immunodeficiency Syndrome

We studied the functions of peripheral blood monocytes and polymorphonuclear cells in 15 apparently healthy homosexual men, eight homosexual or bisexual subjects with unexplained generalized lymphadenopathies (pre-AIDS), four homosexual men with acquired immunodeficiency syndrome (AIDS), and 15 heterosexual men. In comparison with normal controls, the homosexual groups studied presented a decreased monocyte candidacidal activity for Candida pseudotropicalis that gradually deteriorates as the clinical symptoms progress towards AIDS. The monocyte phagocytic function was retained. Although the phagocytic and candidacidal activities of the polymorphonuclear cells did not differ from those of the normal controls, the candidacidal activity in some of the cases studied was unusually enhanced, indicating that the cells were in an activated state. In addition, only two of nine sera tested from asymptomatic homosexual males were positive for antibodies to HTLV-III/LAV, while six out of eight pre-AIDS and both of the two AIDS patients tested had antibodies to AIDS-associated retrovirus. We suggest that in AIDS the phagocytic system is already involved, together with B and T lymphocyte abnormalities, during the early events of the syndrome, even without the detection of AIDS-associated retrovirus antibodies.     

Patterns of antibody reactivity to selected human immunodeficiency virus type 1 (HIV-1) gp160 epitopes in infected individuals grouped according to CD4+ cell levels

We examined sera from 160 HIV-infected individuals for antibodies reactive to HIV-1 gp160 epitopes defined by seven synthetic peptides. Seropositive individuals were placed into three groups based upon levels of circulating CD4+ cells. These groups consisted of individuals with (1) more than 400 CD4+ cells, (2) 200–400 CD4+ cells, and (3) fewer than 200 CD4+ cells/mm³. The percentage of sera containing antibodies reactive with two immunodominant gp160 epitopes (a.a. 304–321 and 600–611) was unchanged between groups, regardless of CD4 cell numbers. The percentage of sera containing antibodies reactive with weakly immunogenic gp160 epitopes, such as those defined by peptides 425–448 and 846–860, declined in the groups as CD4 values decreased. Our results suggest that the patterns of antibody reactivity to gp160 epitopes change as CD4 levels decline. A narrowing of the humoral immune response to epitopes on the envelope of HIV-1 appears to occur with disease progression.     

High titer HIV-1 V3-specific antibodies with broad reactivity but low neutralizing potency in acute infection and following vaccination

Identifying the earliest neutralizing antibody specificities that are elicited following infection or vaccination by HIV-1 is an important objective of current HIV/AIDS vaccine research. We have shown previously that transplantation of HIV-1 V3 epitopes into an HIV-2 envelope (Env) scaffold provides a sensitive and specific means to detect and quantify HIV-1 V3 epitope specific neutralizing antibodies (Nabs) in human sera. Here, we employ this HIV-2/HIV-1 V3 scaffolding strategy to study the kinetics of development and breadth of V3-specific Nabs in longitudinal sera from individuals acutely infected with clade C or clade B HIV-1 and in human subjects immunized with clade B HIV-1 immunogens. HIV-2/HIV-1 chimeras containing V3 sequences matched to virus type (HIV-2 or HIV-1), subtype (clade B or C), or strain (autologous or heterologous) were used as test reagents. We found that by 3-8 weeks post infection, 12 of 14 clade C subjects had a median IC₅₀ V3-specific Nab titer of 1:700 against chimeric viruses containing a heterologous clade C V3. By 5 months post-infection, all 14 subjects were positive for V3-specific Nabs with median titers of 1:8000 against heterologous clade C V3 and 1:1300 against clade B V3. Two acutely infected clade B patients developed heterologous clade B V3-specific Nabs at titers of 1:300 and 1:1800 by 13 weeks of infection and 1:5000 and 1:11000 by 7 months of infection. Titers were not different against chimeras containing autologous clade B V3 sequences. Each of 10 uninfected normal human volunteers who were immunized with clade B HIV-1 Env immunogens, but none of five sham immunized control subjects, developed V3-specific Nabs titers as high as 1:3000 (median 1:1300; range 1:700-1:3000). None of the HIV-1 infected or vaccinated subjects had antibodies that neutralized primary HIV-1 virus strains. These results indicate that high-titer, broadly reactive V3-specific antibodies are among the first to be elicited during acute and early HIV-1 infection and following vaccination but these antibodies lack neutralizing potency against primary HIV-1 viruses, which effectively shield V3 from antibody binding to the functional Env trimer.     

Cytomegalovirus IgG and IgA serum antibodies in a study of HIV infection and HIV related diseases in homosexual men.

The significance of serum IgG and IgA antibodies to cytomegalovirus (CMV) at various stages of human immune deficiency virus (HIV) infection was studied in 175 homosexual men. Sera were obtained from 123 HIV seropositives [41 asymptomatic, 29 with lymphadenopathy associated syndrome (LAS), 22 with AIDS related complex (ARC), and 31 AIDS patients], 17 HIV seroconverters, and 35 HIV asymptomatic seronegatives. The sera were tested blindly for CMV IgA and IgG antibodies using the immunoperoxidase assay (IPA) and CMV infected human embryo cells. Cross-sectional analysis of CMV IgG antibodies at a titer of greater than or equal to 20 showed 87% and 100% prevalence in the HIV seronegative groups and in the HIV seropositive groups, respectively (P less than 0.05). CMV IgG antibodies at a titer of greater than or equal to 80 were present in significantly higher proportions among the HIV seropositive subjects of the various groups as compared with the HIV seronegative homosexual men. However, in the HIV seronegatives who later seroconverted to HIV, a significantly higher prevalence of CMV antibodies (35%) was detected before HIV seroconversion, as compared with the persistently HIV seronegative subjects (14.3%) (P less than 0.05). The HIV seronegatives pre-HIV seroconversion also exhibited a significantly higher geometric mean titer (GMT) of CMV IgG antibodies (62.17 +/- 0.64) as compared with the persistently HIV seronegatives (34.0 +/- 0.6) (P = 0.03). Significantly higher GMTs of CMV IgG antibodies were detected in all the HIV seropositive groups as compared with the persistently HIV seronegative group. CMV IgG antibodies were not detected in the HIV seronegative subjects.(ABSTRACT TRUNCATED AT 250 WORDS)