Ann-Charlotte Leandersson

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.

Treatment history and baseline viral load, but not viral tropism or CCR-5 genotype, influence prolonged antiviral efficacy of highly active antiretroviral treatment

Background:The efficacy of highly active antiretroviral treatment (HAART) in HIV-1 disease may vary between nucleoside-naive and experienced patients as well as between patients with different viral phenotypes and in different stages of disease. Objective:To investigate variables of importance for successful long-term viral suppression by analysing virological, clinical and immunological characteristics at initiation of protease inhibitor treatment on suppression of HIV RNA over 1 year. Design:An open, non-randomized, observational clinical study. Setting:Venhälsan, Department of Dermatovenereology, Söder Hospital, Stockholm, Sweden. Patients:A total of 147 unselected advanced patients with known HIV-1 infection for a mean of 7 years, of whom 37% had AIDS and who started treatment with a protease inhibitor during 1996. Interventions:All patients received HAART with at least two nucleoside analogues in combination with either indinavir (81%) or ritonavir (19%). The majority (77%) had been previously treated with nucleoside analogues for a mean of 39 months. Measurements:CD4+ lymphocyte count, plasma HIV-1 RNA, viral phenotype and HIV-1 coreceptor CCR-5 genotype at baseline. Viral load and CD4+ lymphocyte count were determined every 3 months. Results:Patients were analysed on an intention-to-treat basis. The mean CD4+ lymphocyte count at baseline was 170 × 106/l and the median viral load was 68 600 copies/ml. Heterozygosity for the Δ32 deletion of the CCR-5 gene (Δ32/wt) was found in 27%. MT-2 positive virus (syncytium-inducing) was isolated in 46%. Logistic regression revealed that nucleoside analogue experience and baseline log10 HIV-1 RNA were the only factors independently related to plasma HIV-1 RNA levels below 500 copies/ml after 1 year of treatment, which was found in 69%. Conclusion:The virological outcome after 1 year of HAART was strongly correlated to prior treatment history and baseline viral load, whereas CD4+ lymphocyte count, CCR-5 genotype and viral biological phenotype had less influence. The long-term antiviral efficacy of HAART was lowest in individuals with previous nucleoside analogue treatment and a high baseline viral load. In these individuals an even more aggressive treatment should be considered.

Induction of HIV-1 specific mucosal immune responses by DNA vaccination

DNA vaccination has been shown to induce immunity against several different pathogens including HIV‐1. The authors demonstrate here that administration of DNA vaccines via the intranasal route is sufficient to induce immune responses both at distal mucosal sites and systemically. Since transmission of HIV‐1 occurs largely across mucosal surfaces, the intranasal route provides a further means of application for DNA immunization.

DNA mucosal HIV vaccine in humans

This is a demonstration of immune activation by delivery of genetic vaccines in human mucosa. We analyzed the local and systemic responses in HIV-1 infected individuals following intraoral jet-injections of HIV-1 DNA constructs encoding the nef, rev, and tat regulatory genes. The immunological responses of the oral mucosa may be representative of other mucosal sites and was therefore selected for induction of mucosal reactivity by DNA immunization. The oral and intramuscular routes induced specific systemic T cell proliferative responses. Immunohistochemical analysis of oral biopsies 2 days after immunization revealed increased levels of granulocytes and T cells as well as expression of HLA-DR. T cell markers for CD3 +, CD4 + and CD8 + were significantly increased in the vaccinated mucosa. Vaccine-specific local and systemic antibodies were present during the immunization. However, increases were neither seen in the local or systemic titer nor in the B-cell accumulation in response to the immunizations. The presence of HIV-1 plasmid DNA was observed in mucosal biopsies as well as local proinflammatory T lymphocyte immune responses with predominantly IL-2 expression in the oral mucosal transudate.

Clinical and immunological benefits from highly active antiretroviral therapy in spite of limited viral load reduction in HIV type 1 infection.

Both naive and memory T lymphocyte responses are lost during advanced HIV infection. Treatment with highly active antiretroviral therapy (HAART) is associated with an increase in T lymphocytes and a reduction in viral load. However, the viral response to HAART in patients with low levels of helper T lymphocytes and a high viral load is often not satisfactory. We investigated the capacity of long-term HAART to reconstitute the immune system in severely ill patients. A nonselected longitudinal patient population with high baseline viral levels and CD4(+) cells below 100 x 10(6)/liter were monitored for 2 years during HAART. Markers to estimate the therapeutic effects included viral levels and cell surface markers representing naive and memory T lymphocytes as well as activation markers, B cells, NK cells, and clinical events. After 2 years of treatment, viral load was reduced to undetectable levels in 55% (viral responders, vRs) and less than 1 log (median value) from baseline in 45% (viral low responders, vLRs). Elevated numbers of memory and naive CD4(+) and CD8(+) cells as well as a decrease in activation markers were seen in both vRs and vLRs. However, the magnitude was greater in vRs. No differences in the clinical outcome were observed between vRs and vLRs. We conclude that most patients, even in advanced stages of HIV disease, benefited from HAART. The magnitude of the response was related to good viral reduction, but even patients with poor viral reduction had a recovery of naive and memory CD4(+) and CD8(+) cells. Even a small reduction in viral load is thus of importance for health and potentially also for years of survival.

MT-2 tropism and CCR-5 genotype strongly influence disease progression in HIV-1-infected individuals

Background:The β-chemokine receptor CCR-5 is the coreceptor for cellular entry by non-syncytium-inducing (NSI) HIV-1 strains that dominate early in infection. A 32 base-pair deletion (Δ32) in the CCR-5 gene renders this coreceptor non-functional. Heterozygosity for this deletion [Δ32/wild-type (wt)] is associated with slow disease progression. The purpose of this study was to document the combined impact on HIV-1 disease progression of the CCR-5 genotype and the biological phenotype of HIV-1 Methods:In a cross-sectional study of 258 HIV-1-infected Swedish individuals, the CCR-5 genotype (wt/wt or Δ32/wt) was determined by polymerase chain reaction and the biological phenotype [NSI or syncytium-inducing (SI)] of virus isolates was determined in the MT-2 cell assay. Clinical status, HIV-1 RNA levels in plasma, CD4+ lymphocyte counts, and rate of CD4+ lymphocyte decline, based on retrospective analysis of CD4+ lymphocyte counts, were also recorded. None of the individuals were treated with protease inhibitors. Results:The prevalence of the Δ32/wt genotype was 23%. Subjects with the Δ32/wt CCR-5 genotype more often carried SI virus than subjects with the wt/wt genotype (49 versus 35%; P = 0.067), but there were no differences between the two groups in prevalence of AIDS, viral load, CD4+ lymphocyte count or CD4+ slope. NSI virus isolates were found in 159 (62%) out of 258 individuals. Individuals with NSI had lower prevalence of AIDS (39 versus 19%; P < 0.01), higher CD4+ lymphocyte counts (289 ± 188 × 106/l versus 153 ± 162 × 106/l; P = 0.001), lower viral loads (median, 4.45 log10 versus 4.91 log10 copies/ml; P < 0.01) and a lower prevalence of the Δ32/wt genotype (19 versus 29%; P = 0.067) compared with individuals with SI virus. When the material was further subdivided, subjects with the Δ32/wt genotype and SI virus had the highest prevalence of AIDS (P < 0.001), lowest CD4+ lymphocyte count (P = 0.0001) and highest viral load (P = 0.023) whereas the opposite was true for subjects with the Δ32/wt genotype and NSI virus. A significantly higher proportion of subjects with NSI virus with Δ32/wt and wt/wt CCR-5 genotype had been immunized with recombinant gp160. Conclusion:In summary, the Δ32/wt CCR-5 genotype has a protective effect against HIV-1 disease progression that appears to be limited to individuals carrying HIV-1 variants with NSI phenotype. Immunization with recombinant gp160 tended to reduce the frequency of SI phenotypes.

CCR5 or CXCR4 is required for efficient infection of peripheral blood mononuclear cells by promiscuous human immunodeficiency virus type 2 primary isolates.

Primary human immunodeficiency virus type 2 (HIV-2) isolates are characterized by their ability to use a broad range of coreceptors, including CCR5, CXCR4, and several alternative coreceptors. However, the in vivo relevance of this in vitro promiscuity in coreceptor usage remains unclear. We set out to evaluate the relative importance of CCR5 and CXCR4 for infection of activated peripheral blood mononuclear cells (PBMC). PBMC from donors homozygous for wild-type CCR5 (CCR5(+/+) or CCR5Delta32 (CCR5(-/-)) were tested for their susceptibility to infection with 10 primary HIV-2 isolates with known coreceptor usage by parallel 50% tissue culture infectious dose (TCID50) titrations. Although all isolates, except one, were able to establish productive infection in CCR5(-/-) PBMC, the infection of these cells was inefficient for all isolates that were unable to use CXCR4. For CXCR4-using isolates there were only minor differences in TCID50 between CCR5(+/+) and CCR5(-/-) PBMC. When we compared the replication kinetics in PBMC from donors of the two genotypes we observed an average delay in replication onset of 9 days in the CCR5(-/-) PBMC. This study shows that HIV-2 can use alternative coreceptors for infection of PBMC, but that this infection is much less efficient than infection mediated by CCR5 or CXCR4. Thus, CCR5 and CXCR4 appear to be the major coreceptors for HIV-2 infection of PBMC.

Cross-reactive T-helper responses in patients infected with different subtypes of human immunodeficiency virus type 1.

Immunization with a recombinant glycoprotein 160 envelope immunogen derived from a virus of genetic subtype B induced strong specific T-helper cell responses in asymptomatic human immunodeficiency virus (HIV) carriers infected with subtypes B to G. This indicates that the HIV-specific T-helper immunity, which is the basis for development of antibodies and cytotoxic T lymphocytes, can be improved by both homologous and heterologous antigens. It also suggests that a particular immunogen can be effective against many different HIV strains.

Better preserved immune responses after immunization with rgp 160 in HIV‐1 infected patients treated with highly active antiretroviral therapy than in untreated patients with similar CD4 levels during at 2 years' follow‐up

To study the impact of effective highly active antiretroviral therapy (HAART) on the preservation of long‐term CD4 memory cells induced by vaccines in HIV‐1‐infected patients.

HIV type 1 DNA development during long-term supervised therapy interruption.

We studied the pattern of HIV-1 DNA development and the association to other HIV-related factors during long-term supervised therapy interruption (LT-STI). Fifteen patients were treated with long-time protease inhibitor-based antiretroviral therapy (PI-ART). They had HIV-1 RNA at <50 copies/ml over 33.4 (SD 9.5) months and CD4(+) cell counts of 875 (SD 415) x 10(6)/liter. A real-time polymerase chain reaction, amplifying fragments of the HIV-1 pol gene and the human albumin gene simultaneously, was used to quantify HIV-1 DNA molecules in CD4(+) cells. The quantity of HIV-1 DNA in CD4(+) cells increased during LT-STI in all 15 patients, with an average doubling time of 2 months. Tentatively, three patterns were observed: rapid initial increase with subsequent stabilizing levels, rapid continuous increase, and slow increase. The HIV-1 DNA slope was positively related to the HIV-1 RNA maximum and steady state level and the baseline HIV-1 DNA value. It was inversely related to the decrease in CD4(+) cells both before the start of PI-ART and during the LT-STI. To conclude, HIV-1 DNA persists in infected CD4(+) cells despite long-term effective PI-ART and will increase after therapy interruption. The most important clinical predictor of long-term STI failure was the rapid CD4(+) cell decline before PI-ART. In patients with a steep pre-PI-ART slope it may be prudent to continue treatment and not initiate therapy interruption.