DNA immunization with HIV early genes in HIV type 1-infected patients on highly active antiretroviral therapy

The aim of this study was to evaluate the immunological responses induced by DNA plasmids containing HIV regulatory genes administered in combination in HIV-1-infected patients with pretreatment with highly active antiretroviral treatment (HAART). The study is a double-blind, randomized, and placebo-controlled study, including 15 asymptomatic HIV-1-infected patients on stable HAART for at least 6 months and with plasma HIV RNA levels below 50 copies/ml. Ten patients received a combination of rev, tat, and nef intramuscularly (im) at weeks 0, 4, and 16 at increasing doses giving totals of 300 (100 x 3), 900 (300 x 3), and 1800 (600 x 3) micrograms DNA. Five patients received saline in the same amounts im. Antigen-specific cytotoxic T lymphocyte (CTL) levels were preserved or increased and new T lymphocyte proliferative responses were induced in the group immunized with the HIV DNA genes. No increase in antibody levels was noted. Despite a 10-fold higher vaccine dose, patients on HAART did not respond better to vaccination compared to non-HAART patients included in a previous study where the genes were administered separately. Combining the regulatory genes rev, tat, and nef in increasing doses may reduce the anticipated augmentation of HIV-specific T cell proliferative and CTL responses. Viral suppression did not seem to further improve the initial vaccine responses of patients with comparable CD4 levels.

HIV subtypes and recombination strains--strategies for induction of immune responses in man

Clinical and experimental studies of HIV-1 subcomponents were made in order to increase their immunogenicity. HIV subtype envelopes A, B and C have been compared and a detailed analysis made by peptides of the coreceptor-ligand interactions. We identified a direct interaction between HIV-1 envelope and a cellular receptor at the amino acid level. Both the viral subtype and its tropism appeared to influence inhibition of infection. Genetic immunization induced new cytotoxic responses while proteins appeared to efficiently boost previous responses. One HIV-1 subtype B antigen was strongly immunogenic in a human immunotherapeutic trial and permitted better survival at 2 years of the study in patients with poor prognosis.

Cellular cytotoxic response induced by DNA vaccination in HIV-1-infected patients

BACKGROUND

DNA vaccination is known to generate immune responses against HIV-1 in animal models. We aimed to assess the efficacy of DNA vaccination in induction of immune responses in HIV-1-infected human beings.

METHODS

Nine symptom-free HIV-1-infected patients were immunised with DNA constructs encoding the nef, rev, or tat regulatory genes of HIV-1. The patients were selected for having no or low antibody reactivities to these antigens. HIV-1-specific cytotoxic T-lymphocytes (CTLs), precursor frequencies, and antigen-specific proliferative responses were measured before, during, and after three immunisations over 6 months.

FINDINGS

Cellular immune reactivities against the HIV-1 regulatory proteins were absent or low before DNA immunisation. DNA vaccination induced detectable memory cells in all patients and specific cytotoxicity in eight patients. CTLs were MHC-class-I restricted and mainly of CD8+ origin. In three patients the cellular activity was transient, decreasing after an initial response.

INTERPRETATION

DNA immunisation with HIV-1 genes can induce specific cellular responses in human beings with no apparent side-effects. It is theoretically possible that HIV-1-specific cytotoxic responses to regulatory proteins could lead to infected cells being eliminated before they have released new viral particles. However, it is possible that the patients we selected responded less than would non-selected or non-infected individuals. The small number of patients presented here does not allow generalisation of our findings.

Diagnosis of perinatally acquired HIV-1 infection using an IgA ELISA test

The clinical utility of the detection of anti-HIV-1 IgA antibodies using a modified commercial ELISA (EIA) test for the early diagnosis of perinatally acquired HIV-1 infection was evaluated. One hundred and seventeen sera were obtained from 86 infants born to HIV-1-infected mothers and tested for HIV IgA antibodies by an ELISA test (third generation) after removal of IgG with recombinant protein G. Infants were classified according to the Center for Disease Control and Prevention's (CDC) classification system after 15 months of age; 46 were classified as HIV-infected children and 40 as uninfected. HIV-IgA antibodies were detected in 53 of 64 serum samples from all infected children. No significant differences were observed in IgA detection among symptomatic or asymptomatic infected children. However, when analyzed by age a significant difference was observed in IgA detection when children who were over 6 months of age were compared with the younger group (Fisher exact test, p = 0.0000053). All 53 samples from 40 noninfected children were IgA-negative. Statistical analysis was assessed comparing IgA results with HIV infection status as the gold standard. Sensitivity (95%) and specificity (100%), positive predictive value (100%), and negative predictive value (94%) of IgA antibody determination were analyzed taking into account only one sample per child and only children older than 6 months. Positive likelihood ratio was 95.9% and negative likelihood ratio was 94%. Test efficiency was 97%. The detection of IgA HIV antibodies using EIA is an effective method for early diagnosis of HIV-infected infants in comparison with conventional IgG HIV antibody tests. It is a simple and inexpensive method that could be used in both developed and developing countries.

Immunodominant glycoprotein 41 epitope identified by seroreactivity in HIV type 1-infected individuals

A highly conserved gp41 epitope (amino acid sequence ELDKWA) has been described to elicit antibodies neutralizing a broad variety of HIV-1 strains. We analyzed the antibody reactivity of HIV-1-infected individuals from Argentina and Sweden to overlapping synthetic peptides covering aa647-684 of HIV-1 MN gp41. An immunodominant antigenic determinant was discovered in the C-terminal region adjacent to the ELDKWA sequence. Most of the sera from both Argentina and Sweden reacted only with peptides representing this region. Two other patterns of reactivity were also observed: some sera reacted only with peptides spanning the central region of gp41, including the ELDKWA sequence; other sera reacted with both the central and C-terminal regions. Differences in reactivity were noted between Argentinian and Swedish sera in terms of peptides covering the central region. In addition, to determine the amino acids essential for antibody binding, seroreactivity against a set of substitution peptides covering the immunodominant epitope was studied. Results obtained indicated that carboxyl amino acids WNWFDI close to the ELDKWA sequence were the most important for antibody binding. Ability of sera, tested for peptide reactivity, to neutralize HIV-1 was also analyzed. High antibody reactivity to the central region was frequently found in sera with high neutralizing titers. This observation was not seen when seroreactivity to peptides spanning the C-terminal region was analyzed. These results suggest that the immunodominant epitope C terminal to the ELDKWA sequence is not involved in inducing neutralizing antibodies.

Retrospective study of children born to HIV-1-infected mothers in a pediatric hospital in Argentina

The aim of this retrospective study, which included 103 children born to human immunodeficiency virus type 1 (HIV-1)- infected mothers, is to initiate a database on HIV-infected children, which has to date been unavailable in Argentina. All HIV-1 seropositive children admitted to the Pedro de Elizalde Children's Hospital in Buenos Aires from March 1, 1987, to December 31, 1992, were enrolled in this study. The number of patients enrolled dramatically increased each year during the period of study. Of the 60 infected children, 22 (36.66%) have died with a clinical diagnosis of HIV-1 infection; in 10 of those children HIV infection was also confirmed by P24 antigenemia and/or polymerase chain reaction (PCR): 20 qualified for the Centers for Disease Control and Prevention (CDC) P2D class (P2D1 = 7, P2D2 = 10, P2D3 = 3), 1 for P2C, and 1 for P2A, whose cause of death was pneumonia. The mean age of death was 14.8 months, 18 (82%) died before 18 months. When immunoglobulin G (IgG), IgM, and IgA levels were determined according to age and clinical status, significant differences (P < 0.005) were observed when both asymptomatic and symptomatic infected children (P1, P2) were compared with noninfected children (P3). A significant difference was also obtained between those children who qualified for P2 classification prior to 12 months of age who died early (at or prior to 25 months) and those who reached stage P2 after 12 months of age and have survived to date (X2 = 24.73, p < 0.0001; RR = 5.83, 2.52 < RR < 13.49).