No evidence that circulating HIV-specific immune responses contribute to persistent inflammation and immune activation in persons on long-term ART

OBJECTIVE

People with HIV (PWH) have persistently elevated levels of inflammation and immune activation despite suppressive antiretroviral therapy (ART), with specific biomarkers showing associations with non-AIDS-defining morbidities and mortality. We investigated the potential role of the HIV-specific adaptive immune response, which also persists under ART, in driving levels of these clinically relevant biomarkers.

DESIGN

Cohort-based study.

METHODS

HIV-specific IFN-γ-producing T-cell responses and antibody concentrations were measured in blood at study entry in the ACTG A5321 cohort, following a median of 7 years of suppressive ART. HIV persistence measures including cell-associated (CA)-DNA, CA-RNA, and plasma HIV RNA (single-copy assay) were also assessed at study entry. Plasma inflammatory biomarkers and T-cell activation and cycling were measured at a pre-ART time point and at study entry.

RESULTS

Neither the magnitudes of HIV-specific T-cell responses nor HIV antibody levels were correlated with levels of the inflammatory or immune activation biomarkers, including hs-CRP, IL-6, neopterin, sCD14, sCD163, TNF-α, %CD38 + HLA-DR + CD8 + and CD4 + cells, and %Ki67 + CD8 + and CD4 + cells - including after adjustment for pre-ART biomarker level. Plasma HIV RNA levels were modestly correlated with CD8 + T-cell activation ( r  = 0.25, P  = 0.027), but other HIV persistence parameters were not associated with these biomarkers. In mediation analysis, relationships between HIV persistence parameters and inflammatory biomarkers were not influenced by either HIV-specific T-cell responses or antibody levels.

CONCLUSION

Adaptive HIV-specific immune responses do not appear to contribute to the elevated inflammatory and immune activation profile in persons on long-term ART.

SARS CoV-2 mRNA vaccination exposes latent HIV to Nef-specific CD8+ T-cells

Efforts to cure HIV have focused on reactivating latent proviruses to enable elimination by CD8+ cytotoxic T-cells. Clinical studies of latency reversing agents (LRA) in antiretroviral therapy (ART)-treated individuals have shown increases in HIV transcription, but without reductions in virologic measures, or evidence that HIV-specific CD8+ T-cells were productively engaged. Here, we show that the SARS-CoV-2 mRNA vaccine BNT162b2 activates the RIG-I/TLR - TNF - NFκb axis, resulting in transcription of HIV proviruses with minimal perturbations of T-cell activation and host transcription. T-cells specific for the early gene-product HIV-Nef uniquely increased in frequency and acquired effector function (granzyme-B) in ART-treated individuals following SARS-CoV-2 mRNA vaccination. These parameters of CD8+ T-cell induction correlated with significant decreases in cell-associated HIV mRNA, suggesting killing or suppression of cells transcribing HIV. Thus, we report the observation of an intervention-induced reduction in a measure of HIV persistence, accompanied by precise immune correlates, in ART-suppressed individuals. However, we did not observe significant depletions of intact proviruses, underscoring challenges to achieving (or measuring) HIV reservoir reductions. Overall, our results support prioritizing the measurement of granzyme-B-producing Nef-specific responses in latency reversal studies and add impetus to developing HIV-targeted mRNA therapeutic vaccines that leverage built-in LRA activity.

Inhibition of major histocompatibility complex-I antigen presentation by sarbecovirus ORF7a proteins

Viruses employ a variety of strategies to escape or counteract immune responses, including depletion of cell surface major histocompatibility complex class I (MHC-I), that would ordinarily present viral peptides to CD8+ cytotoxic T cells. As part of a screen to elucidate biological activities associated with individual SARS-CoV-2 viral proteins, we found that ORF7a reduced cell surface MHC-I levels by approximately 5-fold. Nevertheless, in cells infected with SARS-CoV-2, surface MHC-I levels were reduced even in the absence of ORF7a, suggesting additional mechanisms of MHC-I downregulation. ORF7a proteins from a sample of sarbecoviruses varied in their ability to induce MHC-I downregulation and, unlike SARS-CoV-2, the ORF7a protein from SARS-CoV lacked MHC-I downregulating activity. A single-amino acid at position 59 (T/F) that is variable among sarbecovirus ORF7a proteins governed the difference in MHC-I downregulating activity. SARS-CoV-2 ORF7a physically associated with the MHC-I heavy chain and inhibited the presentation of expressed antigen to CD8+ T-cells. Speficially, ORF7a prevented the assembly of the MHC-I peptide loading complex and causing retention of MHC-I in the endoplasmic reticulum. The differential ability of ORF7a proteins to function in this way might affect sarbecovirus dissemination and persistence in human populations, particularly those with infection- or vaccine-elicited immunity.

A participant-derived xenograft model of HIV enables long-term evaluation of autologous immunotherapies

HIV-specific CD8⁺ T cells partially control viral replication and delay disease progression, but they rarely provide lasting protection, largely due to immune escape. Here, we show that engrafting mice with memory CD4⁺ T cells from HIV⁺ donors uniquely allows for the in vivo evaluation of autologous T cell responses while avoiding graft-versus-host disease and the need for human fetal tissues that limit other models. Treating HIV-infected mice with clinically relevant HIV-specific T cell products resulted in substantial reductions in viremia. In vivo activity was significantly enhanced when T cells were engineered with surface-conjugated nanogels carrying an IL-15 superagonist, but it was ultimately limited by the pervasive selection of a diverse array of escape mutations, recapitulating patterns seen in humans. By applying mathematical modeling, we show that the kinetics of the CD8⁺ T cell response have a profound impact on the emergence and persistence of escape mutations. This “participant-derived xenograft” model of HIV provides a powerful tool for studying HIV-specific immunological responses and facilitating the development of effective cell-based therapies.

HIV-specific T cell responses reflect substantive in vivo interactions with antigen despite long-term therapy

Antiretroviral therapies (ARTs) abrogate HIV replication; however, infection persists as long-lived reservoirs of infected cells with integrated proviruses, which reseed replication if ART is interrupted. A central tenet of our current understanding of this persistence is that infected cells are shielded from immune recognition and elimination through a lack of antigen expression from proviruses. Efforts to cure HIV infection have therefore focused on reactivating latent proviruses to enable immune-mediated clearance, but these have yet to succeed in reducing viral reservoirs. Here, we revisited the question of whether HIV reservoirs are predominately immunologically silent from a new angle: by querying the dynamics of HIV-specific T cell responses over long-term ART for evidence of ongoing recognition of HIV-infected cells. In longitudinal assessments, we show that the rates of change in persisting HIV Nef-specific responses, but not responses to other HIV gene products, were associated with residual frequencies of infected cells. These Nef-specific responses were highly stable over time and disproportionately exhibited a cytotoxic, effector functional profile, indicative of recent in vivo recognition of HIV antigens. These results indicate substantial visibility of the HIV-infected cells to T cells on stable ART, presenting both opportunities and challenges for the development of therapeutic approaches to curing infection.

SARS-CoV-2-specific T cells are rapidly expanded for therapeutic use and target conserved regions of the membrane protein

T-cell responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been described in recovered patients, and may be important for immunity following infection and vaccination as well as for the development of an adoptive immunotherapy for the treatment of immunocompromised individuals. In this report, we demonstrate that SARS-CoV-2-specific T cells can be expanded from convalescent donors and recognize immunodominant viral epitopes in conserved regions of membrane, spike, and nucleocapsid. Following in vitro expansion using a good manufacturing practice-compliant methodology (designed to allow the rapid translation of this novel SARS-CoV-2 T-cell therapy to the clinic), membrane, spike, and nucleocapsid peptides elicited interferon-γ production, in 27 (59%), 12 (26%), and 10 (22%) convalescent donors (respectively), as well as in 2 of 15 unexposed controls. We identified multiple polyfunctional CD4-restricted T-cell epitopes within a highly conserved region of membrane protein, which induced polyfunctional T-cell responses, which may be critical for the development of effective vaccine and T-cell therapies. Hence, our study shows that SARS-CoV-2 directed T-cell immunotherapy targeting structural proteins, most importantly membrane protein, should be feasible for the prevention or early treatment of SARS-CoV-2 infection in immunocompromised patients with blood disorders or after bone marrow transplantation to achieve antiviral control while mitigating uncontrolled inflammation.

Insertion of a casein kinase recognition sequence induces phosphorylation of ovine beta-lactoglobulin in transgenic mice

We have shown that the cellular mechanisms of the mammary gland can be used to produce a phosphorylated form of a normally unphosphorylated milk protein. This was achieved by the insertion of a beta-casein DNA sequence coding for a group of mammary gland casein kinase recognition sites into ovine beta-lactoglobulin. Transgenic mice carrying this modified gene were generated and lactating females were shown to produce a novel beta-lactoglobulin in their milk. The infrared spectrum, reactivity to antiphosphoserine antibody and reduction of electrophoretic mobility on treatment with alkaline phosphatase showed that the novel protein recovered from the milk whey (serum) was phosphorylated and molecular mass determination by mass spectrometry was consistent with the phosphorylation of one or two residues. A similar level of phosphorylation was measured by quantitative infrared spectroscopy. Centrifugation of the milk to pellet the casein micelles showed that most of the phosphorylated beta-lactoglobulin was in the whey and hence not incorporated into casein micelles.

HIV positive tests at Coronial Services in Victoria 1989-1996: lessons for HIV surveillance

Results of routine testing at other sites can supplement surveillance of the HIV epidemic in Australia which is largely based upon voluntary testing. Since 1989, systematic onsite HIV testing has been undertaken on all bodies taken to the Victorian Institute of Forensic Medicine (VIFM). Information was collected on all cases of HIV infection detected at VIFM between 1989 and 1996, and matched to surveillance databases. In 8 years, 75 people were diagnosed with HIV; all except one were male. The age range was 14-70 years, mean 37.4 years. The major causes of death were suicide 35%, AIDS 21%, drug toxicity 16%, natural causes 12% and injury 7%. The major exposure categories were male homosexual 51%, male bisexual 11%, homosexual/bisexual IDU 16%, IDU other 8%, and haemophiliac 7%. For only two was exposure information unavailable. Seropositivity for anti-HCV and HBsAg was 37% and 11% respectively. The deceased was recorded as having HIV/AIDS on the police report in 73% of cases, and at least 90% of subjects had been diagnosed with HIV prior to their death. The study suggests there is relatively little undiagnosed HIV infection in Victoria, that HIV infection has not moved outside traditional risk groups, and that many tests for HIV are undertaken using false namecodes. Many patients could not be matched on the HIV/AIDS databases, identifying a problem with HIV surveillance systems in Victoria, and the need to capture all information on HIV positives detected at VIFM.

The epidemiology of notified genital Chlamydia trachomatis infection in Victoria, Australia: a survey of diagnosing providers

Data on 259 notified cases of genital chlamydia infection diagnosed in Victoria Australia in January and February 1995 were augmented by call-back. Risk factor data was available for 221. Patients were primarily adolescents or young adults (median age 23 years); 66% were women. Men were more commonly symptomatic. Persons without symptoms were tested as a result of partner notification, sexual risk, termination of pregnancy, or because of abnormalities on genital examination. Limitations of antigen-based screening tests in low prevalence populations were rarely considered. Although antimicrobial treatment usually accorded with available guidelines, case management was not well geared to reducing the broader issue of risk of this infection in the community. Data management systems for handling name-coded data, and systems for recall and follow-up of diagnosed patients and their partners were often inadequate. Sexual history taking had not generally identified details of sexual partners. Partner notification was generally regarded as the patient's responsibility and professional help with contact tracing was rarely sought. Control of chlamydia will require much greater attention to management issues, particularly contact tracing.

Cryptosporidiosis in patients with AIDS

Cases of cryptosporidiosis in patients with the acquired immunodeficiency syndrome (AIDS) residing in Melbourne over a 6-year period (1990-1995) are described. During this period 85 cases occurred, while 979 new AIDS diagnoses were notified. Over this period temporal clustering in cryptosporidial detection was evident (P=0.007), but the pattern was not statistically associated with the season, rainfall (P=0.88), mean average maximal temperature (P=0.15) or mean average minimal temperature. Further studies should identify these risk factors and provide an opportunity to prevent this devastating disease.

Bovine beta-casein expressed in transgenic mouse milk is phosphorylated and incorporated into micelles

Transgenic mice carrying the bovine beta-casein gene linked to the promoter sequence of the sheep beta-lactoglobulin milk protein gene were produced. Four of seven lines expressed the transgene protein with mice from the two highest expressing lines producing 4 to 5 mg ml(-1) of this protein in their milk. The foreign protein was associated with the casein micelles and did not segregate into the whey fraction on centrifugation of milk samples. Following purification, the protein was characterized by amino acid analysis, gel electrophoresis, capillary zone electrophoresis, and trypsinolysis. The results showed that the transgene protein was authentic, phosphorylated bovine beta-casein A(1).

A profile of HIV testing in Victoria to the end of 1993. Victorian Collaborative Group on HIV and AIDS Surveillance (VCGHAS)

Examination of testing patterns for human immunodeficiency virus (HIV) in a population is important because it affects interpretation of surveillance data on new HIV diagnoses and can guide the targeting and evaluation of campaigns to encourage appropriate antibody testing. This report describes a relatively inexpensive mechanism of collecting information on who is being tested for HIV in Victoria (other than at the Blood Bank). The annual number of HIV tests performed in Victoria increased steadily throughout the 1980s but the rate of increase slowed in the early 1990s. By 1993, women accounted for almost half of HIV tests, although they made up only 8 per cent of positive tests. There were marked differences in the volume of testing and testing profiles of different laboratories. The information available on personal risk category and the reasons for HIV tests show that many people of low risk are tested, although conclusions are limited by inadequate information elicited or provided by many requesting doctors. For better information on what is occurring with respect to HIV testing, the fundamental requirement is better compliance from requesting doctors in supplying basic information on who they test and why.

Ascertaining exposure categories of HIV-infected individuals with previously unrecorded risk data

OBJECTIVES

To improve the quality of surveillance data for HIV in Victoria by following up all cases with an unknown exposure category; and to determine whether those with no exposure category included cases of transmission other than via the conventionally recognised routes.

METHODS

The Victorian HIV database records data on all people diagnosed with HIV in Victoria, including information on route of exposure to the virus. We identified all HIV diagnoses to which no exposure category had been attributed and, with the permission of the State Minister for Health, obtained access to namecoded testing records. Exposure categories, where possible, were obtained directly from these records. Otherwise, cases were checked against the namecoded AIDS database and, if necessary, an intensive process of call-back to laboratories, diagnosing doctors and HIV treatment centres was undertaken.

RESULTS

The database initially contained records for 289 people with unknown exposure categories (9.1% of Victorian people with HIV infection). We identified exposure categories for 155 of these people.

CONCLUSIONS

Exposure categories for those cases previously without data were similar to those for cases where exposure category was known. No instances of HIV transmission by previously unrecognised means were detected.