HIV-associated opportunistic CNS infections: pathophysiology, diagnosis and treatment

Microbiomes detected by cerebrospinal fluid metagenomic next-generation sequencing among patients with and without HIV with suspected central nervous system infection

BACKGROUND

Opportunistic infections in the central nervous system (CNS) can be a serious threat to people living with HIV. Early aetiological diagnosis and targeted treatment are crucial but difficult. Metagenomic next-generation sequencing (mNGS) has significant advantages over traditional detection methods. However, differences in the cerebrospinal fluid (CSF) microbiome profiles of patients living with and without HIV with suspected CNS infections using mNGS and conventional testing methods have not yet been adequately evaluated.

METHODS

We conducted a retrospective cohort study in the first hospital of Changsha between January 2019 and June 2022 to investigate the microbiomes detected using mNGS of the CSF of patients living with and without HIV with suspected CNS infections. The pathogens causing CNS infections were concurrently identified using both mNGS and traditional detection methods. The spectrum of pathogens identified was compared between the two groups.

RESULTS

Overall, 173 patients (140 with and 33 without HIV) with suspected CNS infection were enrolled in our study. In total, 106 (75.7%) patients with and 16 (48.5%) patients without HIV tested positive with mNGS (p = 0.002). Among the enrolled patients, 71 (50.7%) with HIV and five (15.2%) without HIV tested positive for two or more pathogens (p < 0.001). Patients with HIV had significantly higher proportions of fungus (20.7% vs. 3.0%, p = 0.016) and DNA virus (59.3% vs. 21.2%, p < 0.001) than those without HIV. Epstein-Barr virus (33.6%) was the most commonly identified potential pathogen in the CSF of patients living with HIV using mNGS, followed by cytomegalovirus (20.7%) and torque teno virus (13.8%). The top three causative pathogens identified in patients without HIV were Streptococcus (18.2%), Epstein-Barr virus (12.1%), and Mycobacterium tuberculosis (9.1%). In total, 113 patients living with HIV were diagnosed as having CNS infections. The rate of pathogen detection in people living with HIV with a CNS infection was significantly higher with mNGS than with conventional methods (93.8% vs. 15.0%, p < 0.001).

CONCLUSION

CSF microbiome profiles differ between patients living with and without HIV with suspected CNS infection. mNGS is a powerful tool for the diagnosis of CNS infection among people living with HIV, especially in those with mixed infections.

Clinical profile of central nervous system space-occupying lesions and their association with CD4 counts in patients with HIV: A prospective observational study

Background

Neurological manifestations are one of the major concerns for patients with human immunodeficiency virus (HIV). The secondary spectrum includes space-occupying lesions (SOL), including tuberculoma, cryptococcosis, candidiasis, toxoplasmosis, primary central nervous system lymphoma (PCNSL), and progressive multifocal leukoencephalopathy (PML).

Aim

To assess the neurological manifestations, disease outcome, and their associations with cluster of differentiation 4 (CD4) counts in patients with HIV.

Materials and Methods

This single-center, prospective, observational study was performed in the Department of General Medicine of a tertiary care institute, over a period of 2 years (January 2017 to December 2018). The study included 150 known or newly diagnosed HIV patients with CNS SOL. The physical examination, laboratory investigations, and imaging were conducted on every patient, and the findings were noted.

Results

The patients mainly presented with hemiparesis (52%), had involvement of the frontal region (38.7%), and were diagnosed with tuberculoma (29.3%). Other diagnoses were toxoplasmosis (22.7%), PML (17.3%), PCNSL (15.3%), brain abscess (10%), and neurocysticercosis (5.3%). Of 150 patients, 136 (90.7%) were survivors, while 14 (9.3%) were non-survivors. The mean CD4 count was significantly less in patients with toxoplasmosis (P < 0.0001) and PCNSL (P = 0.02), and significantly higher in patients with tuberculoma (P < 0.0001) and brain abscess (P = 0.0009) relative to other causes of SOL. Moreover, the mean CD4 count was not significantly associated with survivors and non-survivors (P = 0.28).

Conclusion

In patients with HIV, CD4 count was significantly low in toxoplasmosis and PCNSL, and high in tuberculoma and brain abscess.

Nanopore targeted sequencing-based diagnosis of central nervous system infections in HIV-infected patients

BACKGROUND

Early and accurate etiological diagnosis is very important for improving the prognosis of central nervous system (CNS) infections in human immunodeficiency virus (HIV)-infected patients. The goal is not easily achieved by conventional microbiological tests. We developed a nanopore targeted sequencing (NTS) platform and evaluated the diagnostic performance for CNS infections in HIV-infected patients, with special focus on cryptococcal meningitis (CM). We compared the CM diagnostic performance of NTS with conventional methods and cryptococcal polymerase chain reaction (PCR).

METHODS

This study included 57 hospitalized HIV-infected patients with suspected CNS infections from September 2018 to March 2022. The diagnosis established during hospitalization includes 27 cases of CM, 13 CNS tuberculosis, 5 toxoplasma encephalitis, 2 cytomegalovirus (CMV) encephalitis and 1 Varicella-zoster virus (VZV) encephalitis. The 2 cases of CMV encephalitis also have co-existing CM. Target-specific PCR amplification was used to enrich pathogen sequences before nanopore sequencing. NTS was performed on stored cerebrospinal fluid (CSF) samples and the results were compared with the diagnosis during hospitalization.

RESULTS

53 (93.0%) of the patients were male. The median CD4 cell count was 25.0 (IQR: 14.0-63.0) cells/uL. The sensitivities of CSF culture, India ink staining, cryptococcal PCR and NTS for CM were 70.4% (95%CI: 51.5 - 84.1%), 76.0% (95%CI: 56.6 - 88.5%), 77.8% (59.2 - 89.4%) and 85.2% (95%CI: 67.5 - 94.1%), respectively. All those methods had 100% specificity for CM. Our NTS platform could identify Cryptococcus at species level. Moreover, NTS was also able to identify all the 5 cases of toxoplasma encephalitis, 2 cases of CMV encephalitis and 1 VZV encephalitis. However, only 1 of 13 CNS tuberculosis cases was diagnosed by NTS, and so did Xpert MTB/RIF assay.

CONCLUSIONS

NTS has a good diagnostic performance for CM in HIV-infected patients and may have the ability of simultaneously detecting other pathogens, including mixed infections. With continuing improving of the NTS platform, it may be a promising alterative microbiological test for assisting with the diagnosis of CNS infections.

Central Nervous System Tuberculosis in Immunocompromised Patients: A Case Report Emphasizing Immune Status and Early Recognition and Treatment

Tuberculosis (TB) remains a global health challenge. Although pulmonary TB is the most frequent presentation, extrapulmonary involvement can occur, especially in immunocompromised patients. HIV-positive individuals are particularly vulnerable to opportunistic infections, such as TB, and CNS involvement is more prevalent in these patients, often leading to a poorer prognosis. CNS TB management is challenging due to nonspecific symptoms and delayed diagnosis, contributing to high mortality. It can manifest diffusely as tuberculous meningitis (TBM), localized as tuberculoma or tuberculous abscess, or as extradural and intradural spinal infections. TBM is the primary CNS manifestation, bearing significant morbidity and mortality, and rarely complicates with involvement of the spinal cord, termed tuberculous myelitis, which is associated with an unfavorable prognosis. A 61-year-old male, smoker with a history of substance abuse, undergoing seven months of antiretroviral therapy (ART) for HIV-1, presented with a two-day history of altered consciousness, sphincter incontinence, and fever. He also reported headaches, dizziness, and sleep disturbances over the past months. The examination revealed fever, asthenia, prostration, disorientation, neck rigidity, and bilateral lower limb weakness. Initial tests indicated lymphopenia, hyponatremia, and a slightly elevated C-reactive protein. Cranial CT showed no abnormalities. Lumbar puncture yielded abnormal cerebrospinal fluid (CSF), xanthochromic, hyperproteinorrheic (2316 g/L), hypoglycorrhagic (24mg/dl), with pleocytosis predominantly of mononuclear cells (98%). Compared to the values prior to ART treatment, the patient had a decreased HIV-1 viral (44 copies/ml) load but also a decreased CD4+ cell count (43 cells/mm3). Given the patient's rapid clinical deterioration, immunosuppression history, and a positive interferon-gamma release assay (IGRA) prior to ART, treatment with antituberculous drugs and dexamethasone was started at admission. Subsequently, Mycobacterium tuberculosis was identified through polymerase chain reaction (PCR) of the CSF. Cranial and spinal MRI revealed leptomeningeal enhancement from C2-C3 to the cauda equina, consistent with meningitis, without intracranial extension, and findings suggestive of myelitis, without evidence of tuberculomas or spinal cord osseous involvement. One week after treatment, the recovery of higher neurological functions became evident. Improvement in lower limb motor deficits had a delayed trajectory, with marginal progress observed at discharge. After an eight-week incubation, CSF mycobacterial culture analysis yielded negative results. This case discusses the importance of early suspicion and intervention in CNS infection prognosis. Attention to signs and symptoms beyond the most frequent ones is crucial, particularly in immunocompromised individuals like HIV patients. Identifying CSF features in different CNS infections and group-specific particulars facilitates the prompt initiation of treatment. Additionally, in co-infected patients (HIV and CNS TB), considering factors such as ART duration, CD4+ cell count, and viral load is important, in influencing the disease's incidence, course, and prognosis.

Intestinal Microbiota Dysbiosis Promotes Mucosal Barrier Damage and Immune Injury in HIV-Infected Patients

The intestinal microbiota is an "invisible organ" in the human body, with diverse components and complex interactions. Homeostasis of the intestinal microbiota plays a pivotal role in maintaining the normal physiological process and regulating immune homeostasis. By reviewing more than one hundred related studies concerning HIV infection and intestinal microbiota from 2011 to 2023, we found that human immunodeficiency virus (HIV) infection can induce intestinal microbiota dysbiosis, which not only worsens clinical symptoms but also promotes the occurrence of post-sequelae symptoms and comorbidities. In the early stage of HIV infection, the intestinal mucosal barrier is damaged and a persistent inflammatory response is induced. Mucosal barrier damage and immune injury play a pivotal role in promoting the post-sequelae symptoms caused by HIV infection. This review summarizes the relationship between dysbiosis of the intestinal microbiota and mucosal barrier damage during HIV infection and discusses the potential mechanisms of intestinal barrier damage induced by intestinal microbiota dysbiosis and inflammation. Exploring these molecular mechanisms might provide new ideas to improve the efficacy of HIV treatment and reduce the incidence of post-sequelae symptoms.

Current knowledge of the immune reconstitution inflammatory syndrome in Whipple disease: a review

Immune reconstitution inflammatory syndrome (IRIS) is characterized by exaggerated and dysregulated inflammatory responses that occur as a result of reconstitution of adaptive or innate immunity. A wide range of microorganisms have been found to be associated with IRIS, such as human immunodeficiency virus (HIV), Mycobacterium and actinobacteria. Whipple disease (WD) is an infectious disorder caused by the Gram-positive bacterium Tropheryma whipplei (T. whipplei) and IRIS also serves as a complication during its treament. Although many of these pathological mechanisms are shared with related inflammatory disorders, IRIS in WD exhibits distinct features and is poorly described in the medical literature. Novel investigations of the intestinal mucosal immune system have provided new insights into the pathogenesis of IRIS, elucidating the interplay between systemic and local immune responses. These insights may be used to identify monitoring tools for disease prevention and to develop treatment strategies. Therefore, this review synthesizes these new concepts in WD IRIS to approach the feasibility of manipulating host immunity and immune reconstitution of inflammatory syndromes from a newer, more comprehensive perspective and study hypothetical options for the management of WD IRIS.

Case report: A toxoplasmic encephalitis in an immunocompromised child detected through metagenomic next-generation sequencing

There exist numerous pathogens that are capable of causing infections within the central nervous system (CNS); however, conventional detection and analysis methods prove to be challenging. Clinical diagnosis of CNS infections often depends on clinical characteristics, cerebrospinal fluid (CSF) analysis, imaging, and molecular detection assays. Unfortunately, these methods can be both insensitive and time consuming, which can lead to missed diagnoses and catastrophic outcomes, especially in the case of infrequent diseases. Despite the application of appropriate prophylactic regimens and evidence-based antimicrobial agents, CNS infections continue to result in significant morbidity and mortality in hospital settings. Metagenomic next-generation sequencing (mNGS) is a novel tool that enables the identification of thousands of pathogens in a target-independent manner in a single run. The role of this innovative detection method in clinical pathogen diagnostics has matured over time. In this particular research, clinicians employed mNGS to investigate a suspected CNS infection in a child with leukemia, and unexpectedly detected Toxoplasma gondii.

Case

A 3-year-old child diagnosed with T-cell lymphoblastic lymphoma was admitted to our hospital due to a 2-day history of fever and headache, along with 1 day of altered consciousness. Upon admission, the patient's Glasgow Coma Scale score was 14. Brain magnetic resonance imaging revealed multiple abnormal signals. Due to the patient's atypical clinical symptoms and laboratory test results, determining the etiology and treatment plan was difficulty.Subsequently, the patient underwent next-generation sequencing examination of cerebrospinal fluid. The following day, the results indicated the presence of Toxoplasma gondii. The patient received treatment with a combination of sulfamethoxazole (SMZ) and azithromycin. After approximately 7 days, the patient's symptoms significantly improved, and they were discharged from the hospital with oral medication to continue at home. A follow-up polymerase chain reaction (PCR) testing after about 6 weeks revealed the absence of Toxoplasma.

Conclusion

This case highlights the potential of mNGS as an effective method for detecting toxoplasmic encephalitis (TE). Since mNGS can identify thousands of pathogens in a single run, it may be a promising detection method for investigating the causative pathogens of central nervous system infections with atypical features.

Cytomegalovirus (CMV)-Driven Transformation: An Uncommon Cause of a Central Nervous System Pseudotumor

Cytomegalovirus (CMV) is an opportunistic virus that can cause life-threatening neurological diseases in immunocompromised individuals, particularly those with HIV/AIDS. In this case report, a patient presenting with left gait lateralization was found to have a ring-enhancing cerebral mass lesion that was attributed to CMV. To date, only eight similar cases have been documented. When evaluating patients with HIV/AIDS who have cerebral mass lesions, clinicians should keep CMV as a possible cause because prompt antiviral therapy may improve clinical outcomes.

Brain opportunistic infections and tumors in people living with HIV - still a challenge in efficient antiretroviral therapy era

The aim of the study was to evaluate the incidence of brain opportunistic pathologies and survival in patients living with HIV from a Romanian tertiary center. A 15-year prospective observational study of brain opportunistic infections diagnosed in HIV-infected patients was performed at Victor Babes Hospital, Bucharest, between January 2006 and December 2021. Characteristics and survival were compared related to modes of HIV acquisition and type of opportunistic infection. A total of 320 patients were diagnosed with 342 brain opportunistic infections (incidence 9.79 per 1000 person-years), 60.2% males with median age at diagnosis of 31 years (IQR 25, 40). Median CD4 cell count and VL were 36/μL (IQR 14, 96) and 5.1 log10 copies/mL (IQR 4, 5.7) respectively. The routes of HIV acquisition were heterosexual (52.6%), parenteral route in early childhood (31.6%), injecting drug use (12.9%), men having sex with men (1.8%), and vertical (1.2%). The most common brain infections were progressive multifocal leukoencephalopathy (31.3%), cerebral toxoplasmosis (26.9%), tuberculous meningitis (19.3%), and cryptococcal meningitis (16.7%). Patients infected by parenteral mode in early childhood were younger at diagnosis of both opportunistic infection and HIV (p < 0.001 and p < 0.001, respectively), developed more frequently PML (p < 0.001), and had the lowest early (p = 0.002) and late (p = 0.019) mortality rates. Risk factors for shorter survival were age > 30 years (p = 0.001), injecting drug use (p = 0.003), CD4 +  < 100/μL (p = 0.007), and VL > 5 log10 copies/mL at diagnosis (p < 0.001). The incidence and mortality rate of brain opportunistic infections were high and did not decrease significantly during the study period, due to late presentation or non-adherence to ART.

Significant clinical outcome using pyrimethamine and clindamycin in cerebral toxoplasmosis with severe edema: a case report

Cerebral toxoplasmosis is a complication in HIV/AIDS patients that has recently increased in new cases due to increased HIV/AIDS incidents.

Case Presentation

An Indonesian male, 26-year old, complained of severe headache, left hemiparesis, and tremors. A brain computed tomography scan with contrast showed a large mass, extensive edema, and a significant midline shift resembling a brain tumor. The HIV test was positive, and CD4 decreased. The patient was treated with dexamethasone, mannitol, and pyrimethamine-clindamycin as therapy. After 2 weeks of treatment, the headache, hemiparesis, and tremor were clinically improved. Two months later, a brain computed tomography scan and MRI showed a good prognosis.

Clinical Discussion

The diagnosis of cerebral toxoplasmosis is based on a radiological examination and an HIV/AIDS test. Management of cerebral toxoplasmosis using pyrimethamine-clindamycin, while steroids are not recommended unless disproportionate cytotoxic edema is displayed and life-threatening.

Conclusion

A combination of pyrimethamine-clindamycin, and steroids can improve the prognosis of cerebral toxoplasmosis with severe edema.

Headache, Fever, and Myalgias in an HIV-Positive Male with a History of Tuberculosis: Epstein–Barr Virus Aseptic Meningitis

Background: We describe a case of EBV aseptic meningitis in a patient with HIV with an extensive history of prior infections and exposures. Detailed Case Description: A 35-year-old man with a history of HIV, syphilis, and partially treated tuberculosis presented with headache, fever, and myalgias. He reported recent exposure to dust from a construction site and had sexual contact with a partner with active genital lesions. An initial workup revealed mildly elevated inflammatory markers, significant pulmonary scarring from tuberculosis with a classic “weeping willow sign”, and lumbar puncture findings consistent with aseptic meningitis. An extensive evaluation was conducted to identify causes of bacterial and viral meningitis, including syphilis. Immune reconstitution inflammatory syndrome and isoniazid-induced aseptic meningitis were also considered based on his medications. EBV was ultimately isolated through PCR from the patient’s peripheral blood. The patient’s condition improved, and he was discharged on his home antiretroviral and anti-tuberculous treatment. Conclusion: Central nervous system infections represent unique challenges in patients with HIV. EBV reactivation can present with atypical symptoms and should be considered as a cause of aseptic meningitis in this population.

Metagenomic next-generation sequencing versus traditional laboratory methods for the diagnosis of central nervous system opportunistic infections in HIV-infected Chinese adults

To evaluate clinical value of metagenomic next-generation sequencing (mNGS) in people living with HIV/AIDS (PLWHA) who had CNS disorders. Cerebrospinal fluid (CSF) samples from 48 PLWHA presenting with CNS disorders were sequenced using mNGS and compared with clinical conventional diagnostic methods. In total, 36/48 ss(75%) patients were diagnosed with pathogen(s) infection by mNGS, and the positive detection proportion by mNGS was higher than that by clinical conventional diagnostic methods (75% vs 52.1%, X² = 5.441, P = 0.020). Thirteen out of 48 patients (27.1%) were detected with 3-7 pathogens by mNGS. Moreover, 77 pathogen strains were detected, of which 94.8% (73/77) by mNGS and 37.0% (30/77) by clinical conventional methods (X² = 54.206, P < 0.001). The sensitivity and specificity of pathogens detection by mNGS were 63.9% (23/36) and 66.7% (8/12), respectively, which were superior to that by clinical conventional methods (23/36 vs 9/25, X² = 4.601, P = 0.032; 8/12 vs 5/23, X² = 5.029, P = 0.009). The application of mNGS was superior for its ability to detect a variety of unknown pathogens and multiple pathogens infection, and relatively higher sensitivity and specificity in diagnosis of CNS disorders in PLWHA.

Evaluation of Specific Cellular and Humoral Immune Response to Toxoplasma gondii in Patients with Autoimmune Rheumatic Diseases Immunomodulated Due to the Use of TNF Blockers

(1) Background: TNF antagonists have been used to treat autoimmune diseases (AD). However, during the chronic phase of toxoplasmosis, TNF-α and TNFR play a significant role in maintaining disease resistance and latency. Several studies have demonstrated the risk of latent infections’ reactivation in patients infected with toxoplasmosis. Our objective was to verify whether patients with autoimmune rheumatic diseases, who use TNF antagonists and/or synthetic drugs and had previous contact with Toxoplasma gondii (IgG+), present any indication of an increased risk of toxoplasmosis reactivation. (2) Methods: Blood samples were collected, and peripheral blood mononuclear cells (PBMCs) were evaluated after stimulation with antigens of Toxoplasma gondii, with anti-CD3/anti-CD28 or without stimulus, at 48 and 96 h. CD69+, CD28+, and PD-1 stains were evaluated, in addition to intracellular expression of IFN-γ, IL-17, and IL-10 by CD4+ and the presence of regulatory CD4+ T cells by labeling CD25+, FOXP3, and LAP. The cytokines IL-2, IL-4, IL-6, IL-10, IFN-γ, TNF-α, and IL-17 were measured in the culture supernatant after 96 h. Serology for IgG and IgG1 was evaluated. (3) Results: There were no differences in the levels of IgG and IgG1 between the groups, but the IgG1 avidity was reduced in the immunobiological group compared to the control group. All groups exhibited a significant correlation between IgG and IgG1 positivity. CD4+ T lymphocytes expressing PD-1 were increased in individuals suffering from autoimmune rheumatic diseases and using disease-modifying antirheumatic drugs. In addition, treatment with TNF blockers did not seem to influence the populations of regulatory T cells and did not interfere with the expression of the cytokines IFN-γ, IL-17, and IL-10 by CD4+ cells or the production of cytokines by PBMCs from patients with AD. (4) Conclusions: This study presents evidence that the use of TNF-α blockers did not promote an immunological imbalance to the extent of impairing the anti-Toxoplasma gondii immune response and predisposing to toxoplasmosis reactivation.

Efficacy and safety of lenalidomide in HIV-associated cryptococcal meningitis patients with persistent intracranial inflammation: an open-label, single-arm, prospective interventional study

BACKGROUND

Patients with human immunodeficiency virus-associated cryptococcal meningitis (HIV-CM) have persistent intracranial inflammation despite negative cerebrospinal fluid (CSF) fungal cultures after optimal treatment for CM, which could be devastating for the central nervous system. However, a definitive treatment strategy for persistent intracranial inflammation despite optimal antifungal therapies is undefined.

METHODS

We identified 14 HIV-CM patients with persistent intracranial inflammation and conducted a 24-week, prospective, interventional study. All participants received lenalidomide (25 mg, p.o.) on days 1 to 21 of a 28-day cycle. Follow-up lasted for 24 weeks with visits at baseline and weeks 4, 8, 12, and 24. The primary endpoint was the change in clinical manifestations, routine CSF parameters, and MRI findings after lenalidomide treatment. An exploratory analysis was made on changes in cytokine levels in CSF. Safety and efficacy analyses were undertaken in patients who received at least one dose of lenalidomide.

RESULTS

Of 14 participants, 11 patients completed the 24 weeks of follow-up. Rapid clinical remission following lenalidomide therapy was observed. Clinical manifestations (fever, headache, altered mentation) were reversed fully by week-4 and remained stable during follow-up. A significant reduction in white blood cell (WBC) count in CSF was noted occurred at week-4 (P = 0.009). The median protein concentration in CSF decreased from 1.4 (0.7-3.2) g/L at baseline to 0.9 (0.6-1.4) at week-4 (P = 0.004). The median albumin concentration in CSF decreased from 79.2 (48.4-149.8) mg/L at baseline to 55.3 (38.3-89.0) mg/L at week-4 (P = 0.011). The WBC count, protein level, and albumin level in CSF remained stable and approached a normal range through week-24. There was no significant change in immunoglobulin-G, intracranial pressure (ICP), or chloride-ion concentration at each visit. Brain MRI demonstrated multiple lesions to be absorbed post-therapy. Levels of tumor necrosis factor-α granulocyte colony stimulating factor, interleukin (IL)-6, and IL-17A decreased significantly during 24-week follow-up. Two (14.3%) patients had mild skin rash, which resolved spontaneously. Lenalidomide-related serious adverse events were not observed.

CONCLUSION

Lenalidomide could improve persistent intracranial inflammation in HIV-CM patients significantly and was well tolerated without serious adverse events observed. And the additional randomized controlled study is required to further validate the finding.

Reviewing the Potential Links between Viral Infections and TDP-43 Proteinopathies

Transactive response DNA binding protein 43 kDa (TDP-43) was discovered in 2001 as a cellular factor capable to inhibit HIV-1 gene expression. Successively, it was brought to new life as the most prevalent RNA-binding protein involved in several neurological disorders, such as amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD). Despite the fact that these two research areas could be considered very distant from each other, in recent years an increasing number of publications pointed out the existence of a potentially important connection. Indeed, the ability of TDP-43 to act as an important regulator of all aspects of RNA metabolism makes this protein also a critical factor during expression of viral RNAs. Here, we summarize all recent observations regarding the involvement of TDP-43 in viral entry, replication and latency in several viruses that include enteroviruses (EVs), Theiler's murine encephalomyelitis virus (TMEV), human immunodeficiency virus (HIV), human endogenous retroviruses (HERVs), hepatitis B virus (HBV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), West Nile virus (WNV), and herpes simplex virus-2 (HSV). In particular, in this work, we aimed to highlight the presence of similarities with the most commonly studied TDP-43 related neuronal dysfunctions.

Mechanism of extracellular space changes in cryptococcal brain granuloma revealed by MRI tracer

Purpose

This study aimed to investigate the changes in extracellular space (ECS) in cryptococcal brain granuloma and its pathological mechanism.

Materials and methods

The animal model of cryptococcal brain granuloma was established by injecting 1 × 10⁶ CFU/ml of Cryptococcus neoformans type A suspension into the caudate nucleus of Sprague-Dawley rats with stereotactic technology. The infection in the brain was observed by conventional MRI scanning on days 14, 21, and 28 of modeling. The tracer-based MRI with a gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA) as a magnetic tracer was performed on the rats with cryptococcal granuloma and the rats in the control group. The parameters of ECS in each area of cryptococcal brain granuloma were measured. The parameters of ECS in the two groups were compared by independent sample t-test, and the changes in ECS and its mechanism were analyzed.

Results

Up to 28 days of modeling, the success rate of establishing the brain cryptococcal granuloma model with 1 × 10⁶ CFU/ml Cryptococcus neoformans suspension was 60%. In the internal area of cryptococcal granuloma, the effective diffusion coefficient D* was significantly higher than that of the control group (t = 2.76, P < 0.05), and the same trend showed in the volume ratio α (t = 3.71, P < 0.05), the clearance rate constant k (t = 3.137, P < 0.05), and the tracer half-life T_1/2 (t = 3.837, P < 0.05). The tortuosity λ decreased compared with the control group (t = -2.70, P < 0.05). At the edge of the cryptococcal granuloma, the D* and α decreased, while the λ increased compared with the control group (D*:t = -6.05, P < 0.05; α: t = -4.988, P < 0.05; λ: t = 6.222, P < 0.05).

Conclusion

The internal area of the lesion demonstrated a quicker, broader, and more extended distribution of the tracer, while the edge of the lesion exhibited a slower and narrower distribution. MRI tracer method can monitor morphological and functional changes of ECS in pathological conditions and provide a theoretical basis for the treatment via ECS.

Keeping T cell memories in mind

The mammalian central nervous system (CNS) contains a vibrant community of resident adaptive immune cells at homeostasis. Among these are memory CD8+ and CD4+ T cells, which reside in the CNS in the settings of health, aging, and neurological disease. These T cells commonly exhibit a tissue-resident memory (TRM) phenotype, suggesting that they are antigen-experienced and remain separate from the circulation. Despite these characterizations, T cell surveillance of the CNS has only recently been studied through the lens of TRM immunology. In this Review, we outline emerging concepts of CNS TRM generation, localization, maintenance, function, and specificity. In this way, we hope to highlight roles of CNS TRM in health and disease to inform future studies of adaptive neuroimmunity.

Metagenomic next-generation sequencing for identification of central nervous system pathogens in HIV-infected patients

Although considerable interest in metagenomic next-generation sequencing (mNGS) has been attracted in recent years, limited data are available regarding the performance of mNGS in HIV-associated central nervous system (CNS) infection. Here, we conducted a retrospectively analyzing of the cerebrospinal fluid (CSF) mNGS reports and other clinical data from 80 HIV-infected patients admitted to the Second Hospital of Nanjing, China from March, 2018 to March, 2022. In our study, CSF mNGS reported negative result, mono-infection, and mixed infection in 8.8, 36.2, and 55% of the patients, respectively. Epstein-Barr virus (EBV), positive in 52.5% of samples, was the most commonly reported pathogen, followed by cytomegalovirus (CMV), John Cunningham virus (JCV), torque teno virus (TTV), cryptococcus neoformans (CN), toxoplasma Gondii (TE), and mycobacterium tuberculosis (MTB). 76.2% of the EBV identification and 54.2% of the CMV identification were not considered clinically important, and relative less sequence reads were reported in the clinical unimportant identifications. The clinical importance of the presence of TTV in CSF was not clear. Detection of JCV, CN, or TE was 100% suggestive of specific CNS infection, however, 60% of the MTB reports were considered contamination. Moreover, of the 44 (55%) mixed infections reported by mNGS, only 4 (5%) were considered clinical important, and mNGS failed to identify one mixed infection. Additionally, except for MTB, CSF mNGS tended to have high sensitivity to identify the above-mentioned pathogens (almost with 100% sensitivity). Even all the diagnostic strategies were evaluated, the cause of neurological symptoms remained undetermined in 6 (7.5%) patients. Overall, our results suggest that mNGS is a very sensitive tool for detecting common opportunistic CNS pathogen in HIV-infected patients, although its performance in CNS tuberculosis is unsatisfactory. EBV and CMV are commonly detected by CSF mNGS, however, the threshold of a clinical important detection remains to be defined.

CD8 Encephalitis: A Diagnostic Dilemma

CD8+ encephalitis is a subacute encephalopathy associated with HIV infection. Pathophysiology is thought to be auto-reactive CD8+ cells attacking on HIV infected CD4+ cells and ‘viral escape’ phenomena (replication of CD8+ cells in CSF). We present a case of a 45-year-old man with well controlled HIV who developed CD8 encephalitis following Herpes simplex encephalitis. He had persistent encephalopathy for several weeks with status epilepticus and agitated delirium, and diagnosis remained elusive until a brain biopsy confirmed the diagnosis.

Single-cell sequencing resolves the landscape of immune cells and regulatory mechanisms in HIV-infected immune non-responders

Immune non-responder after highly active antiretroviral therapy (HAART) is the main cause of opportunistic infections and high mortality in AIDS patients, but the mechanism underlying immune reconstitution failure is poorly understood. Here, we performed scRNA-seq, and scATAC-seq analysis of peripheral blood mononuclear cells (PBMCs) derived from immune non-responder (INR) and responder (IR) HIV-1-infected subjects. We found low expression of mucosal-associated invariant T (MAIT) cells in INRs, which exhibited transcriptional profiles associated with impaired mitochondrial function and apoptosis signaling. Single-cell assays for transposase-accessible chromatin (scATAC-seq) and flow cytometry revealed diminished mitochondrial fitness in MAIT cells from INRs, and MAIT had low expression of transcription factor A for mitochondria (TFAM) and peroxisomal proliferator-activated receptor alpha (PPARA). These findings demonstrate that restoring mitochondrial function could modulate the immune dysfunction characteristic of MAIT against bacterial co-infections in INRs subjects.

Differentiating central nervous system infection from disease infiltration in hematological malignancy

Hematological malignancies place individuals at risk of CNS involvement from their hematological disease and opportunistic intracranial infection secondary to disease-/treatment-associated immunosuppression. Differentiating CNS infection from hematological disease infiltration in these patients is valuable but often challenging. We sought to determine if statistical models might aid discrimination between these processes. Neuroradiology, clinical and laboratory data for patients with hematological malignancy at our institution between 2007 and 2017 were retrieved. MRI were deep-phenotyped across anatomical distribution, presence of pathological enhancement, diffusion restriction and hemorrhage and statistically modelled with Bayesian-directed probability networks and multivariate logistic regression. 109 patients were studied. Irrespective of a diagnosis of CNS infection or hematological disease, the commonest anatomical distributions of abnormality were multifocal-parenchymal (34.9%), focal-parenchymal (29.4%) and leptomeningeal (11.9%). Pathological enhancement was the most frequently observed abnormality (46.8%), followed by hemorrhage (22.9%) and restricted diffusion (19.3%). Logistic regression could differentiate CNS infection from hematological disease infiltration with an AUC of 0.85 where, with OR > 1 favoring CNS infection and < 1 favoring CNS hematological disease, significantly predictive imaging features were hemorrhage (OR 24.61, p = 0.02), pathological enhancement (OR 0.17, p = 0.04) and an extra-axial location (OR 0.06, p = 0.05). In conclusion, CNS infection and hematological disease are heterogeneous entities with overlapping radiological appearances but a multivariate interaction of MR imaging features may assist in distinguishing them.

Differential Expression of miRNA-192 is a Potential Biomarker for HIV Associated Immune Recovery Uveitis

PURPOSE

Notwithstanding well-established clinical features of Immune Recovery Uveitis (IRU), specific diagnostic tools to identify at-risk patients are lacking. Identification of biomarkers for IRU prediction can allow high-risk patients to benefit from specific preventive strategies, development of therapies, and elucidate immune reconstitution associated pathogenesis.

METHODS

HIV+ patients were classified into four groups (A, B, C and D) with and without ocular manifestations, with follow-up over a year. Patients' ocular parameters were examined and manifestations like uveitis and IRU noted. Selected miRNAs were investigated in PBMCs by using miRNA PCR assay. Bioinformatic analysis used miRNet to predict the targets of miRNA-192-5p and miRNA-543 and KOBAS for pathways.

RESULTS

Hsa-miR-192-5p and hsa-miR-543 levels were measured by qPCR using RNA isolated from PBMCs of HIVinfected patients. Hsa-miR-192-5p and hsa-miR-543 were down regulated in patients exhibiting ocular manifestations. Our results showed hsa-miR-192-5p (Group B vs D p 0.007) and hsa-miR-543 levels in PBMCs reliably distinguish between HIV patients diagnosed with IRU. Both miRNAs target multiple genes involved in inflammatory pathways as predicted by bioinformatic analysis.

CONCLUSION

Decreased expression levels of miRNA-192 in patients with ocular manifestations and IRU, could facilitate identification of the status of the disease in HIV patients.

Progressive multifocal leukoencephalopathy associated with chemotherapy induced lymphocytopenia in solid tumors – case report of an underestimated complication

Background

JC virus reactivation causing progressive multifocal leukoencephalopathy (PML) occurs preferentially in human immunodeficiency virus (HIV) positive individuals or patients suffering from hematologic neoplasms due to impaired viral control. Reactivation in patients suffering from solid malignancies is rarely described in published literature.

Case Presentation

Here we describe a case of PML in a male patient suffering from esophageal cancer who underwent neoadjuvant radiochemotherapy and surgical resection in curative intent resulting in complete tumor remission. The radiochemotherapy regimen contained carboplatin and paclitaxel (CROSS protocol). Since therapy onset, the patient presented with persistent and progredient leukopenia and lymphopenia in absence of otherwise known risk factors for PML. Symptom onset, which comprised aphasia, word finding disorder, and paresis, was apparent 7 months after therapy initiation. There was no relief in symptoms despite standard of care PML directed supportive therapy. The patient died two months after therapy onset.

Conclusion

PML is a very rare event in solid tumors without obvious states of immununosuppression and thus harbors the risk of unawareness. The reported patient suffered from lymphopenia, associated with systemic therapy, but was an otherwise immunocompetent individual. In case of neurologic impairment in patients suffering from leukopenia, PML must be considered – even in the absence of hematologic neoplasia or HIV infection.

Restriction Checkpoint Controls Bradyzoite Development in Toxoplasma gondii

Human toxoplasmosis is a life-threatening disease caused by the apicomplexan parasite Toxoplasma gondii. Rapid replication of the tachyzoite is associated with symptomatic disease, while suppressed division of the bradyzoite is responsible for chronic disease. Here, we identified the T. gondii cell cycle mechanism, the G1 restriction checkpoint (R-point), that operates the switch between parasite growth and differentiation. Apicomplexans lack conventional R-point regulators, suggesting adaptation of alternative factors. We showed that Cdk-related G1 kinase TgCrk2 forms alternative complexes with atypical cyclins (TgCycP1, TgCycP2, and TgCyc5) in the rapidly dividing developmentally incompetent RH and slower dividing developmentally competent ME49 tachyzoites and bradyzoites. Examination of cyclins verified the correlation of cyclin expression with growth dependence and development capacity of RH and ME49 strains. We demonstrated that rapidly dividing RH tachyzoites were dependent on TgCycP1 expression, which interfered with bradyzoite differentiation. Using the conditional knockdown model, we established that TgCycP2 regulated G1 duration in the developmentally competent ME49 tachyzoites but not in the developmentally incompetent RH tachyzoites. We tested the functions of TgCycP2 and TgCyc5 in alkaline induced and spontaneous bradyzoite differentiation (rat embryonic brain cells) models. Based on functional and global gene expression analyses, we determined that TgCycP2 also regulated bradyzoite replication, while signal-induced TgCyc5 was critical for efficient tissue cyst maturation. In conclusion, we identified the central machinery of the T. gondii restriction checkpoint comprised of TgCrk2 kinase and three atypical T. gondii cyclins and demonstrated the independent roles of TgCycP1, TgCycP2, and TgCyc5 in parasite growth and development. IMPORTANCE Toxoplasma gondii is a virulent and abundant human pathogen that puts millions of silently infected people at risk of reactivation of the chronic disease. Encysted bradyzoites formed during the chronic stage are resistant to current therapies. Therefore, insights into the mechanism of tissue cyst formation and reactivation are major areas of investigation. The fact that rapidly dividing parasites differentiate poorly strongly suggests that there is a threshold of replication rate that must be crossed to be considered for differentiation. We discovered a cell cycle mechanism that controls the T. gondii growth-rest switch involved in the conversion of dividing tachyzoites into largely quiescent bradyzoites. This switch operates the T. gondii restriction checkpoint using a set of atypical and parasite-specific regulators. Importantly, the novel T. gondii R-point network was not present in the parasite's human and animal hosts, offering a wealth of new and parasite-specific drug targets to explore in the future.

Effect of Cytomegalovirus Infection on the Central Nervous System: Implications for Psychiatric Disorders

Cytomegalovirus (CMV) is a common herpesvirus that establishes lifelong latent infections and interacts extensively with the host immune system, potentially contributing to immune activation and inflammation. Given its proclivity for infecting the brain and its reactivation by inflammatory stimuli, CMV is well known for causing central nervous system complications in the immune-naïve (e.g., in utero) and in the immunocompromised (e.g., in neonates, individuals receiving transplants or cancer chemotherapy, or people living with HIV). However, its potentially pathogenic role in diseases that are characterized by more subtle immune dysregulation and inflammation such as psychiatric disorders is still a matter of debate. In this chapter, we briefly summarize the pathogenic role of CMV in immune-naïve and immunocompromised populations and then review the evidence (i.e., epidemiological studies, serological studies, postmortem studies, and recent neuroimaging studies) for a link between CMV infection and psychiatric disorders with a focus on mood disorders and schizophrenia. Finally, we discuss the potential mechanisms through which CMV may cause CNS dysfunction in the context of mental disorders and conclude with a summary of the current state of play as well as potential future research directions in this area.

[The phenomenon of pseudotumorous cross immunohistochemical reactivity of glia in progressive multifocal leukoencephalopathy]

Progressive multifocal leukoencephalopathy (PML) is a subacute demyelinating brain damage caused by infection of oligodendrocytes and astrocytes with the lytic JC virus on the background of immunosuppression. A case report of PML with a tumor-like course is presented. Morphological diagnostics revealed non-specific staining of antibodies to Ki-67, p53, IDH1, NF and Vim in the nuclei of gliocytes affected by the JC virus. Histological examination and microscopic evaluation of the changes in the brain for the diagnosis of PML is a priority. The recommended intravital biopsy does not always help in clear verification of PML due to the limited volume of tissue fragments presented for research. For the correct interpretation of changes during an intravital pathological examination and verification of PML, it is important to take material during a stereotaxic biopsy, not only from the center, but from the edges and perifocal zone of the altered tissues for the possibility of a spatial histological assessment of the pathological process.

Misdiagnosis of HIV With Toxoplasmosis Encephalopathy With Progressive Memory Loss as the Initial Symptom: A Case Report

Toxoplasmosis encephalopathy (TE) is a kind of encephalopathy parasitic disease caused by Toxoplasma gondii. It is the most common opportunistic for central system infection in patients with acquired immunodeficiency syndrome (AIDS) or human immunodeficiency virus. Without early diagnosis and proper treatment, this opportunistic infection can be life-threatening. The common clinical manifestations of the disease include altered mental state, epilepsy, cranial nerve damage, paresthesia, cerebellar signs, meningitis, motor disorders, and neuropsychiatry. The most common presentation in about 75% of cases is a subacute episode of focal neurological abnormalities such as hemiplegia, personality changes, or aphasia. Imaging needs to be differentiated from multiple sclerosis, lymphoma, and metastases. We report a case of acquired immune deficiency syndrome complicated with toxoplasma encephalopathy with rapid progressive memory loss as the initial symptom and misdiagnosed as multiple sclerosis. Through the comprehensive analysis of the clinical symptoms and imaging examination of this disease, we hope to enhance the confidence of clinicians in the diagnosis of this disease.

Spatial-temporal analysis of HIV/AIDS and syphilis in mainland China from 2007 to 2017

Human immune deficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) and syphilis are the most common sexually transmitted diseases (STDs) worldwide, as well as in China. The objective of this study is to describe the trend of spatial and temporal variation of HIV/AIDS and syphilis in mainland China from 2007 to 2017. Stratified analysis was conducted according to age and the GDP per capita. Estimated Annual Percentage Change (EAPC) was calculated and spatial autocorrelation analysis was used to evaluate the epidemiology and identify clusters. The morbidity of new HIV infection increased from 2.5034/100 000 in 2007 to 6.9247/100 000 in 2017, with an EAPC of 9.84 (95% confidence interval [CI]: 9.07-10.60). From 2007 to 2017, the morbidity of syphilis presented a significant upward trend from 15.8834/100 000 to 34.4867/100 000 (EAPC = 6.48, 95% CI: 4.23-8.73). The number of new HIV infections (205 084) and syphilis (921 279) were highest in the 20-30 years old group, where the incidence decreased with age over 20 years. In general, HIV and syphilis infection had the same incidence trend according to age and time stratification. The morbidity of new HIV infection was mainly reported from Xinjiang and southwestern China. As for syphilis, the highest was found in Zhejiang in Xinjiang and southeast coastal areas. Both HIV and syphilis infection showed a nonrandom positive correlation by Moran's I value. The High-High cluster areas of HIV infection were concentrated in southwestern and eastern China due to syphilis. A highly significant positive correlation was found between gross domestic product per capita and syphilis infection (p < 0.05) but was not associated with HIV infection. The incidence of AIDS/HIV and syphilis is increasing year by year, and a higher prevalence is found in younger individuals. More attention should be paid to HIV infection in the southwest, syphilis in southeast coastal areas, and both the two diseases in Xinjiang.

Contamination of Soil, Water, Fresh Produce, and Bivalve Mollusks with Toxoplasma gondii Oocysts: A Systematic Review

Toxoplasma gondii is a major foodborne pathogen capable of infecting all warm-blooded animals, including humans. Although oocyst-associated toxoplasmosis outbreaks have been documented, the relevance of the environmental transmission route remains poorly investigated. Thus, we carried out an extensive systematic review on T. gondii oocyst contamination of soil, water, fresh produce, and mollusk bivalves, following the PRISMA guidelines. Studies published up to the end of 2020 were searched for in public databases and screened. The reference sections of the selected articles were examined to identify additional studies. A total of 102 out of 3201 articles were selected: 34 articles focused on soil, 40 focused on water, 23 focused on fresh produce (vegetables/fruits), and 21 focused on bivalve mollusks. Toxoplasma gondii oocysts were found in all matrices worldwide, with detection rates ranging from 0.09% (1/1109) to 100% (8/8) using bioassay or PCR-based detection methods. There was a high heterogeneity (I2 = 98.9%), which was influenced by both the sampling strategy (e.g., sampling site and sample type, sample composition, sample origin, season, number of samples, cat presence) and methodology (recovery and detection methods). Harmonized approaches are needed for the detection of T. gondii in different environmental matrices in order to obtain robust and comparable results.

Early Antiretroviral Therapy in AIDS Patients Presenting With Toxoplasma gondii Encephalitis Is Associated With More Sequelae but Not Increased Mortality

Background

Evidence on the optimal time to initiate antiretroviral therapy (ART) in the presence of toxoplasmic encephalitis (TE) is scarce. We compared the impact of early vs. delayed ART initiation on mortality and neurologic complications at discharge in a Brazilian population co-infected with HIV and TE.

Methods

We retrospectively evaluated data from 9 years of hospitalizations at a referral center in Manaus, Amazonas. All ART-naïve hospitalized patients were divided into early initiation treatment (EIT) (0-4 weeks) and delayed initiation treatment (DIT) (>4 weeks). The groups were compared using chi-square test and mortality at 16 weeks.

Results

Four hundred sixty nine patients were included, of whom 357 (76.1%) belonged to the EIT group. The median CD4⁺ lymphocyte count and CD4⁺/CD8⁺ ratio were 53 cells/mm³ and 0.09, respectively. Mortality rate and presence of sequelae were 4.9% (n = 23) and 41.6% (n = 195), respectively. Mortality was similar between groups (p = 0.18), although the EIT group had the highest prevalence of sequelae at discharge (p = 0.04). The hazard ratio for death at 16 weeks with DIT was 2.3 (p = 0.18). The necessity for intensive care unit admission, mechanical ventilation, and cardiopulmonary resuscitation were similar between groups.

Conclusion

In patients with AIDS and TE, early ART initiation might have a detrimental influence on the occurrence of sequelae.

Analysis of Deaths among HIV-Infected Patients Hospitalized in 2009–2018 in Main Centre of Infectious Disease in Region of Lower Silesia in Poland, Detailing Lesions in the Central Nervous System

Background and Objectives: Patients living with HIV (PLWH), especially those diagnosed too late or not receiving treatment with antiretroviral drugs in the stage of advanced immunodeficiency AIDS for various reasons, develop additional opportunistic infections or AIDS-defining diseases that may contribute directly to the death of these patients. Material and Methods: In this work, we focused on disorders of the central nervous system (CNS) by retrospectively analyzing the symptoms, clinical and autopsy diagnoses of patients diagnosed with HIV infection who died in the provincial specialist hospital in the Lower Silesia region in Poland. Results: The autopsy was performed in 27.4% cases. The cause of death was determined to be HIV-related/AIDS-associated in 78% patients. The most common AIDS-defining CNS diseases in our cohort were toxoplasmosis and cryptococcosis. Conslusions: The presented results of the most common causes of changes in the central nervous system among deceased HIV-infected patients are comparable to the results of studies by other scientists cited in the publication.

Spectrum of central nervous system infections in a tertiary health care centre in Cameroon

Background

Central nervous system (CNS) infections are serious and debilitating diseases with significant mortality, and high prevalence in the context of human immunodeficiency virus (HIV) pandemic in Africa. However, their diagnosis remains challenging due to outdated technical platform. We aimed to determine the frequency of CNS infection and to describe the epidemiological, clinical and outcome of this at the Douala General Hospital (DGH), Cameroon. To carry out this study, we collected the medical records of patients hospitalized for CNS infections in the internal medicine department of DGH from January 2015 to December 2019.

Results

Among 8430 files reviewed, 336 cases of CNS infection were identified giving a frequency of CNS infection of 3.99% among which 204 files were included in the study (54.4% were male). HIV infection was found in 147 patients (72.1%) with 38.1% (n = 56) of them on regular follow-up. The most common clinical signs were fever (84.8%), headache (68.6%), meningeal syndrome (38.7%), and seizures (36.3%). Cerebral toxoplasmosis (24.5%), cryptococcal meningitis (21.1%), and acute bacterial meningitis (8.3%) were leading aetiologies. Of the 143 CSF samples, 70.6% (n = 101) were sterile. The in-hospital mortality rate was 23.5% with CNS infection of unknown cause (22.1%) be independently associated to this [OR = 2.24; 95% CI 1.04–4.80, p = 0.039].

Conclusion

Clinical presentations of CNS infections are same with classical data. HIV-related opportunistic infections are the main aetiologies. About one over four patients with CNS died. Two thirds of CSF are sterile using basic laboratory assessment giving a need to identify simple tests to increase sensibility and specificity of diagnostic tools in our setting.

A Toxoplasma gondii Oxopurine Transporter Binds Nucleobases and Nucleosides Using Different Binding Modes

Toxoplasma gondii is unable to synthesize purines de novo, instead salvages them from its environment, inside the host cell, for which they need high affinity carriers. Here, we report the expression of a T. gondii Equilibrative Nucleoside Transporter, Tg244440, in a Trypanosoma brucei strain from which nucleobase transporters have been deleted. Tg244440 transported hypoxanthine and guanine with similar affinity (K_m ~1 µM), while inosine and guanosine displayed K_i values of 4.05 and 3.30 µM, respectively. Low affinity was observed for adenosine, adenine, and pyrimidines, classifying Tg244440 as a high affinity oxopurine transporter. Purine analogues were used to probe the substrate-transporter binding interactions, culminating in quantitative models showing different binding modes for oxopurine bases, oxopurine nucleosides, and adenosine. Hypoxanthine and guanine interacted through protonated N1 and N9, and through unprotonated N3 and N7 of the purine ring, whereas inosine and guanosine mostly employed the ribose hydroxy groups for binding, in addition to N1H of the nucleobase. Conversely, the ribose moiety of adenosine barely made any contribution to binding. Tg244440 is the first gene identified to encode a high affinity oxopurine transporter in T. gondii and, to the best of our knowledge, the first purine transporter to employ different binding modes for nucleosides and nucleobases.

Innovative therapeutic concepts of progressive multifocal leukoencephalopathy

Progressive multifocal leukoencephalopathy (PML) is an opportunistic viral disease of the brain-caused by human polyomavirus 2. It affects patients whose immune system is compromised by a corresponding underlying disease or by drugs. Patients with an underlying lymphoproliferative disease have the worst prognosis with a mortality rate of up to 90%. Several therapeutic strategies have been proposed but failed to show any benefit so far. Therefore, the primary therapeutic strategy aims to reconstitute the impaired immune system to generate an effective endogenous antiviral response. Recently, anti-PD-1 antibodies and application of allogeneic virus-specific T cells demonstrated promising effects on the outcome in individual PML patients. This article aims to provide a detailed overview of the literature with a focus on these two treatment approaches.

Ocular toxoplasmosis, an overview focusing on clinical aspects

Toxoplasma gondii is a widespread protozoan parasite infecting approximately one third of the world population. After proliferation of tachyzoites during the acute stage, the parasite forms tissue cysts in various anatomical sites and establishes chronic infection. Nowadays the nature of the interplay between the protozoan and its human host remains elusive. This is clearly evident in ocular toxoplasmosis, in which the parasite establishes an ambivalent relationship with the eye, manipulating the immune response and inducing variable initial lesions and further relapses. This review will focus on epidemiology and environmental, parasite and host related risk factors, clinical manifestations and laboratory findings, treatment and prophylaxis approaches in ocular toxoplasmosis. An image collection of patients referred to the Unit of Ophthalmology of Pisa's Hospital will be presented, too.

Worldwide Occurrence of HIV-Associated Neurocognitive Disorders and Its Associated Factors: A Systematic Review and Meta-Analysis

BACKGROUND

HIV-associated neurocognitive disorders are common in people living with HIV/AIDS and affect the adherence of patients to prescriptions, activities of daily living, and quality of life of patients. However, there is a lack of summative evidence in the area. The present meta-analysis was therefore addressing this gap.

METHODS

We did our electronic search in Psych-Info, EMBASE, Scopus, and PubMed. The retrieved articles were stored with the endnote reference manager and data was extracted using Meta-XL version 5.3. The quality of studies was evaluated with the modified Newcastle-Ottawa Scale (NOS). A random-effect model and STATA-16 were used to compute the average estimate of HAND. Heterogeneity was weighed with I² statistics. A sensitivity analysis and subgroup analysis were employed. The existence/nonexistence of a publication bias was checked with the Eggers test of publication bias.

RESULTS

The average prevalence of HAND was 50.41% (95% CI: 45.56, 55.26). The average estimate of HAND in Europe was found to be 50.015% whereas in Africa, Asia, and the United States of America (USA) it was 49.566, 52.032, and 50.407% respectively. The prevalence of HAND in studies that used the HIV Dementia Scale (IHDS) was 36.883% and 59.956% at cutoff points of IHDS <9.5 and IHDS <10 respectively. Besides, the estimated average of HAND with the global dementia scale (GDS) was 40.766%. The prevalence of HAND in cross-sectional, cohort, and case-control studies was 49.52, 54.087, and 44.45% in that order. Socio-demographic variables; low level of education and older age, clinical and HIV related variables; the advanced stage of the illness and CD4 count of 500 cells/dl or less and psychological variables such as comorbidity of depression increases the risk of HAND.

CONCLUSION

The prevalence of HIV-associated neurocognitive disorders was about 50.41%. Low level of education and older age, clinical and HIV related variables such as the advanced stage of the illness and CD4 count of 500 cells/dl or less, and comorbidity of depression were associated with HIV associated neurocognitive disorders. Public health interventions for HIV patients should target these essential problems.

Minimally Invasive Tissue Sampling: A Tool to Guide Efforts to Reduce AIDS-Related Mortality in Resource-Limited Settings

BACKGROUND

Available information on the causes of death among people living with human immunodeficiency virus (PLHIV) in low- and middle-income countries (LMICs) remains scarce. We aimed to provide data on causes of death in PLHIV from two LMICs, Brazil and Mozambique, to assess the impact of clinical misdiagnosis on mortality rates and to evaluate the accuracy of minimally invasive tissue sampling (MITS) in determining the cause of death in PLHIV.

METHODS

We performed coupled MITS and complete autopsy on 164 deceased PLHIV (18 children, 36 maternal deaths, and 110 adults). HIV antibody levels and HIV RNA viral loads were determined from postmortem serum samples.

RESULTS

Tuberculosis (22.7%), toxoplasmosis (13.9%), bacterial infections (13.9%), and cryptococcosis (10.9%) were the leading causes of death in adults. In maternal deaths, tuberculosis (13.9%), bacterial infections (13.9%), cryptococcosis (11.1%), and cerebral malaria (8.3%) were the most frequent infections, whereas viral infections, particularly cytomegalovirus (38.9%), bacterial infections (27.8%), pneumocystosis (11.1%), and HIV-associated malignant neoplasms (11.1%) were the leading cause among children. Agreement between the MITS and the complete autopsy was 100% in children, 91% in adults, and 78% in maternal deaths. The MITS correctly identified the microorganism causing death in 89% of cases.

CONCLUSIONS

Postmortem studies provide highly granular data on the causes of death in PLHIV. The inaccuracy of clinical diagnosis may play a significant role in the high mortality rates observed among PLHIV in LMICs. MITS might be helpful in monitoring the causes of death in PLHIV and in highlighting the gaps in the management of the infections.

High-dose rifampicin for the treatment of tuberculous meningitis: a meta-analysis of randomized controlled trials

WHAT IS KNOWN AND OBJECTIVE

Tuberculous meningitis (TBM) is one of the most serious types of extrapulmonary tuberculosis and has caused distress to human. Effective treatment is particularly important. The aim of this meta-analysis is to compare the efficacy of high-dose and standard-dose rifampicin.

METHODS

Databases including PubMed, Web of Science, Embase, Scopus and the Cochrane Library databases were electronically searched to identify randomized controlled trials that reported high-dose rifampicin in treatment of patients with TBM. The retrieval time is limited from inception to June 2021. Two reviewers independently screened literature, extracted data and assessed risk bias of included studies. Meta-analysis was performed by using STATA 12.0 software.

RESULTS AND DISCUSSION

A total of 12 studies involving 1596 patients were included. The meta-analysis results showed no significant differences in 6-month mortality, 9-month mortality, Grade I-II AE, Grade III-V AE, hepatotoxicity, hepatotoxicity Grade I-II and cardiologic events between high-dose rifampicin (or high-dose rifampicin plus moxifloxacin or levofloxacin) and standard-dose groups. The log(C_max ) (WMD 0.69, 95%CI 0.59-0.79, p 0.001) and log(AUC_0-24h ) (WMD 0.79, 95%CI 0.71-0.88, p 0.001) were higher with high-dose rifampicin. Subgroup analysis revealed the rise of log(C_max ) in high-dose rifampicin orally was consistent with intravenous administration compared with the control (WMD 0.69, 95%CI 0.66-0.73, p 0.001).

WHAT IS NEW AND CONCLUSION

High-dose rifampicin was not a protective factor for 6-month mortality, despite increased plasma C_max and AUC_0-24h . However, the above conclusions are still required to be verified through more RCTs due to the limited quantity of included studies.

Management dilemmas in Nocardia brain infection

PURPOSE OF REVIEW

Brain nocardiosis is a rare but severe infection mostly occurring among immunocompromised patients. In this review, we present recent data on this infection and address some of the common clinical dilemmas encountered in patients with brain nocardiosis.

RECENT FINDINGS

Strategies used to approach a patient with suspected brain nocardiosis include the 'conservative strategy' (without early neurosurgery) and the 'neurosurgical strategy' (with early aspiration or excision of brain abscess[es]). The advantages and disadvantages of both strategies are summarised. Our opinion is that the use of the 'conservative strategy' should be limited to well-selected patients presenting with an easily accessible extra-neurological lesion(s) and have brain abscesses at low risk of treatment failure. In terms of antimicrobial therapy, we summarise the data supporting the use of a multidrug regimen in patients with brain nocardiosis.Last, we list possible reasons for treatment failure in patients with brain nocardiosis and suggest interventions to overcome them.

SUMMARY

Literature is scarce regarding brain nocardiosis, as a consequence of the rarity of this disease. A multidisciplinary and individualised management is required to optimise the outcome of patients with brain nocardiosis.

The neuroradiology of progressive multifocal leukoencephalopathy: a clinical trial perspective

Progressive multifocal leukoencephalopathy (PML) is an opportunistic infection of the central nervous system caused by the JC virus, which infects white and grey matter cells and leads to irreversible demyelination and neuroaxonal damage. Brain magnetic resonance imaging (MRI), in addition to the clinical presentation and demonstration of JC virus DNA either in the CSF or by histopathology, is an important tool in the detection of PML. In clinical practice, standard MRI pulse sequences are utilized for screening, diagnosis, and monitoring of PML, but validated imaging-based outcome measures for use in prospective, interventional clinical trials for PML have yet to be established. We review the existing literature regarding the use of MRI and positron emission tomography imaging in PML and discuss the implications of PML histopathology for neuroradiology. MRI not only demonstrates the localization and extent of PML lesions, but also mirrors the tissue destruction, ongoing viral spread, and resulting inflammation. Finally, we explore the potential for imaging measures to serve as an outcome in PML clinical trials and provide recommendations for current and future imaging outcome measure development in this area.

Human Immunodeficiency Viruses and its effect on the Pulmonary Vascular bed

December. 1^st 2021 is "World AIDS Day" reminding us that HIV infection is still widespread and that many of its long-term effects can be deadly. One of these complications is its effect on the pulmonary vascular beds, leading to an increase in the pulmonary pressure, causing the clinical manifestation of "pulmonary hypertension". Unfortunately, we are still far from fully understanding the prevalence, mechanics, and pathobiology of "HIV pulmonary hypertension", especially in Africa and other developing countries where HIV is still common. In addition, the impact of other factors like co-infection and illicit drugs can add and modify the effect on the pulmonary vascular bed, complicating the pathological and clinical effects of HIV. Thus, "World AIDS Day" can be an impetus to pursue further research in this area.

Differentiation of Acquired Immune Deficiency Syndrome Related Primary Central Nervous System Lymphoma from Cerebral toxoplasmosis with Use of Susceptibility-Weighted Imaging and Contrast Enhanced 3D-T1WI

BACKGROUND

We aimed to investigate whether susceptibility-weighted imaging (SWI) and contrast-enhanced 3D-T1WI can differentiate Acquired Immune Deficiency Syndrome-Related Primary Central Nervous System Lymphoma (AR-PCNSL) from cerebral toxoplasmosis.

METHODS

This was a prospective cohort study. 20 AIDS patients were divided into AR-PCNSL group (13 cases) and cerebral toxoplasmosis group (7 cases) based on pathology results. We analyzed the appearance of lesions on SWI and enhanced 3D T1WI and ROC curves in the diagnosis of AR-PCNSL and cerebral toxoplasmosis.

RESULTS

Cerebral toxoplasmosis was more likely to show annular enhancement (p = 0.002) and complete smooth ring enhancement (p = 0.002). It was also more likely to present a complete, smooth low signal intensity rim (LSIR) (p = 0.002) and an incomplete, smooth LSIR (p = 0.019) on SWI. AR-PCNSL was more likely to present an incomplete, irregular LSIR (p < 0.001) and irregular central low signal intensity (CLSI) (p<0.001) on SWI. The areas under the ROC curve of the SWI-ILSS grade and enhanced volume on 3D-T1WI were 0.872 and 0.862, respectively.

CONCLUSION

A higher SWI-ILSS grade and larger 3D-T1WI volume enhancement were diagnostic for AR-PCNSL. SWI and CE 3D-T1WI were useful in the differential diagnosis of AR-PCNSL and cerebral toxoplasmosis.

Contributions of the international plant science community to the fight against human infectious diseases - part 1: epidemic and pandemic diseases

Infectious diseases, also known as transmissible or communicable diseases, are caused by pathogens or parasites that spread in communities by direct contact with infected individuals or contaminated materials, through droplets and aerosols, or via vectors such as insects. Such diseases cause ˜17% of all human deaths and their management and control places an immense burden on healthcare systems worldwide. Traditional approaches for the prevention and control of infectious diseases include vaccination programmes, hygiene measures and drugs that suppress the pathogen, treat the disease symptoms or attenuate aggressive reactions of the host immune system. The provision of vaccines and biologic drugs such as antibodies is hampered by the high cost and limited scalability of traditional manufacturing platforms based on microbial and animal cells, particularly in developing countries where infectious diseases are prevalent and poorly controlled. Molecular farming, which uses plants for protein expression, is a promising strategy to address the drawbacks of current manufacturing platforms. In this review article, we consider the potential of molecular farming to address healthcare demands for the most prevalent and important epidemic and pandemic diseases, focussing on recent outbreaks of high-mortality coronavirus infections and diseases that disproportionately affect the developing world.

Prevalence of and Factors Associated with Reoccurrence of Opportunistic Infections Among Adult HIV/AIDS Patients Attending the ART Clinic at Public Health Facilities in Arba Minch Town, Southern Ethiopia

Background

Opportunistic infections (OIs) in human immunodeficiency virus (HIV)-positive individuals are infections that are more frequent or more severe than normal because of HIV-mediated immunosuppression. When these OIs occur in acquired immune deficiency syndrome (AIDS) patients in the form of relapse or reinfection, they are said to be a reoccurrence of OI. This study will try to identify gaps in addressing the burden in the study area.

Methods

This cross-sectional study was conducted among 450 HIV/AIDS patients with previous OIs attending a public health facility in Arba Minch Town, Southern Ethiopia. This study was conducted from 5 April 2020 to 20 April 2020. Computer-generated simple random sampling was used to select the study participants. Analysis was performed using SPSS version 25 statistical software. Bivariate and multivariable logistic regression was used to identify factors associated with the reoccurrence of OIs. A P value of ≤0.05 was used to determine significant association. The results were reported as numerical figures, tables, and diagrams, based on the type of data.

Results

The mean ± standard deviation age of the 450 study participants was 34.3±8.47 years. Eighty patients (17.8%) had chronic disease. In total, 119 HIV/AIDS patients (26.4%) were diagnosed with reoccurrence of OIs. Pulmonary tuberculosis was the major reoccurring OI. Age, rural residence, chronic disease, baseline anti-retroviral therapy (ART) adherence, current hemoglobin level, and current cell differentiation-4 (CD4) count were factors significantly associated with reoccurrence.

Conclusion

Although the magnitude of reoccurrence of OIs was lower than in previous studies, efforts have to be continued among stakeholders to tackle factors associated with the reoccurrence of OIs.

Accounting for misclassified and unknown cause of death data in vital registration systems for estimating trends in HIV mortality

INTRODUCTION

Misclassification of HIV deaths can substantially diminish the usefulness of cause of death data for decision-making. In this study, we describe the methods developed by the Global Burden of Disease Study to account for the misclassified cause of death data from vital registration systems for estimating HIV mortality in 132 countries and territories.

METHODS

The cause of death data were obtained from the World Health Organization Mortality Database and official country-specific mortality databases. We implemented two steps to adjust the raw cause of death data: (1) redistributing garbage codes to underlying causes of death, including HIV/AIDS by applying methods, such as analysis of multiple cause data and proportional redistribution, and (2) reassigning HIV deaths misclassified as other causes to HIV/AIDS by examining the age patterns of underlying causes in location and years with and without HIV epidemics.

RESULTS

In 132 countries, during the period from 1990 to 2018, 1,848,761 deaths were reported as caused by HIV/AIDS. After garbage code redistribution in these 132 countries, this number increased to 4,165,015 deaths. An additional 1,944,291 deaths were added through correction of HIV deaths misclassified as other causes in 44 countries. The proportion of HIV deaths derived from garbage code redistribution decreased over time, from 0.4 in 1990 to 0.1 in 2018. The proportion of deaths derived from HIV misclassification correction peaked at 0.4 in 2006 and declined afterwards to 0.08 in 2018. The greatest contributors to garbage code redistribution were "immunodeficiency antibody" (ICD 9: 279-279.1; ICD 10: D80-D80.9) and "immunodeficiency other" (ICD 9: 279, 279.5-279.9; ICD 10: D83-D84.9, D89, D89.8-D89.9), which together contributed 77% of all redistributed deaths at their peak in 1995. Respiratory tuberculosis (ICD 9: 010-012.9; ICD 10: A10-A14, A15-A16.9) contributed the greatest proportion of all HIV misclassified deaths (25-62% per year) over the most years.

CONCLUSIONS

Correcting for miscoding and misclassification of cause of death data can enhance the utility of the data for analyzing trends in HIV mortality and tracking progress toward the Sustainable Development Goal targets.

Encephalitis Due to Co-Infection with Cytomegalovirus and Herpes Simplex Virus Type 2 in a Patient with Acquired Immunodeficiency Syndrome

BACKGROUND Opportunistic infections are commonly seen in immunocompromised patients. Here, we present an interesting case of a patient with poorly controlled human immunodeficiency virus (HIV) infection who presented with multiple opportunistic infections. CASE REPORT A 44-year-old woman with medical history of HIV infection (CD4 <20 cells/µl, viral load 172 996 copies/ml), presented with symptoms of headache for 2 days and changes in mentation. She was recently treated for pulmonary mycobacterium avium complex infection. Her physical examination revealed normal breath sounds and her abdominal examination was unremarkable. She did not have any focal neurological deficits, nuchal rigidity, or papilledema on examination. Computed tomography (CT) head was negative for any acute lesions. She was empirically started on vancomycin and piperacillin-tazobactam. Due to persistent symptoms, a lumbar puncture was performed, which revealed elevated total proteins in CSF, and a viral polymerase chain reaction test was positive for herpes simplex virus type 2 (HSV-2) and cytomegalovirus (CMV). Magnetic resonance imaging of the brain showed mild enhancement of the ventricular lining. She was treated with acyclovir, which was later changed to ganciclovir, with resulting clinical improvement. The patient had clinical improvement and was discharged home. CONCLUSIONS Multiple opportunistic co-infections should be considered in patients with poorly controlled HIV infection.

Viral and Prion Infections Associated with Central Nervous System Syndromes in Brazil

Virus-induced infections of the central nervous system (CNS) are among the most serious problems in public health and can be associated with high rates of morbidity and mortality, mainly in low- and middle-income countries, where these manifestations have been neglected. Typically, herpes simplex virus 1 and 2, varicella-zoster, and enterovirus are responsible for a high number of cases in immunocompetent hosts, whereas other herpesviruses (for example, cytomegalovirus) are the most common in immunocompromised individuals. Arboviruses have also been associated with outbreaks with a high burden of neurological disorders, such as the Zika virus epidemic in Brazil. There is a current lack of understanding in Brazil about the most common viruses involved in CNS infections. In this review, we briefly summarize the most recent studies and findings associated with the CNS, in addition to epidemiological data that provide extensive information on the circulation and diversity of the most common neuro-invasive viruses in Brazil. We also highlight important aspects of the prion-associated diseases. This review provides readers with better knowledge of virus-associated CNS infections. A deeper understanding of these infections will support the improvement of the current surveillance strategies to allow the timely monitoring of the emergence/re-emergence of neurotropic viruses.