Jodi Anderson

Persistent HIV-1 replication is associated with lower antiretroviral drug concentrations in lymphatic tissues

Significance We show that HIV continues to replicate in the lymphatic tissues of some individuals taking antiretroviral regimens considered fully suppressive, based on undetectable viral loads in peripheral blood, and that one mechanism for persistent replication in lymphatic tissues is the lower concentrations of the antiretroviral drugs in those tissues compared with peripheral blood. These findings are significant because they provide a rationale and framework for testing the efficacy of new agents and combinations of drugs that will fully suppress replication in lymphatic tissues. More suppressive regimens could improve immune reconstitution, as well as provide the effective regimens needed for functional cure and eradication of infection. Antiretroviral therapy can reduce HIV-1 to undetectable levels in peripheral blood, but the effectiveness of treatment in suppressing replication in lymphoid tissue reservoirs has not been determined. Here we show in lymph node samples obtained before and during 6 mo of treatment that the tissue concentrations of five of the most frequently used antiretroviral drugs are much lower than in peripheral blood. These lower concentrations correlated with continued virus replication measured by the slower decay or increases in the follicular dendritic cell network pool of virions and with detection of viral RNA in productively infected cells. The evidence of persistent replication associated with apparently suboptimal drug concentrations argues for development and evaluation of novel therapeutic strategies that will fully suppress viral replication in lymphatic tissues. These strategies could avert the long-term clinical consequences of chronic immune activation driven directly or indirectly by low-level viral replication to thereby improve immune reconstitution.

Large number of rebounding/founder HIV variants emerge from multifocal infection in lymphatic tissues after treatment interruption

Significance Antiretroviral therapy (ART) effectively suppresses HIV replication; however, treatment cannot be stopped, because latently infected CD4+ T cells will rekindle infection. As one estimate of the size of the pool of latently infected cells that must be purged for cure, we asked whether recrudescent infection is the result of reactivation from one or a larger number latently infected cells. We briefly stopped ART in fully suppressed patients to see how widespread new infections were in the lymphoid tissues (LTs) and how diverse rebounding/founder viruses were in peripheral blood. Recrudescent infection was detectable in multiple different LTs, and the population was genetically diverse, consistent with reactivation from a larger number of cells. These findings underscore the challenges facing strategies to eradicate HIV infection. Antiretroviral therapy (ART) suppresses HIV replication in most individuals but cannot eradicate latently infected cells established before ART was initiated. Thus, infection rebounds when treatment is interrupted by reactivation of virus production from this reservoir. Currently, one or a few latently infected resting memory CD4 T cells are thought be the principal source of recrudescent infection, but this estimate is based on peripheral blood rather than lymphoid tissues (LTs), the principal sites of virus production and persistence before initiating ART. We, therefore, examined lymph node (LN) and gut-associated lymphoid tissue (GALT) biopsies from fully suppressed subjects, interrupted therapy, monitored plasma viral load (pVL), and repeated biopsies on 12 individuals as soon as pVL became detectable. Isolated HIV RNA-positive (vRNA+) cells were detected by in situ hybridization in LTs obtained before interruption in several patients. After interruption, multiple foci of vRNA+ cells were detected in 6 of 12 individuals as soon as pVL was measureable and in some subjects, in more than one anatomic site. Minimal estimates of the number of rebounding/founder (R/F) variants were determined by single-gene amplification and sequencing of viral RNA or DNA from peripheral blood mononuclear cells and plasma obtained at or just before viral recrudescence. Sequence analysis revealed a large number of R/F viruses representing recrudescent viremia from multiple sources. Together, these findings are consistent with the origins of recrudescent infection by reactivation from many latently infected cells at multiple sites. The inferred large pool of cells and sites to rekindle recrudescent infection highlights the challenges in eradicating HIV.

Abnormal Presence of Semimature Dendritic Cells That Induce Regulatory T Cells in HIV-Infected Subjects

Dendritic cells (DCs), because they orchestrate the immune response to microbes, represent an ideal target for pathogens attempting to evade the immune system. We hypothesized that interactions between human immunodeficiency virus (HIV) and DCs lead to the development of a semimature state, in which DCs migrate to lymph nodes but induce tolerance in T cells, rather than immunity. We found that lymph nodes from untreated HIV-infected subjects contained an abundance of semimature DCs, the disappearance of which correlated with the initiation of highly active antiretroviral therapy (HAART). Such lymph nodes also contained an abundance of T cells that had a regulatory phenotype and that persisted after HAART. Lymph node DCs from untreated HIV-infected subjects cultured with normal allogeneic T cells induced these T cells to adopt the phenotype of regulatory T cells, an ability that was lost after HAART. We conclude that HIV infection correlates with the presence of semimature DCs that stimulate T cell tolerance rather than immunity. These regulatory T cells may contribute to the lack of effective HIV immune responses.

Defining HIV and SIV Reservoirs in Lymphoid Tissues

A primary obstacle to an HIV-1 cure is long-lived viral reservoirs, which must be eliminated or greatly reduced. Cure strategies have largely focused on monitoring changes in T cell reservoirs in peripheral blood (PB), even though the lymphoid tissues (LT) are primary sites for viral persistence. To track and discriminate viral reservoirs within tissue compartments we developed a specific and sensitive next-generation in situ hybridization approach to detect vRNA, including vRNA+ cells and viral particles (“RNAscope”), vDNA+ cells (“DNAscope”) and combined vRNA and vDNA with immunohistochemistry to detect and phenotype active and latently infected cells in the same tissue section. RNAscope is highly sensitive with greater speed of analysis compared to traditional in situ hybridization. The highly sensitive and specific DNAscope detected SIV/HIV vDNA+ cells, including duplexed detection of vDNA and vRNA or immunophenotypic markers in the same section. Analysis of LT samples from macaques prior to and during combination antiretroviral therapy demonstrated that B cell follicles are an important anatomical compartment for both latent and active viral persistence during treatment. These new tools should allow new insights into viral reservoir biology and evaluation of cure strategies.

Protein kinase inhibitors of the quinazoline class exert anti-cytomegaloviral activity in vitro and in vivo

Cytomegalovirus infection is associated with severe disease in immunocompromised individuals. Current antiviral therapy faces several limitations. In a search of novel drug candidates, we describe here the anti-cytomegaloviral properties of two compounds of the chemical class of quinazolines, gefitinib (Iressa) and Ax7396 (RGB-315389). Both compounds showed strong inhibitory effects in vitro against human and animal cytomegaloviruses with IC(50)s in a low micromolar range. Cytotoxicity did not occur at these effective concentrations. The antiviral mode of action was based on the inhibition of protein kinase activity, mainly directed to a viral target kinase (UL97/M97) in addition to cellular target candidates. This was demonstrated by a high sensitivity of the respective protein kinases in vitro and by infection experiments with viral mutants carrying genomic alterations in the ORF UL97/M97 modulating viral drug sensitivity. In a guinea pig model, gefitinib showed inhibition of cytomegaloviral loads in blood and lung tissue. Importantly, the rate of mortality of infected animals was reduced by gefitinib treatment. In contrast to the in vitro data, Ax7396 showed no significant antiviral activity in a mouse model. Further in vivo analyses have to assess the potential use of gefitinib in the treatment of cytomegalovirus disease.

Antifibrotic Therapy in Simian Immunodeficiency Virus Infection Preserves CD4+ T-Cell Populations and Improves Immune Reconstitution With Antiretroviral Therapy

Even with prolonged antiretroviral therapy (ART), many human immunodeficiency virus-infected individuals have <500 CD4(+) T cells/µL, and CD4(+) T cells in lymphoid tissues remain severely depleted, due in part to fibrosis of the paracortical T-cell zone (TZ) that impairs homeostatic mechanisms required for T-cell survival. We therefore used antifibrotic therapy in simian immunodeficiency virus-infected rhesus macaques to determine whether decreased TZ fibrosis would improve reconstitution of peripheral and lymphoid CD4(+) T cells. Treatment with the antifibrotic drug pirfenidone preserved TZ architecture and was associated with significantly larger populations of CD4(+) T cells in peripheral blood and lymphoid tissues. Combining pirfenidone with an ART regimen was associated with greater preservation of CD4(+) T cells than ART alone and was also associated with higher pirfenidone concentrations. These data support a potential role for antifibrotic drug treatment as adjunctive therapy with ART to improve immune reconstitution.

Glycoprotein B (gB) vaccines adjuvanted with AS01 or AS02 protect female guinea pigs against cytomegalovirus (CMV) viremia and offspring mortality in a CMV-challenge model

The transmission of cytomegalovirus (CMV) from mother to fetus can give rise to severe neurodevelopment defects in newborns. One strategy to prevent these congenital defects is prophylactic vaccination in young women. A candidate vaccine antigen is glycoprotein B (gB). This antigen is abundant on the virion surface and is a major target of neutralization responses in human infections. Here, we have evaluated in a challenge model of congenital guinea pig CMV (GPCMV) infection, GPCMV-gB vaccines formulated with the clinically relevant Adjuvant Systems AS01B and AS02V, or with Freunds adjuvant (FA). Fifty-two GPCMV-seronegative female guinea pigs were administered three vaccine doses before being mated. GPCMV-challenge was performed at Day 45 of pregnancy (of an estimated 65 day gestation). Pup mortality rates in the gB/AS01B, gB/AS02V, and gB/FA groups were 24% (8/34), 10% (4/39) and 36% (12/33), respectively, and in the unvaccinated control group was 65% (37/57). Hence, efficacies against pup mortality were estimated at 64%, 84% and 44% for gB/AS01B (p<0.001), gB/AS02V (p<0.001) and gB/FA (p=0.014), respectively. Efficacies against GPCMV viremia (i.e. DNAemia, detected by PCR) were estimated at 88%, 68% and 25% for the same vaccines, respectively, but were only significant for gB/AS01B (p<0.001), and gB/AS02V (p=0.002). In dams with viremia, viral load was approximately 6-fold lower with vaccination than without. All vaccines were highly immunogenic after two and three doses. In light of these results and of other results of AS01-adjuvanted vaccines in clinical development, vaccine immunogenicity was further explored using human CMV-derived gB antigen adjuvanted with either AS01B or the related formulation AS01E. Both adjuvanted vaccines were highly immunogenic after two doses, in contrast to the lower immunogenicity of the unadjuvanted vaccine. In conclusion, the protective efficacy and immunogenicity of adjuvanted vaccines in this guinea pig model are supportive of investigating gB/AS01 and gB/AS02 in the clinic.

Impaired T-cell responses to sphingosine-1-phosphate in HIV-1 infected lymph nodes

The determinants of HIV-1-associated lymphadenopathy are poorly understood. We hypothesized that lymphocytes could be sequestered in the HIV-1+ lymph node (LN) through impairments in sphingosine-1-phosphate (S1P) responsiveness. To test this hypothesis, we developed novel assays for S1P-induced Akt phosphorylation and actin polymerization. In the HIV-1+ LN, naïve CD4 T cells and central memory CD4 and CD8 T cells had impaired Akt phosphorylation in response to S1P, whereas actin polymerization responses to S1P were impaired dramatically in all LN maturation subsets. These defects were improved with antiretroviral therapy. LN T cells expressing CD69 were unable to respond to S1P in either assay, yet impaired S1P responses were also seen in HIV-1+ LN T cells lacking CD69 expression. Microbial elements, HIV-1, and interferon α - putative drivers of HIV-1 associated immune activation all tended to increase CD69 expression and reduce T-cell responses to S1P in vitro. Impairment in T-cell egress from lymph nodes through decreased S1P responsiveness may contribute to HIV-1-associated LN enlargement and to immune dysregulation in a key organ of immune homeostasis.

Lymphoid Fibrosis Occurs in Long-Term Nonprogressors and Persists With Antiretroviral Therapy but May Be Reversible With Curative Interventions

Human immunodeficiency virus (HIV) replication causes lymphoid tissue (LT) fibrosis, which causes CD4(+) T-cell depletion. It is unknown whether people who spontaneously control HIV replication have LT fibrosis. We measured LT fibrosis and CD4(+) T cells in 25 HIV controllers, 10 noncontrollers, 45 HIV-positive individuals receiving therapy, and 10 HIV-negative individuals. Controllers had significant LT fibrosis and CD4(+) T-cell depletion, similar to noncontrollers, but the so-called Berlin patient (in whom HIV infection was cured) had near normal LT. Thus, LT fibrosis occurs in all HIV-infected subjects, and current therapy does not reverse it. Reversal of fibrosis during a curative intervention suggests that ongoing low-level virus production may maintain LT fibrosis.

Cyclic cidofovir (cHPMPC) prevents congenital cytomegalovirus infection in a guinea pig model

BackgroundCongenital cytomegalovirus (CMV) infection is a major public health problem. Antiviral therapies administered during pregnancy might prevent vertical CMV transmission and disease in newborns, but these agents have not been evaluated in clinical trials. The guinea pig model of congenital CMV infection was therefore used to test the hypothesis that antiviral therapy, using the agent agent cyclic cidofovir (cHPMPC), could prevent congenital CMV infection.ResultsPregnant outbred Hartley guinea pigs were challenged in the early-third trimester with guinea pig CMV (GPCMV) and treated with placebo, or the antiviral agent, cyclic cidofovir. To optimize detection of vertical infection, an enhanced green fluorescent protein (eGFP)-tagged virus was employed. Compared to placebo, cyclic cidofovir-treated dams and pups had reduced mortality following GPCMV challenge. The magnitude of GPCMV-induced maternal and fetal mortality in this study was reduced from 5/25 animals in the placebo group to 0/21 animals in the treatment group (p = 0.05, Fishers exact test). By viral culture assay, antiviral therapy was found to completely prevent GPCMV transmission to the fetus. In control pups, 5/19 (26%) were culture-positive for GPCMV, compared to 0/16 of pups in the cyclic cidofovir treatment group (p < 0.05, Fishers exact test).ConclusionAntiviral therapy with cyclic cidofovir improves pregnancy outcomes in guinea pigs, and eliminates congenital CMV infection, following viral challenge in the third trimester. This study also demonstrated that an eGFP-tagged recombinant virus, with the reporter gene inserted into a dispensable region of the viral genome, retained virulence, including the potential for congenital transmission, facilitating tissue culture-based detection of congenital infection. These observations provide support for clinical trials of antivirals for reduction of congenital CMV infection.