Adoptive Transfer of Engineered Rhesus Simian Immunodeficiency Virus-Specific CD8⁺T Cells Reduces the Number of Transmitted/Founder Viruses Established in Rhesus Macaques

Abstract

AIDS virus infections are rarely controlled by cell-mediated immunity, in part due to viral immune evasion and immunodeficiency resulting from CD4؉ T-cell infection. One likely aspect of this failure is that antiviral cellular immune responses are either absent or present at low levels during the initial establishment of infection. To test whether an extensive, timely, and effective response could reduce the establishment of infection from a high-dose inoculum, we adoptively transferred large numbers of T cells that were molecularly engineered with anti-simian immunodeficiency virus (anti-SIV) activity into rhesus macaques 3 days following an intrarectal SIV inoculation. To measure in vivo antiviral activity, we assessed the number of viruses transmitted using SIVmac239X, a molecularly tagged viral stock containing 10 genotypic variants, at a dose calculated to transmit 12 founder viruses. Single-genome sequencing of plasma virus revealed that the two animals receiving T cells expressing SIV-specific T-cell receptors (TCRs) had significantly fewer viral genotypes than the two control animals receiving non-SIV-specific T cells (means of 4.0 versus 7.5 transmitted viral genotypes; P ‫؍‬ 0.044). Accounting for the likelihood of transmission of multiple viruses of a particular genotype, the calculated means of the total number of founder viruses transmitted were 4.5 and 14.5 in the experimental and control groups, respectively (P ‫؍‬ 0.021). Thus, a large antiviral T-cell response timed with virus exposure can limit viral transmission. The presence of strong, preexisting T-cell responses, including those induced by vaccines, might help prevent the establishment of infection at the lower-exposure doses in humans that typically transmit only a single virus. IMPORTANCEThe establishment of AIDS virus infection in an individual is essentially a race between the spreading virus and host immune defenses. Cell-mediated immune responses induced by infection or vaccination are important contributors in limiting viral replication. However, in human immunodeficiency virus (HIV)/SIV infection, the virus usually wins the race, irreversibly crippling the immune system before an effective cellular immune response is developed and active. We found that providing an accelerated response by adoptively transferring large numbers of antiviral T cells shortly after a high-dose mucosal inoculation, while not preventing infection altogether, limited the number of individual viruses transmitted. Thus, the presence of strong, preexisting T-cell responses, including those induced by vaccines, might prevent infection in humans, where the virus exposure is considerably lower. T he CD8ϩ T cell plays an important role in control of AIDS viruses, i.e., human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) (1-10). However, in most cases, CD8 ϩ T-cell responses, whether consisting of responses to infection developed de novo or to prior vaccination, are unable to prevent development of persistent, disseminated infection....

CXCR5-Dependent Entry of CD8 T Cells into Rhesus Macaque B-Cell Follicles Achieved through T-Cell Engineering

“…Other adoptive transfer studies relying on longer, more extensive in vitro selection and expansion of naturally occurring SIV-specific T-cell clones in culture rather than the limited ex vivo expansion made possible by engineering T cells presented here have observed no detectable persistence in either blood or tissues other than the lung (47,48). Recently, we applied T-cell engineering techniques to express CCR7/CD62L on T cells and observed limited, but unequivocal trafficking to lymph nodes and avoidance of the lung, demonstrating targeting of infused T cells to lymphoid tissues in a nonhuman primate system (43). Here, we extend this concept with cells that had less extensive expansion ex vivo than used in our prior CCR7/CD62L study, and we observed greater frequencies of infused cells in the secondary lymphoid tissues.…”

“…The frequencies of the infused T cells in PBMC from necropsy samples were decreased approximately 10-fold from those of the 15-min postinfusion samples, ranging from 0.3 to 1% (n ϭ 6; x ϭ 0.7%; SD ϭ 0.25%), suggesting movement of the infused cells out of the peripheral circulatory system. One common observation in adoptive transfer studies is that bronchoalveolar lavage sampling of animals contain high frequencies of infused cells, presumed to be "trapped" in the lung (43,47,48). Flow cytometry of CD3 ϩ cells isolated from the prenecropsy bronchoalveolar lavage samples showed a high frequency of infused cells relative to the endog- enous T cells, from 7 to 76% (n ϭ 6; x ϭ 54%; SD ϭ 24%) consistent with retention of some of the infused cells in the lung.…”

“…The ability to genetically engineer T cells with genes of interest, especially T-cell receptors (TCR) and chimeric antigen receptors, using retroviral and lentiviral vectors is a powerful technique, from the initial human gene therapy trial 25 years ago to its current use in cellular immunotherapeutics against cancer (40)(41)(42). In a pilot study, we engineered SIV-specific T cells with CCR7 and CD62L which preferentially localized to lymph nodes in a rhesus macaque adoptive transfer system (43). For this study, we tested whether circulating CD8 T cells can be engineered to enter B-cell follicles in rhesus macaques by ectopically expressing CXCR5 on unselected bulk peripheral blood-derived CD8 T cells, expanding the engineered T cells ex vivo, and infusing the autologous cells back into donor animals.…”

The dynamics of simian immunodeficiency virus after depletion of CD8+ cells

“…17 Meanwhile, experiments designed to change the numbers of CD8+ T cells in circulation have an important (but variable) impact on viral load. These include experiments to increase the number of CD8+ T cells, such as infusion of these cells [18][19][20][21][22][23][24] and studies of vaccines leading to large expansions of the circulating CD8+ T-cell counts. 25,26 The opposite approach, trying to reduce CD8+ cells, by infusion of depleting antibodies, has also been attempted in simian immunodeficiency virus (SIV) animal models, usually leading to significant increases in viral load.…”

The Frequency of Vaccine-Induced T-Cell Responses Does Not Predict the Rate of Acquisition after Repeated Intrarectal SIVmac239 Challenges in Mamu-B*08 + Rhesus Macaques

“…Indeed, mounting evidence suggests that lentivirus-specific CD8 ϩ T cells can do more than reduce viremia in productively infected individuals. For instance, a recent study has shown that adoptively transferring large quantities of SIV-specific CD8 ϩ T cells into RMs 3 days after a high-dose IR challenge with SIV can reduce the number of transmitted/founder viruses in infected animals (56). Although this approach did not prevent the establishment of productive infection, it lends support to the notion that high frequencies of vaccine-elicited CD8 ϩ T cells situated at relevant sites of virus replication can intercept a nascent infection before it becomes systemic.…”