Coinfecting viruses as determinants of HIV disease

Immunological and Neurological Signatures of the Co-Infection of HIV and HTLV: Current Insights and Future Perspectives

The human retroviruses HIV and HTLV-1/HTLV-2 are transmitted through similar pathways but result in markedly different diseases. This review delineates the immune-mediated mechanisms by which HTLVs influence HIV pathology in co-infected individuals. In the context of HIV co-infection, HTLV-1/HTLV-2 alter the cellular microenvironment to enhance their own survival while simultaneously impeding the progression of HIV. Despite the extensive body of literature on the biological and clinical implications of retroviral co-infections, decades of research have been marred by controversy due to several flawed epidemiological studies and anecdotal reports lacking robust statistical and scientific backing. Nevertheless, recent systematic and well-designed research has led to a growing consensus supporting at least three key conclusions: (1) co-infections of HIV-1 and HTLV-1 are frequently observed in patients with elevated CD4+ T-cell counts who present with lymphoma or neurological complications; (2) HIV-1 and HTLV-2 co-infections have been associated in some instances with a "long-term non-progressor" phenotype; (3) the differential function and/or overexpression of the HTLV-1 and HTLV-2 Tax proteins are likely crucial in the clinical and immunologic outcomes of HIV/HTLV-1 and -2 co-infections. The present review will provide a comprehensive account of research on retroviral co-infections, focusing particularly on their clinical manifestations and associated pathological features.

Human Immunodeficiency Virus-Human Pegivirus Coinfected Individuals Display Functional Mucosal-Associated Invariant T Cells and Follicular T Cells Irrespective of PD-1 Expression

Human pegivirus (HPgV) appears to alter the prognosis of HIV disease by modulating T cell homeostasis, chemokine/cytokine production, and T cell activation. In this study, we evaluated if HPgV had any 'favorable' impact on the quantity and quality of T cells in HIV-infected individuals. T cell subsets such as CD4lo, CD4hi, and CD8+ T cells, CD4+ MAIT cells, CD8+ MAIT cells, follicular helper T (TFH) cells, and follicular cytotoxic T (TFC) cells were characterized based on the expression of markers associated with immune activation (CD69, ICOS), proliferation (ki67), cytokine production (TNF-α, IFN-γ), and exhaustion (PD-1). HIV+HPgV+ individuals had lower transaminase SGOT (liver) and GGT (biliary) in the plasma than those who were HPgV-. HIV/HPgV coinfection was significantly associated with increased absolute CD4+ T cell counts. HIV+HPgV+ and HIV+HPgV- individuals had highly activated T cell subsets with high expression of CD69 and ICOS on bulk CD4+ and CD8+ T cells, CD4+ MAIT cells, CD8+ MAIT cells, and CXCR5+CD4+ T cells and CXCR5+CD8+ T cells compared with healthy controls. Irrespective of immune activation markers, these cells also displayed higher levels of PD-1 on CD4+ T and CD8+ T cells . Exploring effector functionality based on mitogen stimulation demonstrated increased cytokine production by CD4+ MAIT and CD8+ MAIT cells. Decrease in absolute CD4+ T cell counts correlated positively with intracellular IFN-γ levels by CD4lo T cells, whereas increase of the same correlated negatively with TNF-α in the CD4lo T cells of HIV+HPgV+ individuals. HIV/HPgV coinfected individuals display functional CD4+ and CD8+ MAIT, TFH, and TFC cells irrespective of PD-1 expression.

Co-Infections and Superinfections between HIV-1 and Other Human Viruses at the Cellular Level

Co-infection or superinfection of the host by two or more virus species is a common event, potentially leading to viral interference, viral synergy, or neutral interaction. The simultaneous presence of two or more viruses, even distantly related, within the same cell depends upon viral tropism, i.e., the entry of viruses via receptors present on the same cell type. Subsequently, productive infection depends on the ability of these viruses to replicate efficiently in the same cellular environment. HIV-1 initially targets CCR5-expressing tissue memory CD4+ T cells, and in the absence of early cART initiation, a co-receptor switch may occur, leading to the infection of naïve and memory CXCR4-expressing CD4+ T cells. HIV-1 infection of macrophages at the G1 stage of their cell cycle also occurs in vivo, broadening the possible occurrence of co-infections between HIV-1 and other viruses at the cellular level. Moreover, HIV-1-infected DCs can transfer the virus to CD4+ T cells via trans-infection. This review focuses on the description of reported co-infections within the same cell between HIV-1 and other human pathogenic, non-pathogenic, or low-pathogenic viruses, including HIV-2, HTLV, HSV, HHV-6/-7, GBV-C, Dengue, and Ebola viruses, also discussing the possible reciprocal interactions in terms of virus replication and virus pseudotyping.

Effect of Immune-Modulatory Interventions on Asymptomatic Cytomegalovirus Shedding During Suppressive Antiretroviral Therapy

Long-term consequences of human immunodeficiency virus (HIV) are likely the result of persistent inflammation and immune dysfunction of which cytomegalovirus (CMV) is a known contributor. We leveraged 2 AIDS Clinical Trials Group clinical trials exploring the effects of immune modulators (ruxolitinib and sirolimus) on inflammation in people with HIV on antiretroviral therapy to determine whether these interventions affected CMV shedding at various mucosal sites. Analyzing 635 mucosal samples collected, we found no significant difference in CMV levels across study arms or time points. Men had more CMV shedding than women. We did confirm an association between higher CMV DNA and immune markers associated with HIV persistence and HIV-associated mortality rates.

Comparison of the prevalence of Domestic Cat Hepadnavirus in a population of cats with uveitis and in a healthy blood donor cat population in the United Kingdom

OBJECTIVE

Domestic Cat Hepadnavirus (DCH) is a novel virus recently identified in the domestic cat. Currently, little is known regarding its clinical significance. The hepadnaviridae family includes the Hepatitis B Virus (HBV). Co-infection of HBV and Hepatitis C in humans increases the risk of uveitis. We aimed to determine whether DCH is present in the United Kingdom (UK) and whether DCH warrants investigation as a potential cause of uveitis in cats.

PROCEDURES

Clinical records from the Royal Veterinary College (RVC) and the Animal Health Trust (AHT) were reviewed for feline cases diagnosed with endogenous uveitis. A healthy control group was identified from cats presented to the RVC as blood donors. DNA was extracted from stored blood samples using commercially available kits. Polymerase chain reaction assays were performed to confirm the presence of feline DNA and to detect the presence of DCH DNA using previously described protocols.

RESULTS

Blood samples were available from 65 cats with endogenous uveitis and 43 healthy control cats. Two blood samples from cats with endogenous uveitis tested positive for the presence of DCH DNA. DCH DNA was not detected in the control group. There was no statistically significant difference between the prevalence of DCH between the groups.

CONCLUSIONS

Domestic Cat Hepadnavirus is present in the UK. This study failed to demonstrate a conclusive link between DCH and uveitis in cats, although further studies to investigate an association with other feline diseases are warranted.

COVID-19 and oral diseases: Assessing manifestations of a new pathogen in oral infections

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) is a recently identified virus responsible for life-threatening coronavirus disease 19 (COVID-19). The SARS-CoV-2 infected subjects can be asymptomatic or symptomatic; the later may present a wide spectrum of clinical manifestations. However, the impact of SARS-CoV-2 on oral diseases remain poorly studied. Detection of SARS-CoV-2 in saliva indicates existence of virus in the oral cavity. Recent studies demonstrating the expression of ACE-2, a SARS-CoV-2 entry receptor, in oral tissues further strengthens this observation. Cytokine storm in severe COVID-19 patients and copious secretion of pro-inflammatory cytokines (IL-6, IL-1β and TNF-α) in multiple symptomatic oral pathologies including periodontitis and periapical periodontitis suggests that inflammatory microenvironment is a hallmark of both COVID-19 and oral diseases. Hyperinflammation may provide conducive microenvironment for the growth of local oral pathogens or opportunistic microbes and exert detrimental impact on the oral tissue integrity. Multiple case reports have indicated uncharacterized oral lesions, symptomatic irreversible pulpitis, higher plaque index, necrotizing/desquamative gingivitis in COVID-19 patients suggesting that SARS-CoV-2 may worsen the manifestations of oral infections. However, the underlying factors and pathways remain elusive. Here we summarize current literature and suggest mechanisms for viral pathogenesis of oral dental pathology derived from oral microbiome and oral mucosa-dental tissue interactions. Longitudinal studies will reveal how the virus impairs disease progression and resolution post-therapy. Some relationships we suggest provide the basis for novel monitoring and treatment of oral viral disease in the era of SARS-CoV-2 pandemic, promoting evidence-based dentistry guidelines to diagnose virus-infected patients to improve oral health.

Seroprevalence of Human Herpesvirus Infections in Newly Diagnosed HIV-Infected Key Populations in Dar es Salaam, Tanzania

Background

Human herpesvirus (HHV) infections can significantly increase the risk of human immunodeficiency virus (HIV) transmission and accelerate disease progression. In the population at high risk of HIV infection, also termed as key populations (female sex workers (FSW), men who have sex with men (MSM), and people who inject drugs (PWID)), and their sexual partners, HHV infections can potentially compromise the efforts to prevent and control HIV infection. Here, we investigated the seroprevalence of HHV infections among HIV-infected key populations in Dar es Salaam, Tanzania. Methodology. We analyzed 262 archived serum samples of HIV-infected key populations from the integrated biobehavioral surveillance (IBBS) study conducted in Dar es Salaam, Tanzania. The enzyme-linked immunosorbent assay was used to determine IgG and IgM titers for cytomegalovirus (CMV) and herpes simplex virus (HSV) types 1 and 2.

Results

The overall seropositivity of HHV IgG was 92% (95% CI: 87.7–95.3%). HHV IgM was not detected in any of the samples. The most seroprevalent coinfection was CMV at 69.1% (181/262), followed by HSV-2 33.2% (87/262) and HSV-1 32.1% (84/262). HSV-2 infection differed by key population groups; it accounted for FSW (46.3%) (p=0.0001) compared to PWID (21.6%) and MSM (22.7%). In contrast, seroprevalence for CMV and HSV-1 was comparable across the key population groups; whereby, CMV was 62%, 75.3%, and 75% and HSV-1 was 26.4%, 39.2%, and 31.8% for FSW, MSM, and PWID, respectively. We also observed that multiple coinfections with CMV-HSV-2 (p=0.042) and CMV-HSV-1-HSV-2 (p=0.006) were significantly associated with key population aged above 40 years.

Conclusion

The IgG seroprevalence of CMV, HSV-1, and HSV-2 was high among HIV-positive key populations. These findings indicate that these individuals are prone to recurrence of HHV infections and may harbor replicating viruses that subsequently may affect HIV disease progression. Therefore, this warrants concerted efforts for integrated HIV and sexually transmitted infection prevention programs targeting key populations.

Insult to Injury-Potential Contribution of Coronavirus Disease-19 to Neuroinflammation and the Development of HIV-Associated Neurocognitive Disorders

Severe acute respiratory syndrome (SARS)-coronavirus (CoV)-2 is responsible for a new coronavirus disease known as coronavirus disease-19 (COVID-19). SARS-CoV-2 reports neurotropic properties and may have neurological implications, and this creates another health burden for people living with HIV. As yet, the impact of COVID-19 on (neuro)inflammation and the development of HIV-associated neurocognitive disorders (HAND) is not fully known. Here, we reviewed preliminary evidence that provides clues that COVID-19 may exacerbate inflammatory mechanisms related to the development of HAND.

Molecular detection and characterisation of Domestic Cat Hepadnavirus (DCH) from blood and liver tissues of cats in Malaysia

BACKGROUND

A new domestic cat hepadnavirus (DCH, family Hepadnaviridae) was first reported from whole blood samples of domestic cats in Australia in 2018, and from cat serum samples in Italy in 2019. The pathogenesis of DCH is unknown, but it was reported in cats with viraemia (6.5-10.8%), chronic hepatitis (43%) and hepatocellular carcinoma (28%). Recent reports suggest that DCH resembles the human hepatitis B virus (HBV) and its related hepatopathies. This study aims to detect and characterize DCH among domestic cats in Malaysia. A cross-sectional study was performed on 253 cats, of which 87 had paired blood and liver samples, entailing whole-genome sequencing and phylogenetic analysis of DCH from a liver tissue sample.

RESULTS

Among the 253 cats included in this study, 12.3% of the whole blood samples tested positive for DCH. The detection rate was significantly higher in pet cats (16.6%, n = 24/145) compared to shelter cats (6.5%, n = 7/108). Liver tissues showed higher a DCH detection rate (14.9%, n = 13/87) compared to blood; 5 out of these 13 cats tested positive for DCH in their paired liver and blood samples. Serum alanine transaminase (ALT) was elevated (> 95 units/L) in 12 out of the 23 DCH-positive cats (52.2%, p = 0.012). Whole-genome sequence analysis revealed that the Malaysian DCH strain, with a genome size of 3184 bp, had 98.3% and 97.5% nucleotide identities to the Australian and Italian strains, respectively. The phylogenetic analysis demonstrated that the Malaysian DCH genome was clustered closely to the Australian strain, suggesting that they belong to the same geographically-determined genetic pool (Australasia).

CONCLUSIONS

This study provided insights into a Malaysian DCH strain that was detected from a liver tissue. Interestingly, pet cats or cats with elevated ALT were significantly more likely to be DCH positive. Cats with positive DCH detection from liver tissues may not necessarily have viraemia. The impact of this virus on inducing liver diseases in felines warrants further investigation.

Semen virome of men with HIV on or off antiretroviral treatment

OBJECTIVES

Improving immune status of people living with HIV through antiretroviral therapy (ART) may also reduce shedding of other viruses in semen. We characterized the seminal fluid virome of men with HIV and tested potential associations between viruses present and CD4 T-cell count, HIV viremia, and antiretroviral therapy (ART) status.

DESIGN AND METHODS

Metagenomics was used to enrich and sequence viral nucleic acids from the seminal fluid of 55 semen samples from 42 men living with HIV from San Francisco with a median age of 33 (IQR, 28.7-45) and median CD4 T-cell counts of 837 cells/μl (IQR, 258-1571 cells/μl). All samples were collected between 2005 and 2015, and ART status was ascertained from medical records.

RESULTS

Anelloviruses, cytomegalovirus (CMV), and multiple genotypes of human papillomaviruses were detected. Participants shed from 0 to 4 distinct human viruses. Longitudinally collected seminal fluid samples showed changes in the viruses shed. Viruses were more frequently shed by individuals with detectable HIV viremia (43.7 vs. 15.4%, P = 0.042). A trend was seen for increased shedding by individuals who were not on ART (42.8 vs. 17.8%, P = 0.082) or with CD4 T-cell count less than 350 cells/μl (35.3 vs. 20%, P = 0.27).

CONCLUSION

Seminal fluid from men with HIV from San Francisco contains nucleic acids from three different DNA viral families. A greater number of viruses, particularly CMV, were shed by participants with detectable HIV viremia (18.9 vs. 0%, P = 0.022). Control of viremia through ART may lower shedding of other viruses in semen in addition to HIV.

A Novel Hepadnavirus Identified in an Immunocompromised Domestic Cat in Australia

High-throughput transcriptome sequencing allows for the unbiased detection of viruses in host tissues. The application of this technique to immunosuppressed animals facilitates the detection of viruses that might otherwise be excluded or contained in immunocompetent individuals. To identify potential viral pathogens infecting domestic cats we performed high-throughput transcriptome sequencing of tissues from cats infected with feline immunodeficiency virus (FIV). A novel member of the Hepadnaviridae, tentatively named domestic cat hepadnavirus, was discovered in a lymphoma sample and its complete 3187 bp genome characterized. Phylogenetic analysis placed the domestic cat hepadnavirus as a divergent member of mammalian orthohepadnaviruses that exhibits no close relationship to any other virus. DNA extracted from whole blood from pet cats was positive for the novel hepadnavirus by PCR in 6 of 60 (10%) FIV-infected cats and 2 of 63 (3.2%) FIV-uninfected cats. The higher prevalence of hepadnavirus viraemia detected in FIV-infected cats mirrors that seen in human immunodeficiency virus-infected humans coinfected with hepatitis B virus. In summary, we report the first hepadnavirus infection in a carnivore and the first in a companion animal. The natural history, epidemiology and pathogenic potential of domestic cat hepadnavirus merits additional investigation.

A common anti-cytomegalovirus drug, ganciclovir, inhibits HIV-1 replication in human tissues ex vivo

BACKGROUND

Cytomegalovirus (CMV) is a common HIV-1 copathogen. Since CMV infection is an important contributor to immune activation, the driving force of HIV disease, an anti-CMV strategy might be beneficial to HIV-infected patients. Shin et al. (J Acquir Immune Defic Syndr 2014; 65:251-258) reported that anti-CMV therapy with valganciclovir in coinfected individuals results in a decrease of HIV viral load that is not accompanied by a decrease of immune activation. This suggests an alternative mechanism for HIV inhibition other than suppression of CMV-mediated inflammation.

METHOD

We evaluated the anti-HIV activity of ganciclovir (GCV), the active form of valganciclovir, on HIV replication in human tissues ex vivo.

RESULTS

We show that GCV has a direct suppressive activity on HIV replication in human tissues ex vivo, including laboratory strains, drug-resistant and primate HIV-1 isolates. We deciphered the mechanism of this inhibition and showed that GCV-TP is incorporated in the nascent DNA chain and acts as a delayed chain terminator.

CONCLUSION

Our results suggest that anti-CMV strategy using valganciclovir in HIV-1-infected individuals may reduce HIV-1 viral load not only indirectly by decreasing CMV-mediated immune activation but also directly by inhibiting HIV-1 reverse transcriptase.

Longitudinal Viral Dynamics in Semen During Early HIV Infection

Background

Multiple viruses coinfect the male genital tract, influencing each other’s replication and perhaps affecting human immunodeficiency virus (HIV) pathogenesis and disease progression.

Methods

This study included 453 longitudinal seminal samples from 195 HIV-infected men from the San Diego Primary Infection Resource Consortium and 67 seminal samples from HIV-negative healthy controls. Seminal HIV RNA and DNA from 7 human herpesviruses (HHVs) were measured by real-time polymerase chain reaction. Longitudinal shedding rates were determined by Kaplan-Meier survival analysis. Predictors of viral shedding were determined using backwards selection in a multivariable generalized estimating equation model.

Results

HIV-infected participants presented significantly increased rates of seminal HHV shedding compared with HIV-uninfected controls. Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) were the most commonly detected HHV in semen of HIV-infected participants. Persistent shedding was more common for CMV and EBV when compared to other HHVs. With exception of HHV-7, HHV shedding was not significantly influenced by HIV RNA levels, CD4+ cell counts, or antiretroviral therapy. Presence of CMV, EBV, and herpes simplex virus (HSV) were independent predictors of genital HIV RNA shedding after adjusting for plasma HIV RNA and longitudinal measurements.

Conclusions

Seminal replication of multiple HHVs is common in our HIV primary infection cohort. Genital replication of CMV and EBV was the most common and was significantly associated with seminal HIV RNA shedding. Prevalence of HSV shedding was lower and mostly intermittent, but its association with seminal HIV RNA was the strongest. Understanding the complex viral milieu in semen is important for HIV transmission but might also play a role in HIV pathogenesis and disease progression.

Partners in Crime: The Role of CMV in Immune Dysregulation and Clinical Outcome During HIV Infection

In the current era of combination antiretroviral therapy (ART), human immunodeficiency virus (HIV)-infected individuals are living longer and healthier lives. Nevertheless, HIV-infected persons are at greater risk for age-related disorders, which have been linked to residual immune dysfunction and inflammation. HIV-infected individuals are almost universally co-infected with cytomegalovirus (CMV) and both viruses are associated with inflammation-related morbidities. Therefore, a detailed investigation of the relationship between CMV and aging-related morbidities emerging during chronic HIV infection is warranted. Here, we review the literature on how CMV co-infection affects HIV infection and host immunity and we discuss the gaps in our knowledge that need elucidation.

Human Herpesviruses as Copathogens of HIV Infection, Their Role in HIV Transmission, and Disease Progression

Of eight human herpesviruses (HHVs), often, only herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) find mention in medical literature as both of these viruses are commonly associated with genital lesions and oral ulcers, commonly known as cold sores. However, role of human herpesviruses as copathogens and in aggravation and in the transmission of other human diseases, especially the Acquired immunodeficiency syndrome (HIV/AIDS) has only very recently been recognized. Therefore, screening and treating subclinical HHV infections may offer slowing of HIV infection, disease progression, and its transmission. Beside HSV-1 and HSV-2, HHV-3 a causative agent of herpes zoster remained one of the first manifestations of HIV disease before the era of highly active antiretroviral therapy (HAART). HHV-5 also known as human Cytomegalovirus infection remains a significant risk factor for HIV-associated mortality and morbidity even in HAART era. It is proposed that Cytomegalovirus viremia could be a better predictor of HIV disease progression than CD4+ T-lymphocyte count. The role of HHV-4 or Epstein-Burr virus and HHV-6, HHV-7, and HHV-8 is still being investigated in HIV disease progression. This review provides insight into the current understanding about these 8 HHVs, their co-pathogenesis, and role in HIV/AIDS disease progression. The review also covers recent literature in favor and against administering anti-HHV treatment along with HAART for slower AIDS progression and interrupted sexual transmission.

The Sordid Affair Between Human Herpesvirus and HIV

Both human immunodeficiency virus (HIV) and human herpesvirus (HHV) infections persist lifelong, and almost all individuals infected with HIV are also infected with ≥1 HHV. These coinfections are not independent processes or benign. In this review, we discuss how HHVs, and cytomegalovirus in particular, interact with concurrent HIV infection, and we describe the next steps necessary to understand and address these connections.

Seminal Shedding of CMV and HIV Transmission among Men Who Have Sex with Men

As in many urban areas in the United States, the largest burden of the HIV epidemic in San Diego is borne by men who have sex with men (MSM). Using data from well-characterized HIV transmitting and non-transmitting partner pairs of MSM in San Diego, we calculated the population attributable risk (PAR) of HIV transmissions for different co-infections common among MSM in this area. We found that over a third of HIV transmissions could be potentially attributed to genital shedding of cytomegalovirus (CMV) (111 transmission events), compared to 21% potentially attributed to bacterial sexually transmitted infections (STI) (62 events) and 17% to herpes simplex virus type-2 (HSV-2) (51 events). Although our study cannot infer causality between the described associations and is limited in sample size, these results suggest that interventions aimed at reducing CMV shedding might be an attractive HIV prevention strategy in populations with high prevalence of CMV co-infection.

Genital Cytomegalovirus Replication Predicts Syphilis Acquisition among HIV-1 Infected Men Who Have Sex with Men

Objective

Sexually transmitted infections (STI) are common among HIV-infected men who have sex with men (MSM). While behavioral factors are important in STI acquisition, other biological factors such as immune modulation due to chronic viral infection may further predispose to STI acquisition.

Design

Post Hoc analysis including data collected over 12 months of follow-up from 131 HIV-infected MSM receiving antiretroviral therapy and screened for incident bacterial STI every 3 months.

Methods

Genital secretions collected at baseline were used to measure herpesvirus replication and inflammatory cytokines. Baseline predictors of STI were determined using survival analysis of time to incident STI.

Results

All participants were seropositive for cytomegalovirus (CMV), and 52% had detectable genital CMV at baseline. Thirty-five individuals acquired STI during follow-up, sometimes with multiple pathogen (17 syphilis, 21 gonorrhea, 14 chlamydia). Syphilis acquisition was associated with genital CMV replication at baseline (19.1% CMV-shedders versus 4.8% non-shedders, p=0.03) and younger age (p=0.02). Lower seminal MCP-1 was associated with higher seminal CMV levels and with syphilis acquisition (p<0.01). For syphilis acquisition, in multivariable Cox-Proportional Hazard model adjusted hazard rates were 3.56 (95%CI:1.00–12.73) for baseline CMV replication and 2.50 (0.92–6.77) for younger age.

Conclusions

This post hoc analysis suggest that CMV-associated decrease in seminal MCP-1 levels might predispose HIV-infected MSM to syphilis acquisition, but not other STI. Future studies should determine underlying mechanisms and if a causal association exists.

Dendritic cell type-specific HIV-1 activation in effector T cells: implications for latent HIV-1 reservoir establishment

BACKGROUND

Latent HIV type I (HIV-1) infections can frequently occur in short-lived proliferating effector T lymphocytes. These latently infected cells could revert into resting T lymphocytes and thereby contribute to the establishment of the long-lived viral reservoir. Monocyte-derived dendritic cells can revert latency in effector T cells in vitro.

METHODS

Here we investigated the latency activation properties of tissue-specific immune cells, including a large panel of dendritic cell subsets, to explore in which body compartments effector T cells are most likely to maintain latent HIV-1 provirus and thus potentially contribute to the long-lived reservoir.

RESULTS

Our results demonstrate that blood or genital tract dendritic cells do not activate latent provirus in effector T cells, whereas gut or lymphoid dendritic cells induce virus production from latently infected effector T cells in our in-vitro model for latency. Toll-like receptor 3-induced interferon production by myeloid dendritic cells abolished the dendritic cells' ability to induce viral gene expression.

CONCLUSIONS

In this study, we show that HIV-1 provirus residing in effector T cells is activated from latency by tissue-specific dendritic cell subsets and other immune cells with remarkably different efficiencies.Our new assay system points to an important, neglected aspect of HIV-1 research: the ability of other immune cells, especially dendritic cells, to differentially affect latency establishment as well as virus reactivation.

HTLV-1/-2 and HIV-1 co-infections: retroviral interference on host immune status

The human retroviruses HIV-1 and HTLV-1/HTLV-2 share similar routes of transmission but cause significantly different diseases. In this review we have outlined the immune mediated mechanisms by which HTLVs affect HIV-1 disease in co-infected hosts. During co-infection with HIV-1, HTLV-2 modulates the cellular microenvironment favoring its own viability and inhibiting HIV-1 progression. This is achieved when the HTLV-2 proviral load is higher than that of HIV-1, and thanks to the ability of HTLV-2 to: (i) up-regulate viral suppressive CCL3L1 chemokine expression; (ii) overcome HIV-1 capacity to activate the JAK/STAT pathway; (iii) reduce the activation of T and NK cells; (iv) modulate the host miRNA profiles. These alterations of immune functions have been mainly attributed to the effects of the HTLV-2 regulatory protein Tax and suggest that HTLV-2 exerts a protective role against HIV-1 infection. Contrary to HIV-1/HTLV-2, the effect of HIV-1/HTLV-1 co-infection on immunological and pathological conditions is still controversial. There is evidence that indicates a worsening of HIV-1 infection, while other evidence does not show clinically relevant effects in HIV-positive people. Possible differences on innate immune mechanisms and a particularly impact on NK cells are becoming evident. The differences between the two HIV-1/HTLV-1 and HIV-1/HTLV-2 co-infections are highlighted and further discussed.

Public health strategies for prevention and control of HSV-2 in persons who use drugs in the United States

BACKGROUND

Herpes simplex virus type 2 (HSV-2) affects HIV acquisition, transmission, and disease progression. Effective medications for genital herpes and for HIV/AIDS exist. Parenteral transmission of HIV among persons who inject drugs is decreasing. Reducing sexual transmission of HIV and HSV-2 among persons who use drugs (PWUD; i.e., heroin, cocaine, "speedball", crack, methamphetamine through injection or non-injection) necessitates relevant services.

METHODS

We reviewed HSV-2 sero-epidemiology and HSV-2/HIV associations in U.S.-based studies with PWUD and the general literature on HSV-2 prevention and treatment published between 1995 and 2012. We used the 6-factor Kass framework to assess relevant HSV-2 public health strategies and services in terms of their goals and effectiveness; identification of, and minimization of burdens and concerns; fair implementation; and fair balancing of benefits, burdens, and concerns.

RESULTS

Eleven studies provided HSV-2 serologic test results. High HSV-2 sero-prevalence (range across studies 38-75%) and higher sero-prevalence in HIV-infected PWUD (97-100% in females; 61-74% in males) were reported. Public health strategies for HSV-2 prevention and control in PWUD can include screening or testing; knowledge of HSV-2 status and partner disclosure; education, counseling, and psychosocial risk-reduction interventions; treatment for genital herpes; and HIV antiretroviral medications for HSV-2/HIV co-infected PWUD.

CONCLUSIONS

HSV-2 sero-prevalence is high among PWUD, necessitating research on development and implementation of science-based public health interventions for HSV-2 infection and HSV-2/HIV co-infections, including research on effectiveness and cost-effectiveness of such interventions, to inform development and implementation of services for PWUD.

Microbicides: still a long road to success

The development of efficient microbicides, the topically applied compounds that protect uninfected individuals from acquiring HIV-1, is a promising strategy to contain HIV-1 epidemics. Such microbicides should of course possess anti-HIV-1 activity, but they should also act against other genital pathogens, which facilitate HIV-1 transmission. The new trend in microbicide strategy is to use drugs currently used in HIV-1 therapy. The success of this strategy is mixed so far and is impaired by our limited knowledge of the basic mechanisms of HIV-1 transmission as well as by the inadequacy of the systems in which microbicides are tested in preclinical studies.

Cervico-vaginal tissue ex vivo as a model to study early events in HIV-1 infection

Vaginal intercourse remains the most prevalent route of infection of women. In spite of many efforts, the detailed mechanisms of HIV-1 transmission in the female lower genital tract remain largely unknown. With all the obvious restrictions on studying these mechanisms in humans, their understanding depends on the development of adequate experimental models. Isolated cell cultures do not faithfully reproduce important aspects of cell-cell interactions in living tissues and tissue responses to pathogens. Explants and other types of ex vivo tissue models serve as a bridge between cell culture and tissues in vivo. Herein, we discuss various cervico-vaginal tissue models and their use in studying HIV vaginal transmission and consider future directions of such studies.

A new class of dual-targeted antivirals: monophosphorylated acyclovir prodrug derivatives suppress both human immunodeficiency virus type 1 and herpes simplex virus type 2

BACKGROUND

Human immunodeficiency virus type 1 (HIV-1) and herpes simplex virus type 2 (HSV-2) are responsible for 2 intersecting epidemics in which the disease caused by 1 virus facilitates the transmission of and pathogenesis by the other. Therefore, suppression of one virus infection will affect the other. Acyclovir, a common antiherpetic drug, was shown to directly suppress both viruses in coinfected tissues. However, both antiviral activities of acyclovir are dependent on phosphorylation by the nucleoside kinase activity of coinfecting human herpesviruses.

METHODS

We developed acyclovir ProTides, monophosphorylated acyclovir with the phosphate group masked by lipophilic groups to allow efficient cellular uptake, and investigated their antiviral potential in cell lines and in human tissues ex vivo.

RESULTS

Acyclovir ProTides suppressed both HIV-1 and HSV-2 at median effective concentrations in the submicromolar range in ex vivo lymphoid and cervicovaginal human tissues and at 3-12 micromol/L in CD4(+) T cells. Acyclovir ProTides retained activity against acyclovir-resistant HSV-2.

CONCLUSIONS

Acyclovir ProTides represent a new class of antivirals that suppress both HIV-1 and HSV-2 by directly and independently blocking the key replicative enzymes of both viruses. Further optimization of such compounds may lead to double-targeted antivirals that can prevent viral transmission and treat the 2 synergistic diseases caused by HIV-1 and HSV-2. To our knowledge, the acyclovir ProTides described here represent the first example of acyclic nucleoside monophosphate prodrugs being active against HIV-1.

A systematic approach to virus-virus interactions

A virus–virus interaction is a measurable difference in the course of infection of one virus as a result of a concurrent or prior infection by a different species or strain of virus. Many such interactions have been discovered by chance, yet they have rarely been studied systematically. Increasing evidence suggests that virus–virus interactions are common and may be critical to understanding viral pathogenesis in natural hosts. In this review we propose a system for classifying virus–virus interactions by organizing them into three main categories: (1) direct interactions of viral genes or gene products, (2) indirect interactions that result from alterations in the host environment, and (3) immunological interactions. We have so far identified 15 subtypes of interaction and assigned each to one of these categories. It is anticipated that this framework will provide for a more systematic approach to investigating virus–virus interactions, both at the cellular and organismal levels.

Detection of an infectious retrovirus, XMRV, in blood cells of patients with chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a debilitating disease of unknown etiology that is estimated to affect 17 million people worldwide. Studying peripheral blood mononuclear cells (PBMCs) from CFS patients, we identified DNA from a human gammaretrovirus, xenotropic murine leukemia virus-related virus (XMRV), in 68 of 101 patients (67%) as compared to 8 of 218 (3.7%) healthy controls. Cell culture experiments revealed that patient-derived XMRV is infectious and that both cell-associated and cell-free transmission of the virus are possible. Secondary viral infections were established in uninfected primary lymphocytes and indicator cell lines after their exposure to activated PBMCs, B cells, T cells, or plasma derived from CFS patients. These findings raise the possibility that XMRV may be a contributing factor in the pathogenesis of CFS.