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Volume 6 Supplement 3

AIDS Vaccine 2009

P18-14 LB. Vacc-4x HIV p24-like peptide vaccine-associated increase of CD4 T-cells in chronically infected HIV-1 patients on antiretroviral therapy

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Background

Since its implementation more than a decade ago combination Antiretroviral Therapy (ART) has had a dramatic effect on HIV-1 induced mortality and morbidity. However, 15-20% of the patients initiating ART do not regain CD4 T-cells despite an effective suppression of HIV1-mRNA levels in blood. The incomplete therapeutic effect leaves these patients at elevated risk of disease complications and death. Attempts to reduce clinical events through IL-2 induced stimulation of CD4 T-cells in the ESPRIT and SILCAAT studies have not proven to be successful. Until further research has given better opportunities for a successful direct induction of functional CD4 cells a logical alternative may be to increase CD4 counts indirectly by improving anti-HIV effect while on ART using antigen-specific immune stimulation with an effective HIV-vaccine.

Methods

In a Phase II trial with Vacc-4x, a synthetic and specific peptide vaccine to HIV-1 p24Gag, the increase of CD4 cells was studied in 37 chronically infected HIV patients on ART and with varying baseline CD4 T-cell counts. The median duration of ART prior to Vacc-4x immunization was 4.5 years and preART CD4 counts were median 295 cells/uL.

Results

The average increase of CD4 counts was 9% (P < 0,05) above baseline at 585 cell/uL (mean) 6 weeks after immunization. For patients with baseline CD4 level <500 cells/uL (n = 11) the increase was 25% (P < 0,05) or 105 cells/uL. Only a few patients had a baseline CD4 count <400 (n = 3) with an average increase of 32% (NS).

Conclusion

Patients on ART immunized with Vacc-4x experienced increased CD4 counts. The effect appeared more pronounced in patients with lower baseline CD4 counts (<400-500). In a previous study (ACTG 384) CD4 increase for patients (preART CD4<300) was minimal after 120 weeks on ART (RobbinsCID 2009,48, 350-61).

Author information

Correspondence to P Bengtsson.

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Open Access This article is published under license to BioMed Central Ltd. This is an Open Access article is distributed under the terms of the Creative Commons Attribution 2.0 International License (https://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Bengtsson, P., Baksaas, I., Sommerfelt, M. et al. P18-14 LB. Vacc-4x HIV p24-like peptide vaccine-associated increase of CD4 T-cells in chronically infected HIV-1 patients on antiretroviral therapy. Retrovirology 6, P413 (2009). https://doi.org/10.1186/1742-4690-6-S3-P413

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Keywords

  • Peptide Vaccine
  • Logical Alternative
  • Induce Mortality
  • Induce Stimulation