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Raising a heterologous tier 2 neutralizing antibody (nAb) response remains a daunting task for HIV vaccine development. In this study, we explored the utility of diverse HIV-1 envelope (Env) immunogens in a sequential immunization scheme as a solution to this task. This exploration stemmed from the rationale that gp145, a membrane-bound truncation form of HIV Env, may facilitate the focusing of induced antibody response on neutralizing epitopes when sequentially combined with the soluble gp140 form as immunogens in a prime-boost mode. We first showed that gp140 DNA prime-gp145 Tiantan vaccinia (TV) boost likely represents a general format for inducing potent nAb response in mice. However, when examined in rhesus macaque, this modality showed little effectiveness. To improve the efficacy, we extended the original modality by adding a strong protein boost, namely native-like SOSIP.664 trimer displayed on ferritin-based nanoparticle (NP), which was generated by a newly developed click approach. The resulting three-immunization regimen succeeded in eliciting tier-2 nAb response with substantial breadth when implemented in rhesus macaque over a short 8-week schedule. Importantly, the elicited nAb response was able to effectively contain viremia upon a heterologous SHIV challenge. Collectively, our studies highlighted that diversification of Env immunogens, in both types and formulations, under the framework of a sequential immunization scheme might open new opportunity toward HIV vaccine development. Electronic supplementary material The online version of this article (10.1007/s12250-021-00361-3) contains supplementary material, which is available to authorized users.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and coronavirus disease 2019 (COVID-19) continue to impact countries worldwide. At present, inadequate diagnosis and unreliable evaluation systems hinder the implementation and development of effective prevention and treatment strategies. Here, we conducted a horizontal and longitudinal study comparing the detection rates of SARS-CoV-2 nucleic acid in different types of samples collected from COVID-19 patients and SARS-CoV-2-infected monkeys. We also detected anti-SARS-CoV-2 antibodies in the above clinical and animal model samples to identify a reliable approach for the accurate diagnosis of SARS-CoV-2 infection. Results showed that, regardless of clinical symptoms, the highest detection levels of viral nucleic acid were found in sputum and tracheal brush samples, resulting in a high and stable diagnosis rate. Anti-SARS-CoV-2 immunoglobulin M (IgM) and G (IgG) antibodies were not detected in 6.90% of COVID-19 patients. Furthermore, integration of nucleic acid detection results from the various sample types did not improve the diagnosis rate. Moreover, dynamic changes in SARS-CoV-2 viral load were more obvious in sputum and tracheal brushes than in nasal and throat swabs. Thus, SARS-CoV-2 nucleic acid detection in sputum and tracheal brushes was the least affected by infection route, disease progression, and individual differences. Therefore, SARS-CoV-2 nucleic acid detection using lower respiratory tract samples alone is reliable for COVID-19 diagnosis and study.新型冠状病毒（SARS-CoV-2）及其造成的肺炎（COVID-19）持续严重影响世界各国。稳定可靠的诊断方法和评价系统的欠缺严重阻碍了有效预防和治疗策略的实施和发展。该研究通过横向和纵向研究，比较分析来源于COVID-19患者和SARS-CoV-2感染猴的不同类型样本中SARS-CoV-2的核酸检出率，分析COVID-19患者和SARS-CoV-2感染猴血清中抗SARS-CoV-2抗体的阳性率，以评估SARS-CoV-2感染诊断方法的可靠性。结果显示无论感染者的临床症状如何，痰液和气管刷样品中病毒核酸检出率较高，感染确诊率高，诊断结果稳定。而6.90% COVID-19患者血清中未检测到抗SARS-CoV-2免疫球蛋白M和G。此外，同时采集不同类型样本并结合其核酸检测的结果并不能提高诊断率。另外，与鼻拭子和咽拭子相比，痰和气管刷中SARS-CoV-2病毒载量持续时间较长，动态变化较明显。因此，痰和气管刷中SARS-CoV-2核酸检测受感染途径、疾病进展和个体差异的影响较小，用下呼吸道标本进行SARS-CoV-2核酸检测是SARS-CoV-2感染诊断和研究的可靠依据。.

As of June 2020, Coronavirus Disease 2019 (COVID-19) has killed an estimated 440 000 people worldwide, 74% of whom were aged ≥65 years, making age the most significant risk factor for death caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. To examine the effect of age on death, we established a SARS-CoV-2 infection model in Chinese rhesus macaques ( Macaca mulatta) of varied ages. Results indicated that infected young macaques manifested impaired respiratory function, active viral replication, severe lung damage, and infiltration of CD11b + and CD8 + cells in lungs at one-week post infection (wpi), but also recovered rapidly at 2 wpi. In contrast, aged macaques demonstrated delayed immune responses with a more severe cytokine storm, increased infiltration of CD11b + cells, and persistent infiltration of CD8 + cells in the lungs at 2 wpi. In addition, peripheral blood T cells from aged macaques showed greater inflammation and chemotaxis, but weaker antiviral functions than that in cells from young macaques. Thus, the delayed but more severe cytokine storm and higher immune cell infiltration may explain the poorer prognosis of older aged patients suffering SARS-CoV-2 infection.

Understanding the pathological features of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in an animal model is crucial for the treatment of coronavirus disease 2019 (COVID-19). Here, we compared immunopathological changes in young and old rhesus macaques (RMs) before and after SARS-CoV-2 infection at the tissue level. Quantitative analysis of multiplex immunofluorescence staining images of formalin-fixed paraffin-embedded (FFPE) sections showed that SARS-CoV-2 infection specifically induced elevated levels of apoptosis, autophagy, and nuclear factor kappa-B (NF-κB) activation of angiotensin-converting enzyme 2 (ACE2)+ cells, and increased interferon α (IFN-α)- and interleukin 6 (IL-6)-secreting cells and C-X-C motif chemokine receptor 3 (CXCR3)+ cells in lung tissue of old RMs. This pathological pattern, which may be related to the age-related pro-inflammatory microenvironment in both lungs and spleens, was significantly correlated with the systemic accumulation of CXCR3+ cells in lungs, spleens, and peripheral blood. Furthermore, the ratio of CXCR3+ to T-box protein expression in T cell (T-bet)+ (CXCR3+/T-bet+ ratio) in CD8+ cells may be used as a predictor of severe COVID-19. These findings uncovered the impact of aging on the immunopathology of early SARS-CoV-2 infection and demonstrated the potential application of CXCR3+ cells in predicting severe COVID-19.

Understanding the processes of immune regulation in patients infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is crucial for improving treatment. Here, we performed longitudinal whole-transcriptome RNA sequencing on peripheral blood mononuclear cell (PBMC) samples from 18 patients with coronavirus disease 2019 (COVID-19) during their treatment, convalescence, and rehabilitation. After analyzing the regulatory networks of differentially expressed messenger RNAs (mRNAs), microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) between the different clinical stages, we found that humoral immunity and type I interferon response were significantly downregulated, while robust T-cell activation and differentiation at the whole transcriptome level constituted the main events that occurred during recovery from COVID-19. The formation of this T cell immune response might be driven by the activation of activating protein-1 (AP-1) related signaling pathway and was weakly affected by other clinical features. These findings uncovered the dynamic pattern of immune responses and indicated the key role of T cell immunity in the creation of immune protection against this disease.

Chronic immune activation and systemic inflammation are underlying causes of acquired immunodeficiency syndrome (AIDS). Products of virus replication and microbial translocation, co-infection or opportunistic pathogens, and danger-associated molecular patterns have been reported to contribute to chronic immune activation and inflammation in human immunodeficiency virus type-1/simian immunodeficiency virus (HIV-1/SIV) infection or other disease. To develop new strategies and therapies for HIV-1/AIDS, we tested if the CD24 and Fc fusion protein (CD24Fc), which interacts with danger-associated molecular patterns and sialic acid binding Ig-like lectin to attenuate inflammation, can protect Chinese rhesus macaques (ChRMs) with SIV infection. We found that CD24Fc treatment decreased weight loss, wasting syndrome, intractable diarrhea, and AIDS morbidity and mortality, while it was well tolerated by SIV-infected animals. Corresponding to the elimination of intractable diarrhea, CD24Fc significantly reduced the expression of IL-6 and indoleamine 2, 3-dioxygenase-1 in peripheral blood mononuclear cell and inflammation in the ileum, colon and rectum based on the reduction of inflammatory cells, pathological scores and expression of inflammatory cytokines. Furthermore, although CD24Fc did not restore CD4+ T cell number or significantly change T cell subsets or CD4+ T cell activation, it maintained low levels of plasma soluble CD14, CD8+ T cell activation, viral load and proviral load in the peripheral blood mononuclear cells and marrow. These results suggested that CD24Fc confers protection to SIV-infected ChRMs against progression to AIDS. It was also implied that CD24Fc may be a potential therapeutic approach for the control of HIV-1/AIDS.

Chinese rhesus macaques (CRMs) are ideal experimental animals for studying the pathogenesis of human immunodeficiency virus (HIV) and simian immunodeficiency virus (SIV) and for vaccine research. SHIV89.6 has been reported to be an attenuated virus because, in most cases, SHIV89.6 infection only causes limited alteration of immune cells and tissues, and it has been used commonly for vaccine research. After two serial passages in vivo, SHIV (SHIV-89.6P) induces CD4 lymphopenia and an AIDS-like disease with wasting and opportunistic infections. However, the pathogenic ability of SHIV89.6 is not well understood. In this study, we found that 6 of 14 SHIV89.6-infected CRMs died within 127 weeks after infection. We found especially high immune activation, low IFN-α expression, and distinctive cytokine expression profiles in the infected and dead (ID) group of monkeys, while there was only few change in the CD4(+) T counts and distribution of T cell subsets in the ID group monkeys. Also, there was a similar dynamic of viral load between infected and surviving (IS) and ID group monkeys. Furthermore, we found various correlations among immune activation, IFN-α expression, and frequencies of cytokine-secreting cells. These results suggest that SHIV89.6 infections have pathogenic potential in CRMs and that high immune activation and abnormal expression of cytokines contribute to death of SHIV89.6-infected CRMs. This also implies that high immune activation may be relevant to dysfunction of immune cells. It is proposed that high immune activation and dysfunction of immune cells may be good predictors for disease progression and markers for therapy.

Macaca leonina (northern pig-tailed macaques, NPMs) have variable disease progression during SIVmac239 infection. In the present study, we analysed, for the first time, the correlations between T-cell phenotypes and disease progression in NPMs during SIVmac239 infection. In comparison to normal progressors (NPs), slow progressors (SPs) had lower chronic T-cell activation and exhaustion levels. In addition, SPs showed higher peripheral CD4+ T-cell count and CD4 : CD8 ratio, and lower plasma viral load than NPs. CD4+ T-cell count and CD4 : CD8 ratio decreased more sharply in NPs than in SPs. Furthermore, T cells in NPs were more highly differentiated, at least in acute infection, than in SPs. These results indicated that T-cell phenotypes were correlated with disease progression in SIVmac239-infected NPMs and these correlations may provide valuable guidance for the improvement of therapeutic strategies tested in NPMs.

The elderly population infected with HIV-1 is often characterized by the rapid AIDS progression and poor treatment outcome, possibly because of immunosenescence resulting from both HIV infection and aging. However, this hypothesis remains to be fully tested. Here, we studied 6 young and 12 old Chinese rhesus macaques (ChRM) over the course of three months after simian immunodeficiency virus (SIV) SIVmac239 infection. Old ChRM showed a higher risk of accelerated AIDS development than did young macaques, owing to rapidly elevated plasma viral loads and decreased levels of CD4+ T cells. The low frequency of naïve CD4+ T cells before infection was strongly predictive of an increased disease progression, whereas the severe depletion of CD4+ T cells and the rapid proliferation of naïve lymphocytes accelerated the exhaustion of naïve lymphocytes in old ChRM. Moreover, in old ChRM, a robust innate host response with defective regulation was associated with a compensation for naïve T cell depletion and a high level of immune activation. Therefore, we suggest that immunosenescence plays an important role in the accelerated AIDS progression in elderly individuals and that SIV-infected old ChRM may be a favorable model for studying AIDS pathogenesis and researching therapies for elderly AIDS patients.

Gradual depletion of CD4+ T cells is a typical characteristic of pathogenic SIV infection. Intriguingly, we find a spontaneous CD4+ T-cell homeostasis in northern pig-tailed macaques (Macaca leonina) during SIVmac239 infection.

Kaposi’s sarcoma-associated herpesvirus (KSHV) was first identified as the etiologic agent of Kaposi’s sarcoma (KS) in 1994. KSHV infection is necessary, but not sufficient for the development of Kaposi sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman disease (MCD). Advances in the prevention and treatment of KSHV-associated Diseases have been achieved, even though current treatment options are ineffective, or toxic to many affected persons. The identification of new targets for potential future therapies and the randomized trial to evaluate the efficacy of new antivirals are required.

HIV/AIDS is one of the most serious public health challenges globally. Despite the great efforts that are being devoted to prevent, treat and to better understand the disease, it is one of the main causes of morbidity and mortality worldwide. Currently, there are 30 drugs or combinations of drugs approved by FDA. Because of the side-effects, price and drug resistance, it is essential to discover new targets, to develop new technology and to find new anti-HIV drugs. This review summarizes the major targets and assays currently used in anti-HIV drug screening.

Human/simian immunodeficiency virus (HIV/SIV) infection can cause severe depletion of CD4(+) T cells in both plasma and mucosa; it also results in damage to the gut mucosa barrier, which makes the condition more conducive to microbial translocation. In this study, we used SIV-infected Chinese rhesus macaques to quantify the extent of microbial translocation and the function of immune cells in the entire gastrointestinal tract and to compare their differences between rapid and slow progressors. The results showed that in the slow progressors, microbial products translocated considerably and deeply into the lamina propria of the gut; the tissue macrophages had no significant differences compared with the rapid progressors, but there was a slightly higher percentage of mucosal CD8(+) T cells and a large amount of extracellular microbial products in the lamina propria of the intestinal mucosa of the slow progressors. The data suggested that although microbial translocation increased markedly, the mucosal macrophages and CD8(+) T cells were insufficient to clear the infiltrated microbes in the slow progressors. Also, therapies aimed at suppressing the translocation of microbial products in the mucosa could help to delay the progression of SIV disease.

Immune activation plays a significant role in the disease progression of HIV. Microbial products, especially bacterial lipopolysaccharide (LPS), contribute to immune activation. Increasing evidence indicates that T lymphocyte homeostasis disruptions are associated with immune activation. However, the mechanism by which LPS affects disruption of immune response is still not fully understood. Chronically SHIVB’WHU-infected Chinese rhesus macaques received 50 μg/kg body weight LPS in this study. LPS administration affected the virus/host equilibrium by elevating the levels of viral replication and activating T lymphocytes. LPS induced upregulation of CD8+naïve T cells and downregulated the number of CD4+and CD8+T effector memory cells. The downregulated effector memory cells are associated with a lower frequency of monofunctional and polyfunctional cells, and an upregulated programmed cell death-1 (PD-1) expression on CD4+and CD8+T cells was observed in monkeys after LPS stimulation. Our data provide new insights into the function of LPS in the immune activation in SHIV/HIV infection.

The postentry restriction of HIV-1 repli- cation in monocytes can be relieved when they differ- entiate to dendritic cells (DCs) or macrophages. Multi- ple mechanisms have been proposed to interpret the differentiation-dependent susceptibility of monocytes to HIV-1 infection, and the absence of host-cell-en- coded essential factors for HIV-1 completing the life cycle may provide an explanation. We have analyzed the gene expression profile in monocytes by mRNA mi- croarray and compared it with that of differentiated DCs. We demonstrated that purine-rich element bind- ing protein (Pur-), a host-cell-encoded ubiquitous, sequence-specific DNA- and RNA-binding protein, showed inadequate expression in monocytes, and the translation of Pur- mRNA was repressed by cell- expressed microRNA (miRNA). These Pur--targeted miRNAs modulated the differentiation-dependent sus- ceptibility of monocytes/DCs to HIV-1 infection, be- cause rescue of Pur- expression by transfection of miRNA inhibitors relieved the restriction of HIV-1 infection in monocytes, and ectopic input of miRNA mimics significantly reduced HIV-1 infection of mono- cyte-derived DCs (MDDCs). Collectively, our data em- phasized that inadequate host factors contribute to HIV-1 restriction in monocytes, and cellular miRNAs modulate differentiation-dependent susceptibility of host cells to HIV-1 infection. Elaboration of HIV-1 restriction in host cells facilitates our understanding of viral pathogenesis and the search for a new antiviral strategy.—Shen, C.-J., Jia, Y.-H., Tian, R.-R., Ding, M., Zhang, C., Wang, J.-H. Translation of Pur- is targeted by cellular miRNAs to modulate the differentiation- dependent susceptibility of monocytes to HIV-1 infec- tion. FASEB J. 26, 000 - 000 (2012). www.fasebj.org

Penicillium marneffei (P. marneffei) is considered an indicator pathogen of AIDS, and the endemicity and clinical features of P. marneffei have been described. While, how the co-infection of P. marneffei exacerbate deterioration of the immune response remains poorly understood. Here we isolated P. marneffei from the cutaneous lesions of AIDS patients and analyzed its effects on HIV-1-dendritic cells (DCs) interaction. We demonstrated that the monocyte-derived dendritic cells (MDDCs) could be activated by both thermally dimorphic forms of P. marneffei for significantly promoting HIV-1 trans-infection of CD4(+) T cells, while these activated MDDCs were refractory to HIV-1 infection. Mechanistically, P. marneffei-activated MDDCs endocytosed large amounts of HIV-1 and sequestrated the internalized viruses into tetrapasnin CD81(+) compartments potentially for proteolysis escaping. The activated MDDCs increased expression of intercellular adhesion molecule 1 and facilitated the formation of DC-T-cell conjunctions, where much more viruses were recruited. Moreover, we found that P. marneffei-stimulated MDDCs efficiently activated resting CD4(+) T cells and induced more susceptible targets for viral infection. Our findings demonstrate that DC function and its interaction with HIV-1 have been modulated by opportunistic pathogens such as P. marneffei for viral dissemination and infection amplification, highlighting the importance of understanding DC-HIV-1 interaction for viral immunopathogenesis elucidation.