Genetic Evaluation of Suspected Cases of Transient HIV-1 Infection of Infants

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Recall T cell responses to HIV-1 antigens are used as a surrogate for endogenous cellular immune responses generated during infection. Current methods of identifying antigen-specific T cell reactivity in HIV-1 infection use bulk peripheral blood mononuclear cells (PBMC) yet ignore professional antigen-presenting cells (APC) that could reveal otherwise hidden responses. In the present study, peptides representing autologous variants of major histocompatibility complex (MHC) class I-restricted epitopes from HIV-1 Gag and Env were used as antigens in gamma interferon (IFN-␥) enzyme-linked immunosorbent spot (ELISpot) and polyfunctional cytokine assays. Here we show that dendritic cells (DC) enhanced T cell reactivity at all stages of disease progression but specifically restored T cell reactivity after combination antiretroviral therapy (cART) to early infection levels. Type 1 cytokine secretion was also enhanced by DC and was most apparent late post-cART. We additionally show that DC reveal polyfunctional T cell responses after many years of treatment, when potential immunotherapies would be implemented. These data underscore the potential efficacy of DC immunotherapy that aims to awaken a dormant, autologous, HIV-1-specific CD8 ؉ T cell response. IMPORTANCEAssessment of endogenous HIV-1-specific T cell responses is critical for generating immunotherapies for subjects on cART. Current assays ignore the ability of dendritic cells to reveal these responses and may therefore underestimate the breadth and magnitude of T cell reactivity. As DC do not prime new responses in these assays, it can be assumed that the observed responses are not detected without appropriate stimulation. This is important because dogma states that HIV-1 mutates to evade host recognition and that CD8 ؉ cytotoxic T lymphocyte (CTL) failure is due to the inability of T cells to recognize the autologous virus. The results presented here indicate that responses to autologous virus are generated during infection but may need additional stimulation to be effective. Detecting the breadth and magnitude of HIV-1-specific T cell reactivity generated in vivo is of the utmost importance for generating effective DC immunotherapies.

Section: Methodsmentioning

confidence: 99%

“…cDNA synthesis was performed by using primers Nef3 (33) and RT2 (34) with SuperScript III reverse transcriptase (200 U/ml; Invitrogen, Carlsbad, CA). Endpoint dilution methodology was used to dilute reaction mixtures to ϳ1 copy per 3 to 5 reactions, followed by direct sequencing to avoid detection of PCRinduced mutations (35).…”

Section: Methodsmentioning

confidence: 99%

Dendritic Cells Restore CD8⁺T Cell Reactivity to Autologous HIV-1

Smith

Mailliard

Larsen

et al. 2014

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“…More controversial is the pattern of transiently viremic individuals who are intermittently positive for virus load or immune responses. Early evidence for transient viremia in pediatric cases was ruled out due to sample mislabeling (12), but there is additional evidence for low-level or transient viremia prior to acute HIV viremia (10) or in the context of antiretroviral treatment (18). Infection of macaques with many simian immunodeficiency virus (SIV) or simian-human immunodeficiency virus (SHIV) isolates also results in variable infection patterns, and transient or low-level infections have occurred following low-dose challenges (31,35,52,55).…”

mentioning

confidence: 99%

Evidence for Persistent, Occult Infection in Neonatal Macaques following Perinatal Transmission of Simian-Human Immunodeficiency Virus SF162P3

Jayaraman¹,

Zhu²,

Misher

et al. 2007

To model human immunodeficiency virus (HIV) perinatal transmission, we studied infection of simianhuman immunodeficiency virus (SHIV) SF162P3 in 10 pregnant Macaca nemestrina females and their offspring. Four of nine infants born to and suckled by these dams had evidence of infection, a transmission rate of 44.4% (95% confidence interval, 13.7% to 78.8%). We quantified transplacentally acquired and de novo Env-specific immunoglobulin G (IgG), IgM, and neutralizing antibodies in newborns. Transmission of escape variants was confirmed. In utero infection (n ‫؍‬ 1) resulted in high viremia, depletion of peripheral CD4 ؉ T cells, and rapid evolution of env in blood and tissues. Peripartum or postpartum SHIV infection (n ‫؍‬ 3) resulted in postacute viral control that was undetectable by very sensitive multiplex PCR, despite increasing antibodies. Seropositive infants with highly controlled viremia had homogeneous peripheral blood env sequences, and their tissues had <3 copies per million cells. A high incidence of seropositive virus-low or -negative SHIV infection in infant macaques has implications for HIV type 1 perinatal transmission and detection.

“…However, a prerequisite for the acquisition of meaningful data, particularly with regard to predictors of contagion in the index seropositive partner, is the ability to confirm, with a high level of confidence, epidemiological linkage of HIV-1 transmission between members of all putative transmission pairs. Molecular analyses of suspected transmission links have been widely used to characterize localized HIV-1 outbreaks, mother-to-infant transmission, sexual transmission, sharing of contaminated needles, donation of contaminated blood, receipt of contaminated clotting reagent, nosocomial transmissions from health care workers, and intrafamilial contacts (1,4,5,6,13,18,21,29,36,42,44). In all of these cases, the establishment of epidemiological linkage relied on the documentation of closer genetic relatedness between viruses infecting the suspected transmission pair(s) compared to control viruses isolated from unrelated individuals in the same region.…”

mentioning

confidence: 99%

Molecular Epidemiology of Human Immunodeficiency Virus Type 1 Transmission in a Heterosexual Cohort of Discordant Couples in Zambia

Trask¹,

Derdeyn²,

Fideli

et al. 2002

136

124

Most human immunodeficiency virus type 1 (HIV-1) transmissions in sub-Saharan Africa are believed to occur between married adults who are discordant for their HIV-1 infection status; however, no studies to date have investigated the molecular epidemiology of such transmission events. Here we report the genetic characterization of HIV-1 strains from 149 transmission pairs that were identified prospectively in a cohort of discordant couples in Lusaka, Zambia. Subgenomic gag, gp120, gp41, and/or long terminal repeat regions were amplified by PCR analysis of uncultured blood samples from both partners and sequenced without interim cloning. Pairwise genetic distances were calculated for the regions analyzed and compared to those of subtypespecific reference sequences as well as local controls. Sequence relationships were also examined by phylogenetic tree analysis. By these approaches, epidemiological linkage was established for the majority of transmission pairs. Viruses from 129 of the 149 couples (87%) were very closely related and clustered together in phylogenetic trees in a statistically highly significant manner. In contrast, viruses from 20 of the 149 couples (13%) were only distantly related in two independent genomic regions, thus ruling out transmission between the two partners. The great majority (95%) of transmitted viruses were of subtype C origin, although representatives of subtypes A, D, G, and J were also identified. There was no evidence for extensive transmission networks within the cohort, although two phylogenetic subclusters of viruses infecting two couples each were identified. Taken together, these data indicate that molecular epidemiological analyses of presumed transmission pairs are both feasible and required to determine behavioral, virological, and immunological correlates of heterosexual transmission in sub-Saharan Africa with a high level of accuracy.