Search Results (41)

Vpr, a virion-associated accessory virulence factor of HIV-1, promotes virus replication in both T cells and macrophages. Although Vpr’s early activity—antagonism of preintegration silencing and host restriction factors—has been documented, the relative contribution of virion-associated versus de novo expressed Vpr to HIV-1 replication fitness remains unclear. Here, we developed a T cell-based system that genetically separates early and late Vpr functions by combining tetracycline-inducible Vpr expression in CEM.SS T cells with vpr-deficient HIV-1 constructs and Gag p6 mutations that block Vpr packaging. CEM.SS T cells have been shown to recapitulate the positive effect of Vpr on HIV-1 replication observed in activated primary T cells. Using pairwise replication fitness assays under spreading infection conditions, we demonstrate that de novo synthesized Vpr exerts the dominant effect on HIV-1 replication in T cells, while virion-associated Vpr plays a lesser role. Somewhat unexpectedly, our findings reveal that antagonism of preintegration HIV-1 silencing by virion-associated Vpr is unlikely to be the major driver of enhanced HIV-1 replication in proliferating T cells. Instead, this function may play a more prominent role in the infection of non-dividing T cells and/or other cell types. Full article

Trichomonas vaginalis, a prevalent sexually transmitted protozoan parasite, is associated with adverse birth outcomes, increased risk of HIV and other sexually transmitted infections, infertility, and cervical cancer. Despite its widespread impact, trichomoniasis remains underdiagnosed and underreported globally. Trichomonas vaginalis virus (TVV), a double-stranded RNA (dsRNA) virus infecting T. vaginalis, could impact T. vaginalis pathogenicity. We provide an overview of TVV, including its genomic structure, transmission, impact on protein expression, role in 5-nitroimidazole drug susceptibility, and clinical significance. TVV is a ~5 kbp dsRNA virus enclosed within a viral capsid closely associated with the Golgi complex and plasma membrane of infected parasites. Hypothetical mechanisms of TVV transmission have been proposed. TVV affects protein expression in T. vaginalis, including cysteine proteases and surface antigens, thus impacting its virulence and ability to evade the immune system. Additionally, TVV may influence the sensitivity of T. vaginalis to treatment; clinical isolates of T. vaginalis not harboring TVV are more likely to be resistant to metronidazole. Clinically, TVV-positive T. vaginalis infections have been associated with a range in severity of genital signs and symptoms. Further research into interactions between T. vaginalis and TVV is essential in improving diagnosis, treatment, and the development of targeted interventions. Full article

Fungi such as Aspergillus fumigatus, Candida albicans, and Cryptococcus neoformans are opportunistic pathogens in humans. They usually infect individuals whose immune system is compromised due to either a primary infection, e.g., HIV/AIDS, or as part of treatment for another condition, e.g., stem cell or solid organ transplant. In hosts with a weakened immune system, these fungi can cause life-threatening infections. Unlike true pathogens, opportunistic pathogens do not have specific mechanisms to overcome a healthy host, requiring a different approach to understand how they cause infection. The ability of fungi to adapt to various environmental conditions, including the human host, is critical for virulence. In humans, micronutrient metals, such as iron, are sequestered to reduce serum concentrations, which helps to inhibit microbial growth. Other human tissues may increase metal concentrations to toxic levels to prevent infection by pathogens. The ability of fungi to acquire or detoxify nutrients, such as iron or copper, from the host is essential for the establishment of infection. In this review, the role of fungal nutrition will be discussed in relation to opportunistic fungal pathogens. It will focus on the acquisition of micronutrients, e.g., iron, copper, and zinc, and how this enables these fungi to circumvent host nutritional immunity. Full article

The evolutionary origin of the variants of concern (VOCs) of SARS-CoV-2, characterized by a large number of new substitutions and strong changes in virulence and transmission rate, is intensely debated. The leading explanation in the literature is a chronic infection in immunocompromised individuals, where the virus evolves before returning into the main population. The present article reviews less-investigated hypotheses of VOC emergence with transmission between acutely infected hosts, with a focus on the mathematical models of stochastic evolution that have proved to be useful for other viruses, such as HIV and influenza virus. The central message is that understanding the acting factors of VOC evolution requires the framework of stochastic multi-locus evolution models, and that alternative hypotheses can be effectively verified by fitting results of computer simulation to empirical data. Full article

The biological characteristics of early transmitted/founder (T/F) variants are crucial factors for viral transmission and constitute key determinants for the development of better therapeutics and vaccine strategies. The present study aimed to generate T/F viruses and to characterize their biological properties. For this purpose, we constructed 18 full-length infectious molecular clones (IMCs) of HIV from recently infected infants. All the clones were characterized genotypically through whole genome sequencing and phenotypically for infectivity, replication kinetics, co-receptor usage, as well as their susceptibility to neutralizing antibodies and entry inhibitors using standard virological assays. Genotypic analysis revealed that all the T/F clones were of non-recombinant subtype C, but some of them harboured the Y181C drug resistance mutation associated with resistance to the non-nucleoside reverse transcriptase inhibitor (NNRTI) class of antiretroviral drugs. In vitro studies showed that while all the IMCs were capable of replicating in PBMCs and utilized the CCR5 co-receptor for cellular entry, the drug-resistant variants had significantly lower replicative capacity and per particle infectivity than the drug-sensitive viruses. Both exhibited similar sensitivities to a standard panel of broadly neutralizing monoclonal antibodies and viral entry inhibitors. These findings suggest that despite their diminished replicative fitness, the drug-resistant T/F variants retain transmission fitness and remain susceptible to neutralizing antibody-based interventions and viral entry inhibitors. Full article

HIV-associated cardiovascular diseases remain a leading cause of death in people living with HIV/AIDS (PLWHA). Although antiretroviral drugs suppress the viral load, they fail to remove the virus entirely. HIV-1 Nef protein is known to play a role in viral virulence and HIV latency. Expression of Nef protein can be detected in different organs, including cardiac tissue. Despite the established role of Nef protein in HIV-1 replication, its impact on organ function inside the human body is not clear. To understand the effect of Nef at the organ level, we created a new Nef-transgenic (Nef-TG) mouse that expresses Nef protein in the heart. Our study found that Nef expression caused inhibition of cardiac function and pathological changes in the heart with increased fibrosis, leading to heart failure and early mortality. Further, we found that cellular autophagy is significantly inhibited in the cardiac tissue of Nef-TG mice. Mechanistically, we found that Nef protein causes the accumulation of Bcl2 and Beclin-1 proteins in the tissue, which may affect the cellular autophagy system. Additionally, we found Nef expression causes upregulation of the cellular senescence marker p21 and senescence-associated β-galactosidase expression. Our findings suggest that the Nef-mediated inhibition of autophagy and induction of senescence markers may promote aging in PLWHA. Our mouse model could help us to understand the effect of Nef protein on organ function during latent HIV infection. Full article

Female genital tract infections (FGTIs) include vaginal infections (e.g., bacterial vaginosis [BV]), endometritis, pelvic inflammatory disease [PID], and chorioamnionitis [amniotic fluid infection]. They commonly occur in women of reproductive age and are strongly associated with multiple adverse health outcomes including increased risk of HIV/sexually transmitted infection acquisition and transmission, infertility, and adverse birth outcomes such as preterm birth. These FGTIs are characterized by a disruption of the cervicovaginal microbiota which largely affects host immunity through the loss of protective, lactic acid-producing Lactobacillus spp. and the overgrowth of facultative and strict anaerobic bacteria. Prevotella species (spp.), anaerobic Gram-negative rods, are implicated in the pathogenesis of multiple bacterial FGTIs. Specifically, P. bivia, P. amnii, and P. timonensis have unique virulence factors in this setting, including resistance to antibiotics commonly used in treatment. Additionally, evidence suggests that the presence of Prevotella spp. in untreated BV cases can lead to infections of the upper female genital tract by ascension into the uterus. This narrative review aims to explore the most common Prevotella spp. in FGTIs, highlight their important role in the pathogenesis of FGTIs, and propose future research in this area. Full article

Cryptococcus neoformans is an opportunistic fungal pathogen that can cause severe meningoencephalitis in immunocompromised hosts and is a leading cause of death in HIV/AIDS patients. This pathogenic yeast is surrounded by a polysaccharide capsule that is critical for virulence and plays important roles in host-pathogen interactions. Understanding capsule biosynthesis is therefore key to defining the biology of C. neoformans and potentially discovering novel therapeutic targets. By exploiting methods to identify mutants deficient in capsule, June Kwon-Chung and other investigators have discovered numerous genes involved in capsule biosynthesis and regulation. Successful approaches have incorporated combinations of techniques including mutagenesis and systematic gene deletion; complementation and genetic screens; morphological examination, physical separation, and antibody binding; and computational modeling based on gene expression analysis. In this review, we discuss these methods and how they have been used to identify capsule mutants. Full article

The aim of the present study was to characterize biofilms formed by Candida spp. clinical isolates (n = 19), isolated from the oral mucosa of HIV-positive patients. For characterizing the biofilms formed by several Candida sp. strains, isolated from HIV-positive patients, in terms of formed biomass, matrix composition and antifungal susceptibility profile, clinical isolates (n = 19) were collected from oral mucosa and identified. The biofilm of the samples was cultured with fluconazole (1250 mg/L), voriconazole (800 mg/L), anidulafungin (2 mg/L) or amphotericin B (2 mg/L). Afterwards, the quantification of the total biomass was performed using crystal violet assay, while the proteins and carbohydrates levels were quantified in the matrix. The results showed a predominance of C. albicans, followed by C. krusei. Around 58% of the Candida spp. biofilm had susceptibility to fluconazole and voriconazole (800 mg/L), 53% to anidulafungin and 74% to amphotericin B. C. krusei presented both the lowest and the highest biofilm matrix contents in polysaccharides and proteins. The low resistance to antifungal agents reported here was probably due to the fact that none of the participants had a prolonged exposure to these antifungals. A predominance of less virulent Candida spp. strains with low or no resistance to antifungals was observed. This can be attributed to a low fungal selective pressure. This most probably happened due to a low fungal selective pressure but also due to a good adherence to HAART therapy, which guarantees a stable and stronger immune patient response. Full article

Fungal infections are an increasingly growing public health concern, and Cryptococcus is one of the most problematic fungal organisms causing substantial mortality and morbidity worldwide. Clinically, this high incidence of cryptococcosis is most commonly seen in immunocompromised patients, especially those who lack an adaptive T cell response, such as HIV/AIDS patients. However, patients with other underlying immunodeficiencies are also at an increased risk for cryptococcosis. The adaptive immune response, in particular the Th1/Th17 T-cell-mediated responses, to pulmonary Cryptococcus infections are required for host protection. Dendritic cells (DCs), encompassing multiple subsets identified to date, are recognized as the major professional antigen-presenting cell (APC) subset essential for the initiation and execution of T-cell immunity. Apart from their prominent role in orchestration of the adaptive arm of the immune defenses, DCs are fully armed cells from the innate immune system capable of the recognition, uptake, and killing of the fungal cells. Thus, DCs serve as a critical point for the endpoint outcomes of either fungal control or unrestrained fungal infection. Multiple studies have shown that DCs are required for anti-cryptococcal defense in the lungs. In addition, the role of DCs in Cryptococcus gattii infections is just starting to be elucidated. C. gattii has recently risen to prominence with multiple outbreaks in the US and Canada, demonstrating increased virulence in non-immunocompromised individuals. C. gattii infection fails to generate an inflammatory immune response or a protective Th1/Th17 T cell response, at least in part, through a lack of proper DC function. Here we summarize the multiple roles of DCs, including subsets of DCs in both mouse and human models, the roles of DCs during cryptococcal infection, and mechanisms by cryptococcal cells to attempt to undermine these host defenses. Full article

The global economic and healthcare crises experienced over the past three years, as a result of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has significantly impacted the commonplace habits of humans around the world. SARS-CoV-2, the virus responsible for the coronavirus 2019 (COVID-19) phenomenon, has contributed to the deaths of millions of people around the world. The potential diagnostic applications of microfluidic devices have previously been demonstrated to effectively detect and quasi-quantify several different well-known viruses such as human immunodeficiency virus (HIV), influenza, and SARS-CoV-2. As a result, microfluidics has been further explored as a potential alternative to our currently available rapid tests for highly virulent diseases to better combat and manage future potential outbreaks. The outbreak management during COVID-19 was initially hindered, in part, by the lack of available quantitative rapid tests capable of confirming a person’s active infectiousness status. Therefore, this review will explore the use of microfluidic technology, and more specifically RNA-based virus detection methods, as an integral part of improved diagnostic capabilities and will present methods for carrying the lessons learned from COVID-19 forward, toward improved diagnostic outcomes for future pandemic-level threats. This review will first explore the context of the COVID-19 pandemic and how diagnostic technology was shown to have required even greater advancements to keep pace with the transmission of such a highly infectious virus. Secondly, the historical significance of integrating microfluidic technology in diagnostics and how the different types of genetic-based detection methods may vary in their potential practical applications. Lastly, the review will summarize the past, present, and future potential of RNA-based virus detection/diagnosis and how it might be used to better prepare for a future pandemic. Full article

The clinical evolution of patients infected with the Severe Acute Respiratory Coronavirus type 2 (SARS-CoV-2) depends on the complex interplay between viral and host factors. The evolution to less aggressive but better-transmitted viral variants, and the presence of immune memory responses in a growing number of vaccinated and/or virus-exposed individuals, has caused the pandemic to slowly wane in virulence. However, there are still patients with risk factors or comorbidities that put them at risk of poor outcomes in the event of having the coronavirus infectious disease 2019 (COVID-19). Among the different treatment options for patients with COVID-19, virus-targeted measures include antiviral drugs or monoclonal antibodies that may be provided in the early days of infection. The present expert consensus is based on a review of all the literature published between 1 July 2021 and 15 February 2022 that was carried out to establish the characteristics of patients, in terms of presence of risk factors or comorbidities, that may make them candidates for receiving any of the virus-targeted measures available in order to prevent a fatal outcome, such as severe disease or death. A total of 119 studies were included from the review of the literature and 159 were from the additional independent review carried out by the panelists a posteriori. Conditions found related to strong recommendation of the use of virus-targeted measures in the first days of COVID-19 were age above 80 years, or above 65 years with another risk factor; antineoplastic chemotherapy or active malignancy; HIV infection with CD4+ cell counts < 200/mm³; and treatment with anti-CD20 immunosuppressive drugs. There is also a strong recommendation against using the studied interventions in HIV-infected patients with a CD4+ nadir <200/mm³ or treatment with other immunosuppressants. Indications of therapies against SARS-CoV-2, regardless of vaccination status or history of infection, may still exist for some populations, even after COVID-19 has been declared to no longer be a global health emergency by the WHO. Full article

Trichomonas vaginalis is responsible for 156 million new cases per year worldwide. When present asymptomatically, the parasite can lead to serious complications, such as development of cervical and prostate cancer. As infection increases the acquisition and transmission of HIV, the control of trichomoniasis represents an important niche for the discovery and development of new antiparasitic molecules. This urogenital parasite synthesizes several molecules that allow the establishment and pathogenesis of infection. Among them, peptidases occupy key roles as virulence factors, and the inhibition of these enzymes has become an important mechanism for modulating pathogenesis. Based on these premises, our group recently reported the potent anti-T. vaginalis action of the metal-based complex [Cu(phendione)₃](ClO₄)₂.4H₂O (Cu-phendione). In the present study, we evaluated the influence of Cu-phendione on the modulation of proteolytic activities produced by T. vaginalis by biochemical and molecular approaches. Cu-phendione showed strong inhibitory potential against T. vaginalis peptidases, especially cysteine- and metallo-type peptidases. The latter revealed a more prominent effect at both the post-transcriptional and post-translational levels. Molecular Docking analysis confirmed the interaction of Cu-phendione, with high binding energy (−9.7 and −10.7 kcal·mol⁻¹, respectively) at the active site of both TvMP50 and TvGP63 metallopeptidases. In addition, Cu-phendione significantly reduced trophozoite-mediated cytolysis in human vaginal (HMVII) and monkey kidney (VERO) epithelial cell lineages. These results highlight the antiparasitic potential of Cu-phendione by interaction with important T. vaginalis virulence factors. Full article

Viral quasispecies are distinct but closely related mutants formed by the disparity in viral genomes due to recombination, mutations, competition, and selection pressure. Theoretical derivation for the origin of a quasispecies is owed to the error-prone replication by polymerase and mutants of RNA replicators. Here, we briefly addressed the theoretical and mathematical origin of quasispecies and their dynamics. The impact of quasispecies for major salient human pathogens is reviewed. In the current global scenario, rapid changes in geographical landscapes favor the origin and selection of mutants. It comes as no surprise that a cauldron of mutants poses a significant risk to public health, capable of causing pandemics. Mutation rates in RNA viruses are magnitudes higher than in DNA organisms, explaining their enhanced virulence and evolvability. RNA viruses cause the most devastating pandemics; for example, members of the Orthomyxoviridae family caused the great influenza pandemic (1918 flu or Spanish flu), the SARS (severe acute respiratory syndrome) and MERS (Middle East respiratory syndrome) outbreak, and the human immunodeficiency viruses (HIV), lentiviruses of the Retroviridae family, caused worldwide devastation. Rapidly evolving RNA virus populations are a daunting challenge for the designing of effective control measures like vaccines. Developing awareness of the evolutionary dispositions of RNA viral mutant spectra and what influences their adaptation and virulence will help curtail outbreaks of past and future pathogens. Full article

Endophytic yeast species were studied in the internal tissues of ripe cultivated vegetables and fruits. A total of 19 yeast species, 11 ascomycete species, and 8 basidiomycete species were observed in the internal tissues of all fruits examined. The opportunistic yeast Candida parapsilosis was present in all plants studied. Several virulence factors (production of hydrolytic enzymes and sensitivity to antifungal agents) were examined in all 107 isolates of C. parapsilosis from the internal tissues of fruits. The most virulent isolates were found in vegetables. C. parapsilosis is widespread in nature and is often isolated from a variety of non-human sources. It is frequently involved in invasive infections that seriously affect human health. This species poses a high risk to immunocompromised individuals, such as HIV patients and surgical patients or children whose immune systems are not sufficiently mature. Since virulent isolates of Candida parapsilosis have been found in vegetables and fruits; their raw consumption may not be safe. Finally, we emphasize the importance of ongoing phenotypic and genetic studies of endophytic isolates of Candida parapsilosis and their comparison with clinical isolates. Full article