Clinical characteristics and prognosis of Talaromycosis marneffei associated immune reconstitution inflammatory syndrome in AIDS patients.

BACKGROUND: Immune reconstitution inflammatory syndrome (IRIS) is an inflammatory reaction that occurs in HIV/AIDS patients after antiretroviral therapy (ART) initiation. Along with immune system recovery, IRIS can overreact to existing infections or latent pathogens, causing symptoms that mimic those infections. Few studies elucidated the clinical features and prognosis of Talaromycosis marneffei (TSM)-associated IRIS in HIV/AIDS patients. The aim of our study was to evaluate the incidence, clinical characteristics, and prognosis of TSM-associated IRIS by retrospectively analyzing the clinical data of HIV/AIDS patients with TSM. METHODOLOGY/PRINCIPAL FINDINGS: A total of 224 HIV/AIDS inpatients with TSM were enrolled, aged between 19 and 81 years. Among them, 86.6% were male and 13.4% were female, of which 24 (10.7%) patients developed IRIS. In IRIS group, the median time from ART initiation to IRIS occurrence was 9.0 days (IQR, 5.0-16.8 days), with 87.5% (21/24) occurring within 2 weeks. Primary clinical manifestations included recurrent fever and exacerbation of pulmonary infection. At the onset of IRIS, 54.2% (13/24) patients were treated with intravenous dexamethasone, and 12.5% (5/24) patients were treated with oral prednisone for 1-3 weeks. No significant differences in baseline characteristics or ART regimens were observed between IRIS and non-IRIS groups; however, patients in IRIS group had higher levels of CRP, CD4+ count, and CD4+/CD8+ ratio than non-IRIS group (equivalent time point: 1-2 weeks after ART initiation) at IRIS onset. The IRIS group exhibited longer hospital stays and higher readmission rates, but equivalent mortality rates compared with non-IRIS group. CONCLUSIONS/SIGNIFICANCE: IRIS is a common complication in HIV/AIDS patients with TSM, often occurring within 2 weeks after ART initiation and exhibiting more pronounced immune reconstitution. The occurrence of IRIS significantly extended the hospitalization duration and increased the rate of readmission but had no influence on the mortality rate.

Pretreatment drug resistance among people living with HIV from 2018 to 2022 in Guangzhou, China.

The presence of pretreatment drug resistance (PDR) is posing an increasing threat to HIV control. Here we investigated drug resistance mutations (DRMs) and PDR among 6831 HIV-infected individuals from 2018 to 2022 in Guangzhou, China. DRMs were detected among 24.5% of the patients. The overall prevalence of PDR was 7.4%, with resistance rate to nucleotide reverse transcriptase inhibitor (NRTI) being 1.3%, nonnucleoside reverse transcriptase inhibitor (NNRTI) 4.8%, and protease inhibitor (PI) 1.4%. Abacavir (0.8%) resistance was the most common in NRTI, followed by resistance to emtricitabine (0.6%), lamivudine (0.6%), and tenofovir disoproxil fumarate (0.3%). In NNRTI, nevirapine (3.7%) resistance was the most common, followed by efavirenz (3.5%) and rilpivirine (3.4%). Among PI, resistance to tipranavir (0.8%), nelfinavir (0.6%), fosamprenavir (0.2%) and lopinavir (0.1%) was most frequent. Annual prevalence of PDR showed an increase trend from 2018 to 2022, although not significant. In the multivariable logistic regression model, hepatitis B surface antigen positivity, circulating recombinant form (CRF) 55_01B, CRF08_BC, CRF59_01B, and subtype B were demonstrated as associated risk factors for PDR. The overall prevalence of PDR in Guangzhou was moderate, with relatively severe NNRTI resistance. Therefore, it remains crucial to continue monitoring PDR among newly diagnosed HIV-infected individuals.

An evaluation of Mp1p antigen screening for talaromycosis in HIV-infected antiretroviral therapy-naïve population in Guangdong, China.

BACKGROUND: Talaromycosis is one of the most common opportunistic infections in human immunodeficiency virus (HIV) infected patients. However, few researches have explored the prevalence in Southern China and fully assessed the value of the Mp1p antigen screening for the diagnosis of talaromycosis. METHODOLOGY/PRINCIPAL FINDINGS: We performed a cross-sectional study of HIV-infected antiretroviral therapy (ART)-naïve adult patients who were seen in 2018 at Guangzhou Eighth People's Hospital, Guangzhou Medical University. Serum samples collected from all the 784 enrolled patients were tested for Mp1p antigen using double-antibody sandwich enzyme-linked immunosorbent assay. A culture of pathogen was conducted in 350 clinically suspected patients to confirm talaromycosis. The overall prevalence of talaromycosis based on the Mp1p antigen detection was 11.4% (89/784) and peaked at 32.2% (75/233) in patients with CD4+ ≤50 Nr/µl. Logistic regression analysis found Mp1p antigen positive rate decreased with the increase in CD4+ counts (OR 0.982, 95% CI 0.977-0.987, P<0.01). The optimal cut-off point of the CD4+ count was 50 Nr/µl or less. Among the 350 patients received both fungal culture and Mp1p antigen detection, 95/350 (27.1%) patients were culture-positive for a Talaromyces marneffei, 75/350 (21.4%) patients were Mp1p antigen positive. The Mp1p antigen assay showed a good agreement to the culture of pathogen, and the sensitivity, specificity, positive predictive value, negative predictive value and kappa value was 71.6% (68/95), 97.3% (248/255), 90.7% (68/75), 90.2% (248/275), and 0.737, respectively. The screening accuracy of the Mp1p antigen assay in patients with CD4+ counts of ≤50 Nr/µl was superior to that in those with higher CD4+ counts. CONCLUSIONS/SIGNIFICANCE: Mp1p antigen screening can be an effective tool for more efficient diagnosis of Talaromycosis, especially in HIV/AIDS patients with low CD4+ counts. Future validation studies are needed.

Incidence and factors associated with hepatitis B surface antigen seroclearance in patients co-infected with HBV/HIV during antiretroviral therapy in Guangdong, China.

BACKGROUND: Hepatitis B surface antigen (HBsAg) clearance is vital for a functional cure of hepatitis B virus (HBV) infection. However, the incidence and predictors of HBsAg seroclearance in patients co-infected with HBV and human immunodeficiency virus (HIV) remain largely unknown in Guangdong, China. METHODS: Between 2009 and 2019, patients co-infected with HBV/HIV undergoing antiretroviral therapy (ART) in Guangzhou Eighth People's Hospital affiliated to Guangzhou Medical University were retrospectively reviewed with the endpoint on December 31, 2020. The incidence and risk factors for HBsAg seroclearance were evaluated using Kaplan-Meier and multivariate Cox regression analyses. RESULTS: A total of 1550 HBV/HIV co-infected patients were included in the study, with the median age of 42 years and 86.0% (1333/1550) males. Further, 98.3% (1524/1550) received ART containing tenofovir disoproxil fumarate (TDF) plus lamivudine (3TC). HBV DNA was examined in 1283 cases at the last follow-up. Over the median 4.7 years of follow-up, 8.1% (126/1550) patients achieved HBsAg seroclearance, among whom 50.8% (64/126) obtained hepatitis B surface antibody, 28.1% (137/488) acquired hepatitis B e antigen seroconversion, and 95.9% (1231/1283) undetectable HBV DNA. Compared with patients who maintained HBsAg positive, cases achieving HBsAg seroclearance showed no differences in age, gender, CD4 + T cell count, alanine aminotransferase (ALT) level, or fibrosis status; however, they presented lower HBV DNA levels, lower HBsAg levels, and higher rates of HBV genotype B at the baseline. Multivariate analysis showed that baseline HBsAg <1500 cutoff index (COI) (adjusted hazard ratio [aHR], 2.74, 95% confidence interval [95% CI]: 1.48-5.09), ALT elevation >2 × upper limit of normal during the first six months after receiving ART (aHR, 2.96, 95% CI: 1.53-5.77), and HBV genotype B (aHR, 3.73, 95% CI: 1.46-9.59) were independent predictors for HBsAg seroclearance (all P <0.01). CONCLUSIONS: Long-term TDF-containing ART has high anti-HBV efficacy including relatively high overall HBsAg seroclearance in HBV/HIV co-infected patients. Lower baseline HBsAg levels, HBV genotype B, and elevated ALT levels during the first six months of ART are potential predictors of HBsAg seroclearance.

Early on-treatment plasma interleukin-18 as a promising indicator for long-term virological response in patients with HIV-1 infection.

Background and aims: It is necessary to identify simple biomarkers that can efficiently predict the efficacy of long-term antiretroviral therapy (ART) against human immunodeficiency virus (HIV), especially in underdeveloped countries. We characterized the dynamic changes in plasma interleukin-18 (IL-18) and assessed its performance as a predictor of long-term virological response. Methods: This was a retrospective cohort study of HIV-1-infected patients enrolled in a randomized controlled trial with a follow-up of 144 weeks of ART. Enzyme-linked immunosorbent assay was performed to evaluate plasma IL-18. Long-term virological response was defined as HIV-1 RNA <20 copies/mL at week 144. Results: Among the 173 enrolled patients, the long-term virological response rate was 93.1%. Patients with a long-term virological response had significantly lower levels of week 24 IL-18 than non-responders. We defined 64 pg./mL, with a maximum sum of sensitivity and specificity, as the optimal cutoff value of week 24 IL-18 level to predict long-term virological response. After adjusting for age, gender, baseline CD4+ T-cell count, baseline CD4/CD8 ratio, baseline HIV-1 RNA level, HIV-1 genotype and treatment strategy, we found that lower week 24 IL-18 level (≤64 vs. >64 pg./mL, a OR 19.10, 95% CI: 2.36-154.80) was the only independent predictor of long-term virological response. Conclusion: Early on-treatment plasma IL-18 could act as a promising indicator for long-term virological response in patients with HIV-1 infection. Chronic immune activation and inflammation may represent a potential mechanism; further validation is necessary.

The delayed clearance of Talaromyces marneffei in blood culture may be associated with higher MIC of voriconazole after antifungal therapy among AIDS patients with talaromycosis.

OBJECTIVES: This study aimed to investigate the influencing factors of delayed clearance of Talaromyces marneffei (T. marneffei) in blood culture of patients with acquired immune deficiency syndrome (AIDS) complicated with talaromycosis after antifungal therapy. METHODS: The patients with AIDS complicated with talaromycosis were retrospectively enrolled, and divided into two groups according to the blood T. marneffei culture results in two weeks after antifungal therapy. The baseline clinical data were collected and the antifungal susceptibility of T. marneffei was tested. RESULTS: A total of 190 patients with AIDS and talaromycosis were enrolled, of whom 101 cases remained positive for T. marneffei (Pos-group) while the other 89 cases were negative in blood culture (Neg-group) after two weeks' antifungal treatment. The Pos-group had a higher baseline Aspartate aminotransferase (AST, 78.5 vs. 105 U/L; P = 0.073) and lower CD4+ T cells level (11 vs. 7 cells/µl; P = 0.061). The percentage of isolates with higher MICs of voriconazole (VOR) and fluconazole (FLU) in the Pos-group were significantly higher than those in the Neg-group (χ2 = 12.623, P < 0.001 and χ2 = 9.356, P = 0.002, respectively). By multivariate logistic regression, the MIC value for VOR was identified as the prognostic variable that may influence the clearance of T. marneffei in blood culture after antifungal therapy among AIDS patients with talaromycosis. CONCLUSIONS: The delayed negative conversion of blood T. marneffei-culture may be associated with some factors especially higher MIC of VOR, indicating the possibility of drug resistance of T. marneffei.

Characteristics and clinical significance of plasma IL-18, sCD14, and sCD163 levels in patients with HIV-1 infection.

Biomarkers of monocyte-macrophages activation and inflammation in plasma such as interleukin-18 (IL-18), soluble leukocyte differentiation antigen 14 (sCD14), and sCD163 are associated with disease severity and prognosis in HIV-1 infected patients, however, their relationships with efficacy of antiretroviral therapy (ART) need further investigation. We aimed to characterize and explore the clinical significance of plasma IL-18, sCD14, and sCD163 in this population. This was a retrospective cohort study consisting of HIV-1 infected patients enrolled in a randomized, controlled, open-label, noninferiority trial (ALTERLL study), with follow-up time points including initiation of ART (baseline), 12-, 24- and 48-weeks of treatment. Plasma levels of IL-18, sCD14, and sCD163 were measured using the enzyme-linked immunosorbent assay method. Viral suppression was defined as HIV-1 RNA < 20 copies/ml. Among the 193 studied patients (median age of 29.0 years, 180 males), IL-18 and sCD163 had U-shaped regression curves and sCD14 had an inverted U-shaped regression curve while the virus was decreased and immune function recovered. Patients with higher levels of IL-18 or lower levels of sCD163 at baseline were less likely to achieve viral suppression at Week 12 or Week 24 of treatment, respectively. In multivariate analysis, baseline sCD163 ≤ 500 pg/ml (adjusted odds ratio 0.33, 95% confidence interval 0.16-0.68) was independently associated with a lower rate of viral suppression at Week 24 of treatment. In conclusion, we demonstrated different dynamic changes among IL-18, sCD14, and sCD163 after ART. Baseline sCD163 level could be a potential predictor of early virological response to ART. Further validation and mechanistic research are needed.

Talaromyces marneffei Mp1p Antigen Detection may Play an Important Role in the Early Diagnosis of Talaromycosis in Patients with Acquired Immunodeficiency Syndrome.

Talaromycosis is a life-threatening fungal disease commonly seen in patients with acquired immunodeficiency syndrome (AIDS), which is endemic in Southern China and Southeast countries. The diagnostic methods available for talaromycosis are relatively time-consuming and yield a high mortality. Therefore, early diagnosis of talaromycosis is extremely important. We aimed to determine a potential method for assisting in its early diagnosis. A total of 283 patients with AIDS admitted to our hospital were prospectively included in this cross-sectional study and divided into those with Talaromyces marneffei (TSM group, n = 93) and those without Talaromyces marneffei (non-TSM group, n = 190). The diagnostic accuracy of the Mp1p enzyme immunoassay (EIA), galactomannan (GM) assay, and blood culture performed within 3 days of hospitalisation were evaluated, using talaromycosis confirmed by culture and/or pathology as the gold standard. The positivity rates in the Mp1p EIA, GM assay, and blood culture were 72%, 64.5%, and 81.7%, respectively, in the TSM group. The sensitivity, specificity, and positive and negative predictive values of the Mp1p EIA were 72.0% (67/93), 96.8% (184/190), 91.8% (67/73), and 87.6% (184/210), respectively. The Mp1p EIA showed a substantial agreement with the gold standard (kappa: 0.729) and superiority to the GM assay (kappa: 0.603); it also showed a superior diagnostic accuracy in the patients with CD4+ counts of < 50 cells/µL compared to those with CD4+ counts ranged from 50-100 cells/µL. The Mp1p EIA has the advantage of assisting in the early diagnosis of talaromycosis in patients with AIDS, especially those with low CD4+ counts.

COVID-19 induces new-onset insulin resistance and lipid metabolic dysregulation via regulation of secreted metabolic factors.

Abnormal glucose and lipid metabolism in COVID-19 patients were recently reported with unclear mechanism. In this study, we retrospectively investigated a cohort of COVID-19 patients without pre-existing metabolic-related diseases, and found new-onset insulin resistance, hyperglycemia, and decreased HDL-C in these patients. Mechanistically, SARS-CoV-2 infection increased the expression of RE1-silencing transcription factor (REST), which modulated the expression of secreted metabolic factors including myeloperoxidase, apelin, and myostatin at the transcriptional level, resulting in the perturbation of glucose and lipid metabolism. Furthermore, several lipids, including (±)5-HETE, (±)12-HETE, propionic acid, and isobutyric acid were identified as the potential biomarkers of COVID-19-induced metabolic dysregulation, especially in insulin resistance. Taken together, our study revealed insulin resistance as the direct cause of hyperglycemia upon COVID-19, and further illustrated the underlying mechanisms, providing potential therapeutic targets for COVID-19-induced metabolic complications.

The Association of TLR2, TLR3, and TLR9 Gene Polymorphisms With Susceptibility to Talaromycosis Among Han Chinese AIDS Patients in Guangdong.

Background: Talaromycosis (TM) caused by Talaromyces marneffei (T. marneffei) is a growing public health concern. Although Toll-like receptor (TLR) genes play a critical role in the host defense against fungal infection, the influence of polymorphisms in these genes on the susceptibility of acquired immune deficiency syndrome (AIDS) patients to TM remains unknown. This study aims to uncover the associations of single nucleotide polymorphisms (SNPs) in TLR genes with TM susceptibility among patients with AIDS. Methods: Altogether 200 AIDS patients complicated with TM, 200 matched AIDS patients without TM, and 76 healthy controls (HCs) were enrolled in this case-control study. In total, 23 SNPs in the TLR2, TLR4, and TLR9 genes, which may influence the susceptibility of AIDS patients to TM, were checked by the time of flight mass spectrometry (TOF/MS) method among these Han Chinese subjects. Results: No significant differences in genotype or allele frequencies of selected SNPs were found among the TM group, Non-TM group, and HC group. Haplotype analysis also demonstrated no correlation of these SNPs with TM. However, subgroup analysis showed that the genotype TT and the T allele in TLR2 SNP rs1339 were more frequent in typical TM cases than controls (50.0 vs. 35.8%, 70.5 vs. 59.7%); the frequency of the GT genotype in TLR2 SNP rs7656411 was markedly higher in severe TM cases compared to controls (57.8 vs. 34.4%). Conclusion: Our results demonstrate a genetic connection of TLR2 SNPs rs1339 and rs7656411 with an increased susceptibility and severity of TM among Han Chinese populations.

Antiretroviral Long-Term Efficacy and Resistance of Lopinavir/Ritonavir Plus Lamivudine in HIV-1-Infected Treatment-Naïve Patients (ALTERLL): 144-Week Results of a Randomized, Open-Label, Non-Inferiority Study From Guangdong, China.

Dual therapy with lopinavir/ritonavir (LPV/r) plus lamivudine (3TC) has been demonstrated to be non-inferior to the triple drug regimen including LPV/r plus two nucleoside reverse transcriptase inhibitors (NRTIs) in 48-week studies. However, little is known about the long-term efficacy and drug resistance of this simplified strategy. A randomized, controlled, open-label, non-inferiority trial (ALTERLL) was conducted to assess the efficacy, drug resistance, and safety of dual therapy with LPV/r plus 3TC (DT group), compared with the first-line triple-therapy regimen containing tenofovir (TDF), 3TC plus efavirenz (EFV) (TT group) in antiretroviral therapy (ART)-naïve HIV-1-infected adults in Guangdong, China. The primary endpoint was the proportion of patients with plasma HIV-1 RNA < 50 copies/ml at week 144. Between March 1 and December 31, 2015, a total of 196 patients (from 274 patients screened) were included and randomly assigned to either the DT group (n = 99) or the TT group (n = 97). In the primary intention-to-treat (ITT) analysis at week 144, 95 patients (96%) in the DT group and 93 patients (95.9%) in the TT group achieved virological inhibition with plasma HIV-1 RNA <50 copies/ml (difference: 0.1%; 95% CI, -4.6-4.7%), meeting the criteria for non-inferiority. The DT group did not show significant differences in the mean increase in CD4+ cell count (247.0 vs. 204.5 cells/mm3; p = 0.074) or the CD4/CD8 ratio (0.47 vs. 0.49; p = 0.947) from baseline, or the inflammatory biomarker levels through week 144 compared with the TT group. For the subgroup analysis, baseline high viremia (HIV-1 RNA > 100,000 copies/ml) and genotype BC did not affect the primary endpoint or the mean increase in CD4+ cell count or CD4/CD8 ratio from baseline at week 144. However, in patients with genotype AE, the DT group showed a higher mean increase in CD4+ cell count from baseline through 144 weeks than the TT group (308.7 vs. 209.4 cells/mm3; p = 0.038). No secondary HIV resistance was observed in either group. Moreover, no severe adverse event (SAE) or death was observed in any group. Nonetheless, more patients in the TT group (6.1%) discontinued the assigned regimen than those in the DT group (1%) due to adverse events. Dual therapy with LPV/r plus 3TC manifests long-term non-inferior therapeutic efficacy, low drug resistance, good safety, and tolerability compared with the first-line triple-therapy regimen in Guangdong, China, indicating dual therapy is a viable alternative in resource-limited areas. Clinical Trial Registration: [http://www.chictr.org.cn], identifier [ChiCTR1900024611].

The clinical significance of myeloid-derived suppressor cells in dengue fever patients.

BACKGROUND: Myeloid-derived suppressor cells (MDSCs) play immunosuppressive roles in cancers and some infectious diseases; however, their role in dengue fever (DF) remains unknown. This study evaluated the clinical significance of MDSCs in DF patients. METHODS: This study comprised 178 non-severe DF patients, 20 non-dengue fever (NDF) controls, and 30 healthy donors. The DF patients were divided into the following five groups based on the fever duration from its onset to the day of sample collection: fever duration of 1-2, 3-4, 5-6, 7-8, and > 9 days. Among these DF patients, 14 were monitored for eight days, and their peripheral blood samples were collected every two days. The mononuclear cells were isolated and analyzed using flow cytometry. The correlation between the MDSCs and clinical and immunological indicators of the DF patients was evaluated using Spearman analysis. RESULTS: The count of the peripheral blood MDSCs, especially monocytic MDSCs, of the 178 DF patients were dramatically higher than those of the NDF and healthy controls, and remarkably decreased with the fever duration. Moreover, the MDSC count correlated with some indicators, including the dengue viral load (rho = 0.367, p < .001), body temperature (rho = 0.263, p = .005), prothrombin time (rho = 0.475, p < .001), CD4+ T cell number (rho = - 0.317, p < .001), CD8+ T cell number (rho = - 0.361, p < .001), "programmed cell death protein 1" (PD-1) (rho = - 0.347, p < .001), "T cell immunoglobulin domain and mucin domain-3" (Tim3) (rho = - 0.258, p = .001), interferon-α (IFN-α) (rho = 0.43, p < .001), and "regulated upon activation normal T-cell expressed and secreted" (RANTES) (rho = 0.278, p = .019). Furthermore, the level of arginase-1, but not nitric oxide, was higher in the DF patients than in the healthy controls and was closely related to the number of MDSCs (rho = 0.265, p = .024). CONCLUSIONS: Our study reveals a significant correlation between MDSCs and DF clinical indicators, posing MDSCs as potential target cells for DF treatment.

Clinical significance and functional studies of myeloid-derived suppressor cells in chronic hepatitis C patients.

PURPOSE: Myeloid-derived suppressor cells (MDSCs) are known to accumulate under some pathologic conditions and suppress immune system in a variety of ways. This study aims to evaluate the significance of MDSCs in chronic Hepatitis C (CHC) patients. METHODS: 14 CHC patients and healthy donors were enrolled and subject to antiviral therapy including Peg-INF-alpha and Ribavirin for 48 weeks. The peripheral blood mononuclear cells (PBMCs) were collected at different weeks post-therapy and MDSC frequency was analyzed by flow cytometry. The correlation between MDSCs level with CHC disease parameters was analyzed by Spearman's rank test. The suppressive function of MDSCs from CHC patients and the underlying mechanism was further evaluated. RESULTS: A significant elevation of MDSCs was observed in the peripheral blood of treatment-naive CHC patients compared with healthy donors. The level of MDSCs in CHC patients correlated with plasma HCV-RNA (r = 0.7164, p = 0.0039), blood aminotransaminase (r = 0.6116, p = 0.021), and activated CD38(+) T cells (CD4(+): r = 0.6649, p = 0.0095; CD8(+): r = 0.6189, p = 0.0189). Initiation of clinical therapy reduced MDSC levels as early as 4 weeks, while it rebounded at week 12 post-therapy in patients. CHC-derived MDSCs could suppress T cell function in an arginase-1-dependent manner, that was distinct from the HCV core protein-generated MDSCs as previously reported. CONCLUSION: Our study reveals a significant correlation between MDSC levels with HCV disease progression, and their response to antiviral therapy. The arginase-1-dependent mechanism of MDSCs from CHC patients indicates that arginase-1 may be promising target for HCV immunotherapy.

Expansion of monocytic myeloid-derived suppressor cells dampens T cell function in HIV-1-seropositive individuals.

T lymphocyte dysfunction contributes to human immunodeficiency virus type 1 (HIV-1) disease progression by impairing antivirus cellular immunity. However, the mechanisms of HIV-1 infection-mediated T cell dysfunction are not completely understood. Here, we provide evidence that expansion of monocytic myeloid-derived suppressor cells (M-MDSCs) suppressed T cell function in HIV-1-infected individuals. We observed a dramatic elevation of M-MDSCs (HLA-DR(-/low) CD11b(+) CD33(+/high) CD14(+) CD15(-) cells) in the peripheral blood of HIV-1-seropositive subjects (n = 61) compared with healthy controls (n = 51), despite efficacious antiretroviral therapy for nearly 2 years. The elevated M-MDSC frequency in HIV-1(+) subjects correlated with prognostic HIV-1 disease markers, including the HIV-1 load (r = 0.5957; P < 0.0001), CD4(+) T cell loss (r = -0.5312; P < 0.0001), and activated T cells (r = 0.4421; P = 0.0004). Functional studies showed that M-MDSCs from HIV-1(+) subjects suppressed T cell responses in both HIV-1-specific and antigen-nonspecific manners; this effect was dependent on the induction of arginase 1 and required direct cell-cell contact. Further investigations revealed that direct HIV-1 infection or culture with HIV-1-derived Tat protein significantly enhanced human MDSC generation in vitro, and MDSCs from healthy donors could be directly infected by HIV-1 to facilitate HIV-1 replication and transmission, indicating that a positive-feedback loop between HIV-1 infection and MDSC expansion existed. In summary, our studies revealed a novel mechanism of T cell dysfunction in HIV-1-infected individuals and suggested that targeting MDSCs may be a promising strategy for HIV-1 immunotherapy.