Loss of immune homeostasis dictates SHIV rebound after stem-cell transplantation.

The conditioning regimen used as part of the Berlin patient's hematopoietic cell transplant likely contributed to his eradication of HIV infection. We studied the impact of conditioning in simian-human immunodeficiency virus-infected (SHIV-infected) macaques suppressed by combination antiretroviral therapy (cART). The conditioning regimen resulted in a dramatic, but incomplete depletion of CD4+ and CD8+ T cells and CD20+ B cells, increased T cell activation and exhaustion, and a significant loss of SHIV-specific Abs. The disrupted T cell homeostasis and markers of microbial translocation positively correlated with an increased viral rebound after cART interruption. Quantitative viral outgrowth and Tat/rev-induced limiting dilution assays showed that the size of the latent SHIV reservoir did not correlate with viral rebound. These findings identify perturbations of the immune system as a mechanism for the failure of autologous transplantation to eradicate HIV. Thus, transplantation strategies may be improved by incorporating immune modulators to prevent disrupted homeostasis, and gene therapy to protect transplanted cells.

Replicating adenovirus HIV/SIV recombinant priming alone or in combination with a gp140 protein boost results in significant control of viremia following a SHIV89.6P challenge in Mamu-A*01 negative rhesus macaques.

Previously, replicating adenovirus type 5 host range (Ad5hr)-HIV/SIV recombinant priming in combination with SIV envelope boosting, resulted in significant, durable protection in 39% of rhesus macaques after SIVmac251 challenge. Both Env-specific antibody mediating ADCC, and cellular immunity correlated with protection. Here we evaluate the relative immunogenicities of novel HIV proteins and their contribution to protection in a SHIV89.6P model. All groups were primed with Ad-HIVenv89.6P, SIVgag239, and SIVnef239 recombinants. One group was not boosted, one received HIV89.6Pgp140DeltaCFI protein, and one a novel HIV-1 poly-peptide "peptomer". The HIV89.6Pgp140DeltaCFI protein in adjuvant strongly boosted Env-specific antibody and memory T cell responses in blood and tissue, resulting in significant reductions in acute and set point viremia. Macaques not boosted, showed a significant reduction in set point viremia, a full 32 weeks after the last Ad priming immunization. The HIV peptomer-boosted group showed a trend toward chronic viremia reduction, but was not protected.

Effects of total lymphoid irradiation on SIV-infected macaques.

The identification of antiretroviral drugs that prevent, or delay for extended periods, progression of HIV-related disease has been of limited success. Because the number of HIV-infected people continues to increase, other therapeutic approaches must be tested. Using simian immunodeficiency virus (SIV)-infected macaques in a feasibility study, total lymphoid irradiation (TLI) was administered in fractionated doses to the supradiaphragmatic and then the infradiaphragmatic lymph nodes until a cumulative dose of 34.2 Gy was achieved in each field. During treatment and for more than 1 year of follow-up, the effects of TLI on various virological, hematological, and immunological parameters were evaluated and compared to those of similarly treated, uninfected macaques. Despite sustained low numbers of CD4+ lymphocytes (< 100/microliters blood) during treatment, TLI was well tolerated, did not result in intercurrent infections, and more importantly, induced a transient decrease in viral burden and did not exacerbate disease. Remarkably, this lack of disease progression and apparent containment of SIV replication were maintained despite persistent failure of PBMCs to respond to mitogen stimulation. Because SIV (and HIV) requires activated lymphocytes to replicate, failure of PBMCs to respond fully to stimuli may have contributed to restricting virus replication. This idea was supported by in vitro experiments in which infection of PBMCs before TLI produced higher levels of cell-free SIV than those obtained during or after TLI. Last, repopulation of peripheral blood and lymph nodes with lymphocytes paralleled that observed in uninfected control animals. The results indicate that (1) immunosuppression alone is not sufficient to induce progression to AIDS, (2) SIV infection does not undermine the ability of the immune system to regenerate new cells during the clinically latent phase, and (3) further evaluation of TLI or other immunosuppressive regimens as potential therapies for HIV disease is warranted.

Analysis of the carbon dioxide laser plume for simian immunodeficiency virus.

To determine the viability of the immunodeficiency virus in the laser plume after carbon dioxide (CO2) laser irradiation, multiple samples of culture medium containing concentrated simian immunodeficiency virus (SIVMAC at 1000 TCID50 cultured from HUT 78 cells) were irradiated with a continuous-wave CO2 laser at variable irradiances (from 400 W/cm2 for 5 seconds to 1600 W/cm2 for 300 seconds). The resultant plume was collected and cultured for the presence of SIV. A positive control consisted of handling an infected specimen identically to the test specimens, with the exception of CO2 laser irradiation. All test cultures remained negative over an 8 week incubation period, while the control was positive for viable SIV within 7 days. These results suggest that SIV is not viable in the laser plume after CO2 laser irradiation. Further investigation is necessary before extrapolating these results to the human immunodeficiency virus (HIV).

Inactivation of viruses with photoactive compounds.

The transmission of human immunodeficiency virus (HIV-1) and other enveloped virus by blood transfusion is a major concern. Photosensitive dyes such as hematoporphyrin derivative (HPD), dihematoporphyrin ether (DHE), benzoporphyrin derivatives (BPD), extended ring porphyrins, sapphyrins and texaphyrins, and various cyanines were used with viral cultures to test the feasibility of using those light-excitable dyes to kill virus. A photodynamic flow cell was used to irradiate viral suspensions or viral infected cells in culture media or in whole blood. Herpes virus (HSV-1) was used to screen compounds. Effective compounds were subsequently tested for their ability to kill HIV-1, CMV, and SIV in culture medium and in blood and proved to effectively kill free virus and infected cells at significant viremias. Irradiation was achieved with a filtered xenon light source and/or tunable dye laser. Concentrations of dyes at 10 times viral kill dose were irradiated in blood which was tested for damage to erythrocytes (RBC), platelets, and blood proteins. No damage to RBC, complement factors, and immunoglobulins was evident immediately after photodynamic treatment. Platelet condition is minimally modified with time. Photodynamic treatment of blood appears to be a feasible means of eradicating virus and some protozoans from blood.