Low HIV-1 proviral DNA burden detected by negative polymerase chain reaction in seropositive individuals correlates with slower disease progression

Feline immunodeficiency virus diagnosis after vaccination

Prior to the widespread use of vaccination for the control of feline immunodeficiency virus (FIV) infection, diagnosis was made by the detection of antibodies against FIV. A number of commercial animal side tests perform quite well for this determination, with positive predictive values between 91 and 100% and negative predictive values between 96 and 100%. Furthermore, results of these tests could be confirmed by western blot analysis of FIV test-positive sera. Currently, a killed whole virus FIV vaccine has been made available to practitioners. Vaccinated cats seroconvert by ELISA and western blot, making presently available diagnostic tests, which rely on antibody detection, useless in cats after vaccination. The advisory panels of the American Association of Feline Practitioners and Academy of Feline Medicine both recommend testing for feline leukemia virus antigen and FIV antibody before vaccination.

Pilot studies of single and combination antiretroviral therapy in patients with primary biliary cirrhosis

OBJECTIVE

Preliminary reports suggest that patients with primary biliary cirrhosis (PBC) have evidence of human betaretrovirus infection. The aim of this study was to determine whether antiviral therapy impacts on the disease process.

METHODS

We conducted two consecutive open-labeled, nonrandomized, 1-yr pilot studies; the first with lamivudine 150 mg/day and the second with Combivir combination therapy using lamivudine 150 mg and zidovudine 300 mg twice a day. Eleven PBC patients enrolled in each study, seven patients were entered into both studies, and one patient was withdrawn from each study due to side effects.

RESULTS

Evaluation of liver biopsies before and after lamivudine therapy showed a 4-5 increase in necroinflammatory score, a 1-1.5 elevation in bile duct injury, with little change in the percentage of portal tracts with bile ducts (50-52%). None of the patients in the lamivudine study normalized alkaline phosphatase. Histological assessment following Combivir therapy revealed a 6 to 4 improvement in necroinflammatory score (p < 0.03, 95% CI: 0.53-2.33), a 3 to 1 reduction in bile duct injury (p < 0.02, 95% CI: 1.08-2.07), and a 45-75% increase in portal tracts with bile ducts (p < 0.05, 95% CI: 0.02-0.29). In the Combivir cohort, five patients normalized alkaline phosphatase and four developed normal AST, ALT, and alkaline phosphatase.

CONCLUSIONS

Histological and biochemical endpoints were achieved in the Combivir pilot study suggesting a larger placebo-controlled trial is required as a proof of principle to assess whether antiviral therapy impacts the PBC disease process.

Quantification of proviral load of human immunodeficiency virus type 2 subtypes A and B using real-time PCR

We have developed and evaluated a new method to quantify human immunodeficiency virus type 2 (HIV-2) proviral DNA based on LightCycler real-time PCR. The assay has a detection limit of 5 copies/10(5) peripheral blood mononuclear cells (PBMC) and is insensitive to HIV-2 strain variability: HIV-2 subtypes A and B are both recognized and quantified. The intra- and interassay coefficients of variation range from 16 to 40% for high provirus concentrations (5 x 10(5) copies) and from 41 to 39% for low concentrations (5 copies). We used this method to compare the proviral DNA load and viral RNA load in plasma with clinical and immunological status for 29 patients infected by HIV-2 (subtype A in 17 and subtype B in 12). The proviral load (median, 201 copies/10(5) PBMC) was similar to that reported for HIV-1 infection. The median proviral loads did not correlate with the CD4(+) cell count categories and were as follows for CD4(+) cell counts of >400, 200 to 400, and <200 cells/mm(3), respectively: 121 copies/10(5) PBMC (n = 8; range, <5 to 712 copies/10(5) PBMC); 114 copies/10(5) PBMC (n = 9; range, <5 to 1,907 copies/10(5) PBMC); and 285 copies/10(5) PBMC (n = 12; range, 53 to 2,524 copies/10(5) PBMC). Proviral load did not correlate with plasma HIV-2 RNA positivity. As HIV-2 is considered to replicate less efficiently than HIV-1, these high proviral loads might be explained by the proliferation of infected cells.

The relative prognostic value of plasma HIV RNA levels and CD4 lymphocyte counts in advanced HIV infection

OBJECTIVE

It has been suggested that the plasma HIV RNA level is a better predictor of AIDS and death than the CD4 lymphocyte count. We assessed whether the prognostic value of plasma virus levels was different according to the CD4 count.

DESIGN

Prospective cohort study of HIV-infected patients followed for a median of 2.91 years (range, 0.02-4.54).

SETTING

Department of Infectious Diseases at Rigshospitalet, Copenhagen, Denmark.

PARTICIPANTS

A group of 255 HIV-infected individuals with an initial measurement of CD4 lymphocyte count and plasma HIV RNA.

MAIN OUTCOME MEASURE

Survival time.

RESULTS

The plasma HIV RNA (median 101410 copies/ml; range (range 200-7200000) and the CD4 lymphocyte count (median 250 cells x 10(6)/l; range 1-1247) were negatively correlated (Pearson r = -0.53; P < 0.00001). Of the 255 patients, 110 died during follow-up. Overall, a higher HIV RNA level was associated with increased risk of death, but the association was smaller in patients with lower CD4 lymphocyte counts (test for interaction P < 0.0001). In patients with CD4 count below 50 cells x 10(6)/l the association between HIV RNA and risk of death was not statistically significant (relative hazard per 10-fold higher HIV RNA level was 1.53; P = 0.11; adjusted for age and CD4 count) while that between the CD4 count and risk of death was highly significant (relative hazard per 50% lower CD4 count 1.38; P = 0.005; adjusted for age and HIV RNA level).

CONCLUSIONS

Patients were relatively lightly treated with antiretroviral drugs both before and during this study. In this situation, it appears that the HIV RNA level has a relatively weak association with risk of death in patients with advanced HIV infection and that the CD4 lymphocyte count is probably more useful in assessing prognosis.

Evaluation of HIV1 infection status by HIV1 PCR and culture methodologies in a small cohort of intravenous drug users

A small cohort of high-risk intravenous drug users (IVDU) from the Baltimore, MD, area was evaluated for HIV1 infection status and viral load. Quantitative dilution endpoint HIV1 DNA polymerase chain reaction (PCR) results, from HIV proviral DNA from quantitated peripheral blood mononuclear cell (PBMC) lysates, were compared to the dilution endpoint results for HIV PBMC micrococulture. The quantitative dilution endpoint HIV1 PCR was more rapid, sensitive and reproducible. In addition, an HIV1 capture RT-PCR technique was used to qualitatively detect the presence or absence of intact HIV1 virus in IVDU plasma and was compared with plasma culture detection, for HIV1 viraemia. Using the results of the PCR techniques, a rapid molecular assessment of the HIV1 infection status can be attained, which is important, as the IVDU population can be difficult to study prospectively. The PCR techniques can also be used to assess HIV1 burden as well as the potential effectiveness of antiviral therapies. These molecular techniques can be used to monitor the progression of HIV in patients and to evaluate the clinical effects of concurrent substance abuse.

Nested PCR assays with novel primers yield greater sensitivity to Tanzanian HIV-1 samples than a commercial PCR detection kit

To investigate the efficacy of the SK431/SK145 primer pair and two nested primer assays in amplifying African HIV-1 samples, a total of 35 Tanzanian PBMC samples were examined. These were assayed by two HIV-1 specific nested in-house PCR assays and a commercial HIV-1 PCR kit (GeneAmp) using SK431/SK145 as the primer pair. One of the nested PCR assays has been evaluated previously (old assay), whereas the modified assay was constructed from the HIV-1 sequence alignment released in August 1993. The modified nested primer assay showed increased sensitivity in the gag and env regions compared to the old nested primer assay. However, both the old and the modified nested primer assays displayed higher sensitivity for the detection of Tanzanian HIV-1 proviruses than the GeneAmp assay. When two regions were used (gag and env) as targets for the amplification, the modified nested primer assay detected 97.1% (34/35) of the proteinase K lysed samples, compared to 68.6% (24/35) using the SK431/SK145 primer pair (P < 0.01**). The results indicate that the SK431/SK145 primer pair may be less suitable when HIV-1 samples from Africa are analysed. The results also show that continuous modification of primer sequences can improve and maintain high sensitivity for the detection of highly divergent HIV-1 strains.

Utility of various commercially available human immunodeficiency virus (HIV) antibody diagnostic kits for use in conjunction with efficacy trials of HIV-1 vaccines

There is a need for human immunodeficiency virus (HIV) screening assays which will distinguish uninfected HIV vaccine recipients from HIV-infected individuals. Commercial screening kits were used to test serum samples from low- and high-risk participants in clinical trials before and after immunization with various recombinant HIV type 1 (HIV-1) envelope glycoprotein 120 (gp120) candidate vaccines. All kits were 100% sensitive in detecting HIV infection. Both Murex Single Use Diagnostic System and United Biomedical, Inc., HIV type 1 or 2 (HIV-1/2) enzyme immunoassay (EIA) kits, which detect antibodies to HIV-1 gp41, were 98 to 100% specific when used to screen baseline or recombinant gp120-vaccinated populations as vaccine-induced antibodies to gp120 were nonreactive in these tests. The Abbott HIVAB HIV-1 EIA (lysate of whole infected cells, reactive with anti-gp120 antibodies) gave high levels of reactivity due to vaccine-induced antibodies and a high baseline rate of false positives (12 of 83) among nonvaccinated high-risk volunteers. Assays containing only gp41 and p24 solid-phase components are compatible with gp120-based vaccines but are unlikely to be useful in a similar role for vaccines containing gp160, gp41, or gp120 plus p24 antigens. Efficacy trials must be designed in concert with available diagnostic screening assays to avoid problems caused by vaccine-induced seroconversion in high-risk populations.

Absence of recoverable infectious virus and unique immune responses in an asymptomatic HIV+ long-term survivor

We have studied a woman with transfusion-acquired HIV who appears to have contained infectious virus to consistently undetectable levels over a 13-year period without antiviral treatment. She received the infected transfusion for intra- and postpartum blood loss immediately after delivery of her second child in 1981. She had no acute febrile syndrome and has never had HIV-associated clinical signs or symptoms in the 13 years since infection. She was first tested and found positive for HIV antibodies in 1985, and the infected blood donor was diagnosed with AIDS in 1986 and died of AIDS-related complications in 1989. Two other recipients of packed erythrocytes from this donor (in 1980 and 1982) also became infected and were subsequently diagnosed with AIDS. Between January 1986 and April 1994, in the setting of continuous and unambiguous Western blot HIV-specific antibodies and intermittently positive low-level HIV DNA signal after polymerase chain reaction (PCR) amplification, more than 30 separate cell cocultures performed in several independent laboratories failed to yield evidence of infectious virus, despite special efforts to induce and detect HIV replication. Immunologically, a strong in vitro proliferative response to HIV envelope proteins also distinguished this subject from other asymptomatic HIV+ individuals.

HIV type 2 proviral load measured by quantitative polymerase chain reaction correlates with CD4+ lymphopenia in HIV type 2-infected individuals

The efficiency of detection of 2 sets of primer pairs from putatively conserved regions of the human immunodeficiency virus type 2 (HIV-2) genome were assessed in 86 seropositive individuals from The Gambia by nested polymerase chain reaction (PCR). HIV-2 long terminal repeat (LTR) target sequences were detected in DNA extracted from peripheral blood mononuclear cells (PBMCs) in 84 of 86 (97%) individuals whereas HIV-2 integrase (pol) gene sequences were detected in 39 of 41 (95%) individuals. The use of LTR target sequences and recombinant Pfu DNA polymerase, rather than Taq polymerase, in a modified secondary amplification reaction mediated the incorporation of 35S-labeled nucleotides in a quantitative radiometric assay. This sensitive assay was used to quantify HIV-2 proviral DNA in clinical samples and compared well with estimations by limiting end-point dilution of target molecules. A linear response between counts and the number of copies amplified from serial dilutions of pROD10 plasmid DNA (3-2000 copies) yielded a standard curve to allow extrapolation to clinical data. Increased levels of HIV-2 proviral DNA, expressed as copies per 10(5) CD4-positive lymphocytes, were associated with declining CD4 count in 63 adult patients (Spearman rank correlation, r = -0.71, n = 63, p < 0.001) and with the occurrence of HIV-related clinical disease. Kruskall-Wallis analysis of variance analysis showed the mean proviral copy number (log10) to be significantly different between groups (p < 0.001) where CD4 counts were grouped as < 200/mm3 (3.4 +/- 1.05 copies), 200-500/mm3 (2.84 +/- 0.93 copies), and > 500/mm3 (1.88 +/- 0.43 copies).(ABSTRACT TRUNCATED AT 250 WORDS)

Host-virus interaction as defined by amplification of viral DNA and serology in lentivirus-infected sheep

To correlate the presence of ovine lentivirus (OvLV) as detected by polymerase chain reaction (PCR) with detection of antibody, 42 sheep from a flock with enzootic OvLV infection were studied. The results of agar gel immunodiffusion (AGID), ELISA, and immunoblotting assays were compared, and leukocytes (blood, bone marrow, lymph node, and lung cells) were assessed for viral DNA by PCR using pol and LTR primers; amplified products were detected by specific DNA and RNA probes. Based on the number of animals that had detectable viral DNA, the specificities of AGID, ELISA, and immunoblotting were 77%, 92%, and 95 or 100% (depending on which criterion was used to interpret immunoblot results), respectively. Only in animals with OvLV-associated disease was OvLV DNA detected in leukocyte DNA prior to the amplification of virus in culture and only in this group was high titer antibody detected to the OvLV major surface (gp 105) and transmembrane (gp 55) antigens. Animals that were both antibody and PCR-negative lacked histopathologic evidence of disease. From this study there was no indication that OvLV infection without the development of antibody occurs, and detection of OvLV DNA in animals with weak or partial serological reactions likely indicates early OvLV infection rather than false-positive PCR results.

HIV-1 and the aetiology of AIDS

The belief that HIV-1 infection causes AIDs has been questioned, and the suggestion made that to know the correct cause of AIDS the incidence of disease in patients with and without risk behaviours and with and without antibody to HIV-1 must be known. We describe findings in such a cohort. In 715 homosexual men followed for a median of 8.6 years, all 136 AIDS cases occurred in the 365 individuals with pre-existing HIV-1 antibody. Most men negative for HIV-1 antibody reported risk behaviours but none developed any AIDS illnesses. CD4 counts fell in anti-HIV-1-positive men but remained stable in antibody-negative men, whether or not risk behaviours were present. The hypothesis that AIDS in homosexual men is caused not by HIV-1 infection but by drugs and sexual activity is rejected by these data. HIV-1 has an integral role in the pathogenesis of AIDS.

Possible supplemental mechanisms in the pathogenesis of AIDS

Multiple and diverse mechanisms have been proposed as supplements to the HIV-1 virus in the destruction of CD4+ cells and the pathogenesis of AIDS. But it is now realized that 100 times more CD4+ cells are infected with HIV-1 than was originally thought to be the case, and many antigen-presenting cells are infected as well. In addition to the direct cytopathic effect of the virus, one or a few supplemental mechanisms may well suffice to explain the progressive loss of CD4+ cells, e.g., the considerable variation in the virus and/or the destruction of uninfected CD4+ cells by one immunological mechanism or another. However, it is not yet possible to state confidently which additional mechanism(s) is important. Identification of the nature of this supplemental process has become essential for successful, nonharmful intervention.

Prognostic value of kinetic parameters of HIV isolation from peripheral blood mononuclear cells

To assess the correlations between clinical and biological stages of HIV infection and HIV isolation, peripheral blood mononuclear cells from 389 HIV-infected patients were studied by 30-day cocultures with normal lymphocytes. HIV isolation was successful in 279/389 patients (71.7%). Positive isolation was more frequent in CDC IV cases (82%) than in CDC II and III cases (63.6% and 78.4% respectively). There was a close correlation between culture positivity and serum beta 2-microglobulin, CD4+ cell counts and serum p24 antigen. The day of peak detection of reverse transcriptase activity or peak p24 antigen in coculture supernatants was selected as a coculture kinetic parameter. The day of peak detection of HIV in culture occurred earlier in CDC IV cases than in CDC II and III cases, and was a prognostic factor in AIDS progression at 2 years. These data suggest that in vitro parameters related to both viral burden and replicative capacity of HIV isolates are relevant indicators of disease progression.

Comparison of spot-blot and microtitre plate methods for the detection of HIV-1 PCR products

We have compared spot-blot methodology with a recently developed rapid microtitre plate assay for the specific detection of HIV-1 PCR products. We have studied blood specimens isolated from HIV-1 infected individuals (48 asymptomatic and 56 symptomatic patients). Mononuclear cells were isolated, lysed and processed for PCR. Both PCR product detection methods were carried out in parallel on all amplified samples. HIV-1 sequences were detected by spot-blot or microtitre plate hybridization in samples taken from 42/48 asymptomatic and 53/56 symptomatic subjects. Concordant results between the two detection methods were observed for 90 samples, with 81 positive and nine negative assays. On repeat evaluation of the 14 discordant samples, nine showed concordant positive results, near the limit of detection of the assay. Serial dilutions of ACH-2 cells were amplified, and the PCR products were detected using the microtitre plate assay, yielding semi-quantitative results. The sensitivity of this simple, rapid assay compares with that of more laborious DNA detection systems. This may become a useful tool in HIV-1 research and in the clinical care of seropositive individuals.

A sensitive viral capture assay for detection of plasma viremia in HIV-infected individuals

Human immunodeficiency virus was detected in the serum/plasma of individuals infected with human immunodeficiency virus (HIV) after capture of virions on microparticles coated with monoclonal antibodies to external and transmembrane proteins of HIV-1. We analyzed serial samples obtained from 6 individuals who seroconverted, 18 asymptomatic, and 12 AIDS patients. HIV-1 RNA was detected in all (29/29) seropositive samples and in 6 seronegative samples immediately preceding seroconversion. In contrast, HIV antigen was detected in 13/29 (45%) of seropositive samples. HIV-1 RNA was also detected in 3 antigen-negative samples from one individual 8-5 months prior to seroconversion and in one sample from another person 2 days before antigen positivity. The intensity of the polymerase chain reaction (PCR) signal paralleled the concentration of HIV antigen. Conversely, seropositive HIV antigen-negative samples gave a weaker PCR signal. HIV-1 RNA was detected in 10/18 (60%) samples from asymptomatic, HIV antigen-negative, individuals and in 11/12 (92%) specimens obtained from AIDS patients. The viral capture method may provide a sensitive, specific, and semiquantitative means of detecting circulating HIV at all stages of infection.