Study DesignA randomized, double-blind, placebo controlled phase I trial.MethodsThe trial was conducted in 32 HIV-uninfected healthy volunteers to assess the safety and immunogenicity of prime-boost vaccination regimens with either 2 doses of ADVAX, a DNA vaccine containing Chinese HIV-1 subtype C env gp160, gag, pol and nef/tat genes, as a prime and 2 doses of TBC-M4, a recombinant MVA encoding Indian HIV-1 subtype C env gp160, gag, RT, rev, tat, and nef genes, as a boost in Group A or 3 doses of TBC-M4 alone in Group B participants. Out of 16 participants in each group, 12 received vaccine candidates and 4 received placebos.ResultsBoth vaccine regimens were found to be generally safe and well tolerated. The breadth of anti-HIV binding antibodies and the titres of anti-HIV neutralizing antibodies were significantly higher (p<0.05) in Group B volunteers at 14 days post last vaccination. Neutralizing antibodies were detected mainly against Tier-1 subtype B and C viruses. HIV-specific IFN-γ ELISPOT responses were directed mostly to Env and Gag proteins. Although the IFN-γ ELISPOT responses were infrequent after ADVAX vaccinations, the response rate was significantly higher in group A after 1st and 2nd MVA doses as compared to the responses in group B volunteers. However, the priming effect was short lasting leading to no difference in the frequency, breadth and magnitude of IFN-γELISPOT responses between the groups at 3, 6 and 9 months post-last vaccination.ConclusionsAlthough DNA priming resulted in enhancement of immune responses after 1st MVA boosting, the overall DNA prime MVA boost was not found to be immunologically superior to homologous MVA boosting.Trial RegistrationClinical Trial Registry CTRI/2009/091/000051

ACE2 is a receptor of entry of SARS-CoV-2 into the host cells, and its upregulation has been implicated in increasing susceptibility of individuals to this infection. The clinical picture of COVID-19 suggests a role of ACE2 blockade, rather than its overexpression, in causing the pathogenesis. ACE2 blockade results in increased angiotensin II activity with simultaneous hampering of functions of angiotensin-(1-7)/MasR axis. Acute respiratory distress due to interstitial pulmonary fibrosis, cardiomyopathy and shock reported in COVID-19 patients can be explained by imbalanced angiotensin II and angiotensin-(1-7) activities. Failure of angiotensin II type 1 receptor blockers to control the severity of SARS-CoV-2 infections indicates the importance of simultaneous induction of angiotensin-(1-7)/MasR axis for correcting pathological conditions in COVID-19 through its anti-fibrotic, anti-inflammatory, vasodilatory, and cardioprotective roles. MasR agonists have also shown organ protective effects in a number of animal studies. Unfortunately, these agonists have not been tested in clinical studies. Their evaluation in seriously ill COVID-19 patients is urgently warranted to reduce mortality due to infection.

HIV-specific antibody-dependent cell cytotoxicity (ADCC) is likely to be important in governing protection from human immunodeficiency virus (HIV) and slowing disease progression. Little is known about the ADCC responses to HIV-1 subtype C. We characterized ADCC responses in HIV-1 subtype C-infected Indian subjects with slow disease progression and identified the dominant antigenic regions recognized by these antibodies. ADCC responses were measured in plasma from 34 long-term non-progressors (LTNPs), who were asymptomatic and maintained CD4 count above 500 cells/mm3 for the last 7 years in the absence of antiretroviral therapy (ART), and 58 ART naïve progressors with CD4 count <500 cells/mm3 against overlapping HIV-1 peptides using a flow cytometry-based antibody-dependent natural killer (NK) cell activation assay. The assay measured CD107a expression on NK cells as a marker of antibody-dependent NK cell activation and IFN-γ secretion by NK cells upon activation. The ADCC epitopes were mapped using the matrix of overlapping peptides. Indian LTNPs showed higher and broader ADCC responses compared to the progressors. The Env-C and Tat-specific ADCC responses were associated with lower plasma viral load, whereas the Env-C responses were also associated with higher CD4 counts. Five of 10 LTNP responders targeted epitopes in the V3 region (amino acids 288–330) of Env-C. Additionally, three Tat regions were targeted by ADCC antibodies from LTNPs. ADCC responses were associated with slow HIV progression in Indian subtype C-infected cohort. The frequently recognized peptides from the V3 loop of Env and the novel epitopes from Tat by the LTNPs warrants further study to understand the role of ADCC responses to these regions in control and prevention of HIV-1 infection.

Therapeutic vaccinations using human immunodeficiency virus (HIV) antigens in HIV-infected patients on antiretroviral therapy (ART) have so far been attempted with the purpose of inducing CTL response. However, they can also be useful as a strategy for activation of latent HIV reservoir, which is thought to be mainly comprised of latently infected HIV-specific memory CD4 cells, eventually leading to elimination of the virus. The present study was carried out to explore the ability of different HIV antigens to activate HIV replication as assessed by intracellular P24 detection as well as to induce T cell responses in terms of cytokine expression by flow cytometry after stimulation of PBMCs from HIV-infected patients. HIV antigens were found to be able to activate most of the CD4 T cells harboring proviral DNA. HIV-1 Pol and Env were responsible for induction of higher HIV replication in terms of both magnitude and frequency followed by Gag and Nef. As opposed to this, Pol and Env contributed to fewer numbers of polyfunctional CD8 cells desirable for elimination of HIV-infected cells in comparison to Gag and Nef. Thus, HIV antigens may provide a strategy for the activation of a latent reservoir. It was observed that HIV replication started as early as half an hour after in vitro activation indicating a stringent need for maintaining effective concentrations of antiretroviral drugs to prevent further spread of HIV during this process. HIV-infected cells were found to be responsible for higher IL-10 secretion after activation, which could also serve as one of the reasons for suppressed CD8 responses to Pol and Env as more HIV-infected CD4 cells would be secreting IL-10 in response to these antigens. Since IL-10 blockade helped to improve immune responses in terms of cytokine secretion, it should be considered in settings of therapeutic vaccination to improve CTL responses, which will ultimately limit the persistence of the viral reservoir.

Circulating full-length osteopontin (FL-OPN) is elevated in plasma from patients with various infectious diseases, such as adult T-cell leukemia, Mycobacterium tuberculosis (TB), hepatitis virus infection, leptospirosis, acquired immune deficiency syndrome (AIDS), AIDS/TB, and coronavirus disease 2019 (COVID-19). Proteolysis of OPN by thrombin, matrix metalloproteases, caspase 8/3, cathepsin D, plasmin, and enterokinase generates various cleaved OPNs with a variety of bioactivities by binding to different target cells. Moreover, OPN is susceptible to gradual proteolysis. During inflammation, one of the cleaved fragments, N-terminal thrombin-cleaved OPN (trOPN or OPN-Arg168 [OPN-R]), induces dendritic cell (DC) adhesion. Further cleavage by carboxypeptidase B2 or carboxypeptidase N removes Arg168 from OPN-R to OPN-Leu167 (OPN-L). Consequently, OPN-L decreases DC adhesion. In particular, the differences in plasma level over time are observed between FL-OPN and its cleaved OPNs during inflammation. We found that the undefined OPN levels (mixture of FL-OPN and cleaved OPN) were elevated in plasma and reflected the pathology of TB and COVID-19 rather than FL-OPN. These infections are associated with elevated levels of various proteases. Inhibition of the cleavage or the activities of cleaved products may improve the outcome of the therapy. Research on the metabolism of OPN is expected to create new therapies against infectious diseases.

Background: Immunological non-responders (INR) represent a unique category of HIV-infected patients on antiretroviral therapy. These patients have suppressed viremia but a suboptimal increase in CD4 cell count, which might have opposing effects on functional immune reconstitution. Hence, the extent of immune reconstitution in INR patients was investigated in order to determine their susceptibility to opportunistic infections. Methods: Twenty-three INR patients (CD4 increase <50 cells/mm 3 , viral load <40 copies/ml), 40 age-, sex-, and baseline CD4 count-matched responders (CD4 increase >100 cells/mm 3 , viral load <40 copies/ml), and 18 treatment failures defined as per the national guidelines were enrolled at 1 year of antiretroviral therapy. The following examinations were performed: haemogram, phenotypic characterization by flow cytometry, and assessment of functional immune status by ELISPOT and intracellular cytokine assays. Results: A higher percentage of INR patients had clinically symptomatic infections than the responders. CD8 + activation and innate immune parameters, including the absolute neutrophil count and natural killer (NK) cell frequency and functionality, were restored in the INR patients. They had significantly higher non-HIV antigen-specific T-cell responses and activated CD4 + cells, but significantly compromised T-cell functionality, as assessed after anti-CD3 stimulation, and lower CD31 + and CD62L + CD4 + cells. Conclusions: INR patients showed lower thymic output, incomplete functional T-cell reconstitution, higher responses to HIV co-pathogens, and higher symptomatic events, indicating the need for close monitoring and intervention strategies to overcome their continuing immunocompromised status.

Background: Early detection of viremia in HIV infected patients on anti-retroviral therapy (ART) is important to prevent disease progression as well as accumulation of drug resistance mutations. This makes HIV viral load (VL) monitoring indispensable in HIV infected patients on ART. However VL, being an expensive test, results in heavy financial burden on health services. Hence, cheaper surrogate markers of viremia are desired to reduce overall cost of management of HIV infected patients. Methods: We enrolled aviremic (n = 63, M:F = 31:32) and viremic (n = 43, M:F = 21:22) HIV infected patients at 1 year after ART initiation. Viremic individuals were identified as those having a plasma VL of more than 1000 copies/µl and aviremic individuals as less than 40 copies/µl. The study participants also included immuno-virologically discordant patients as they demonstrate differential degrees of immune-reconstitution and are likely to harbour concomitant infections influencing levels of immune-activation markers screened as the surrogate markers. Immune activation markers viz. plasma hs-CRP, soluble-CD14 and Galectin-9 levels were estimated by ELISA, IL-6 by luminex assay and percentages of CD38+ CD8+ cells were determined by flow cytometry. The levels were compared between viremic and aviremic patients and correlated with plasma viral load. Receiver operated curve (ROC) analysis was done for plasma Galectin-9 levels. Results: Viremic patients had significantly higher levels of Galectin-9 and %CD38+ CD8+ cells (p values < 0.0001) than aviremic patients. Levels of the other activation markers did not differ between viremic and aviremic individuals. Galectin-9 levels (r = 0.76) and %CD38+ CD8+ cells (r = 0.39) correlated positively with VL. Area under curve for Galectin-9 levels for distinguishing between viremic and aviremic individuals was 0.98. Youden index, sensitivity, specificity, positive predictive value and negative predictive value for Galectin-9 levels were 0.87, 0.97, 0.90, 0.87 and 0.98, respectively, at the cutoff value of 5.79 ng/ml. Conclusions: Plasma Galectin-9 levels could identify viremic individuals with sensitivity and specificity of more than 90%. Thus, they showed a potential to serve as a surrogate marker of viremia in HIV infected patients on ART and

Galectin-9 (Gal-9) and osteopontin (OPN) play immunomodulatory roles in tuberculosis and HIV infections. Evaluation of their levels as well as their interplay with different pro-inflammatory cytokines is critical to understand their role in immunopathogenesis of HIV/tuberculosis co-infection considering the complexity of the disease. Plasma levels of these proteins were measured by ELISAs in HIV-negative individuals with pulmonary (n = 21), extrapulmonary (n = 33), and latent tuberculosis (n = 22) and in HIV infected patients with pulmonary (n = 14), latent tuberculosis (n = 17), and without tuberculosis (n = 41). Levels of pro-inflammatory cytokines were estimated by Luminex assay. Receiver operated characteristic curve analysis was performed to evaluate discriminatory roles of these proteins. Spearman's correlation analysis was performed with the markers of HIV and tuberculosis disease progression to evaluate their immunopathogenic roles. Gal-9 and OPN levels were higher in HIV uninfected patients with active tuberculosis than with latent tuberculosis. Gal-9 but not OPN levels were higher in HIV infected patients with active tuberculosis than with latent tuberculosis. Area under curve for Galectin-9 was >0.9 in HIV/tuberculosis coinfection and extrapulmonary tuberculosis. OPN and IL-6 levels were higher in patients with severe chest X-ray grade indicating its association with severity of the disease and positively correlated with each other. Stronger positive and negative correlations of Gal-9 levels, respectively, with viral loads and CD4 cell counts in HIV infected patients were observed than OPN levels indicating their association with HIV disease progression. Thus, significantly elevated Gal-9 levels were reported for the first time in HIV/tuberculosis co-infection and extrapulmonary tuberculosis in our study than single infections with HIV and tuberculosis. The study indicated a need for further evaluation of monitoring role of Gal-9 for detection of developing tuberculosis in HIV infected individuals. The findings also indicated differential roles of Gal-9 and OPN in the pathogenesis of tuberculosis and HIV infections.