Seroprevalence Estimates of Latent and Acute Toxoplasma Infections in HIV+ People-Call for Action in Underprivileged Communities

In Silico-Based Investigation of the Immunogenicity and Biochemical Attributes of Toxoplasma gondii Apical Membrane Antigen 1 (TgAMA1)

Background: Apical membrane antigen 1 (AMA1) is a highly conserved microneme protein in apicomplexan parasites. In this study, immunoinformatics tools and in silico protein structure prediction were used to characterize the structure, physicochemical properties, posttranslational modification sites, immunogenic epitopes, allergenicity, and immune simulation of the Toxoplasma gondii AMA1 (TgAMA1) protein. Methods: A comprehensive analysis was performed using multiple bioinformatics web servers to analyze the antigenicity, physicochemical features, secondary and tertiary structures, B and T cell epitopes, and in silico immune simulation of TgAMA1. Results: The analysis revealed that the AMA1 protein consists of 569 amino acid residues and has a molecular weight of approximately 63 kDa. The grand average of hydropathicity (GRAVY) was -0.531 and the aliphatic index was calculated as 64.62. Based on the GOR IV server, TgAMA1 contained 20.21% alpha helices, 58.52% random coils, and 21.27% extended strands. The Ramachandran plot of the refined model revealed that over 97% of the residues were located in the favored region. The AMA1 protein was highly immunogenic and nonallergenic in nature. In silico immune simulation using the C-ImmSim server suggested that three doses of TgAMA1 would elicit potent humoral and cell-mediated immune responses. Conclusion: These findings provide valuable insights for further in vitro and in vivo investigations of TgAMA1's potential as a vaccine candidate against toxoplasmosis.

Motility-dependent processes in Toxoplasma gondii tachyzoites and bradyzoites: same same but different

During infection, Toxoplasma gondii tachyzoites must be able to move in order to migrate through tissues, cross biological barriers, and penetrate into and egress from cells they infect. Bradyzoite-stage parasites, which establish infection in naïve hosts, also require motility to escape from cysts after they are ingested and to subsequently migrate to the gut wall, where they either invade cells of the intestinal epithelium or squeeze between these cells to infect the underlying tissue. Little is known about the motility of bradyzoites, which we analyze in detail here and compare to the well-characterized motility and motility-dependent processes of tachyzoites. Unexpectedly, bradyzoites were found to be as motile as tachyzoites in a three-dimensional model extracellular matrix, and they showed increased invasion into and transmigration across monolayers of certain cell types, consistent with their need to establish infection in the gut. The motility of the two stages was inhibited to the same extent by cytochalasin D and KNX-002, compounds known to target the parasite's actomyosin-based motor. Other compounds that impact tachyzoite motility (tachyplegin and enhancer 5) have a reduced effect on bradyzoites. Furthermore, rapid bradyzoite egress from infected cells is not triggered by treatment with calcium ionophores, as it is with tachyzoites. The similarities and differences between these two life cycle stages highlight the need to characterize both tachyzoites and bradyzoites for a more complete understanding of the role of motility in the parasite life cycle and the effect that motility-targeting therapeutics will have on disease establishment and progression.

IMPORTANCE

Toxoplasma gondii is a parasite that chronically infects around one-third of the world's population. Toxoplasma uses motility for multiple purposes during infection, including extracellular migration, invasion into host cells, and host cell egress. These motility-dependent processes have been extensively studied in the life cycle stage responsible for acute infection, the tachyzoite. In contrast, motility and motility-dependent processes are poorly understood in bradyzoite-stage parasites, which are responsible for both establishing infection after consumption of infected meat and initiating potentially life-threatening reactivated infections in the brains of immunocompromised individuals. We show here that the motility and motility-dependent processes of bradyzoites are similar in many respects to those of tachyzoites but markedly different in others. The results of this study highlight the need to consider both life cycle stages in attempts to develop drugs targeting parasite motility and the signaling processes that regulate motility-dependent processes during infection by these important human pathogens.

In Silico Analysis and Characterization of the Immunogenicity of Toxoplasma gondii Rhoptry Protein 18

Rhoptry protein 18 (ROP18) is a key virulence factor secreted into host cells during the invasion of Toxoplasma gondii (T. gondii) and plays an important role in the pathogenesis of infection. Due to its potential as a vaccine candidate, this study aimed to characterize several properties of the T. gondii ROP18 (TgROP18) protein to support its inclusion in vaccine formulations. Using a range of bioinformatics tools, we investigated its T-cell and B-cell epitopes, physicochemical properties, subcellular localization, transmembrane domains, and tertiary and secondary structures. Our analysis revealed 48 post-translational modification sites in TgROP18. The secondary structure was composed of 4.87% beta-turns, 38.45% random coils, 42.42% alpha helices, and 14.26% extended strands. Several potential T- and B-cell epitopes were identified on ROP18. The Ramachandran plot of both crude and refined models showed that 85.8% and 95.3% of the amino acid residues, respectively, fell within favored regions, indicating energetically stable conformations. Allergenicity and antigenicity assessments indicated that TgROP18 is a nonallergenic, immunogenic protein. Predictions using the C-ImmSim server suggest that TgROP18 can stimulate humoral and cell-mediated immune responses, based on antibody titers and cytokine profiles following antigen administration. These findings provide baseline data for future investigations focused on the potential of TgROP18 in developing therapeutic strategies against toxoplasmosis.

Serological Profile of Anti-Toxoplasma gondii Antibodies in Liver Transplant Recipients

Toxoplasma gondii (T. gondii), a globally distributed obligatory intracellular opportunistic parasite that has infected one third of the world population, has different transmission routes including via organ transplantation. The liver has emerged as a frequent transplanted organ in which the transmission of T. gondii can occur between seropositive donors and seronegative recipients. Allied with immunosuppressive therapy, the presence of latent infection in recipients elevates the risk of severe toxoplasmosis. The goal of this study was to evaluate the demographic, clinical, epidemiological, and anti-T. gondii antibody profiles in liver transplant recipients. All demographic, clinical, epidemiological, and serological data were obtained from the electronic medical records of liver transplant recipients from the Liver Transplantation Service of the Hospital de Base in São José do Rio Preto, Brazil, from 2008 to 2018. Data from 48 eligible recipients (females: n = 17; males: n = 31) were evaluated. The recipients were grouped according to their T. gondii serological profiles (G1: IgM-/IgG-; G2: IgM-/IgG+; G3: IgM+/IgG+; G4: IgM+/IgG-). The overall mean age was 55.3 (±15.3) years; the age difference between women (42.7 ± 17 years) and men (62.2 ± 10.9 years) was statistically significant (p-value > 0.0001). The percentages of the serological profiles were 20 (n = 41.7%), 26 (n = 54.1%), and 2 (n = 4.2%) for G1, G2, and G3, respectively. No recipient had a serological profile for G4. Hepatosplenomegaly (47.9%), fever (35.4%), encephalopathy (20.8%), and headache (16.7%) were commonly observed symptoms. No statistically significant differences were observed between the serological group and clinical data (p-value = 0.953). The percentages of coinfection by T. gondii with hepatitis A, B, and C were 47.9%, 20.8%, and 12.5%, respectively. About 41.7% of the recipients later died. The data demonstrate that infection by T. gondii is common in liver transplant recipients, and it is not associated with the analyzed demographic, clinical, and epidemiological data.

Motility-dependent processes in Toxoplasma gondii tachyzoites and bradyzoites: same same but different

The tachyzoite stage of the apicomplexan parasite Toxoplasma gondii utilizes motility for multiple purposes during its lytic cycle, including host cell invasion, egress from infected cells, and migration to new uninfected host cells to repeat the process. Bradyzoite stage parasites, which establish a new infection in a naïve host, must also use motility to escape from the cysts that are ingested by the new host and then migrate to the gut wall, where they either invade cells of the intestinal epithelium or squeeze between these cells to infect the underlying connective tissue. We know very little about the motility of bradyzoites, which we analyze in detail here and compare to the well-characterized motility and motility-dependent processes of tachyzoites. Unexpectedly, bradyzoites were found to be as motile as tachyzoites in a 3D model extracellular matrix, and they showed increased invasion into and transmigration across certain cell types, consistent with their need to establish the infection in the gut. The motility of the two stages was inhibited to the same extent by cytochalasin D and KNX-002, compounds known to target the parasite's actomyosin-based motor. In contrast, other compounds that impact tachyzoite motility (tachyplegin and enhancer 5) have less of an effect on bradyzoites, and rapid bradyzoite egress from infected cells is not triggered by treatment with calcium ionophores, as it is with tachyzoites. The similarities and differences between these two life cycle stages highlight the need to characterize both tachyzoites and bradyzoites for a more complete understanding of the role of motility in the parasite life cycle and the effect that potential therapeutics targeting parasite motility will have on disease establishment and progression.

New advances in immune mechanism and treatment during ocular toxoplasmosis

Ocular toxoplasmosis (OT) is an intraocular infection caused by the parasite Toxoplasma gondii. OT is manifested as retinal choroiditis and is the most common infectious cause of posterior uveitis. Invasion of the retina by T. gondii leads to disruption of the blood-ocular barrier and promotes the migration of immune cells to the ocular tissues. Cytokines such as IFN-γ and IL-1β are effective for controlling parasite growth, but excessive inflammatory responses can cause damage to the host. In this review, we will discuss in detail the latest advances in the immunopathology and treatment of OT.

Ongoing Healthcare Disparities in neuroHIV: Addressing Gaps in the Care Continuum

PURPOSE OF REVIEW

We aim to review the neurological complications of HIV and the social, cultural, and economic inequalities that contribute to disparities in neuroHIV care.

RECENT FINDINGS

Disparities in diagnostics and care of patients with neurological infections and non-infectious conditions associated with HIV in both high-income and low-to-middle-income countries (LMIC) are common. The COVID-19 pandemic has exacerbated these disparities. Factors, such as HIV-related stigma, may deter people from accessing HIV treatment. First-line recommended treatments for neurological infections are not available in many LMICs, leading to inadequate treatment and exposure to agents with more harmful side effect profiles. Access-related factors, such as lack of transportation, lack of health insurance, and inadequate telehealth access, may increase the risk of HIV-related neurological complications. Further research is needed to increase awareness of neurological complications among providers and PWH, and regional guidelines should be considered to better address these complications.

A Case-Control Seroprevalence Survey of Toxoplasmosis in Hemodialysis Patients and Healthy Subjects in Kazeroon and Jahrom Districts in Fars Province, Southern Iran

Opportunistic parasites such as Toxoplasma gondii (T. gondii) are capable of causing neurological and ocular manifestations in patients undergoing hemodialysis. By designing a matched case-control study, we conducted a seromolecular survey of T. gondii in hemodialysis patients compared to a healthy group from Jahrom and Kazeroon cities in Fars Province, Iran. For this purpose, 75 hemodialysis patients from Kazeroon city, 75 hemodialysis patients from Jahrom city, and 75 healthy individuals were recruited for the study. The serum levels of specific immunoglobulins (IgG/IgM) in the case and control groups were evaluated using the enzyme-linked immunosorbent assay (ELISA) method. Also, buffy coat samples were used to extract genomic DNA. Then, Polymerase Chain Reaction (PCR) was accomplished using the RE and GRA6 genes of T. gondii. A standard questionnaire containing demographic factors was administered. Although the seroprevalence of the anti-T. gondii IgG antibody in hemodialysis patients from Kazeroon (18.66% (14/75)) and Jahrom (25.33% (19/75)) was higher than that in the control group (13.33% (10/75)), no statistically significant difference was observed between the case and control groups (P value = 0.373 from Kazeroon and P value = 0.354 from Jahrom). Among the studied variables, only residence (urban) was significantly associated with the anti-T. gondii IgG antibody in the case group from Kazeroon. Also, no IgM antibody titers and DNA of T. gondii were detected in the case and control groups from both cities. Although high seroprevalence of anti-T. gondii IgG antibody was seen in hemodialysis patients, further epidemiological studies with larger samples need to be done in Jahrom and Kazeroon cities and in other parts of Iran. It is also necessary for health officials to establish programs for the prevention and control of T. gondii infection in hemodialysis patients.

Health inequalities in infectious diseases: a systematic overview of reviews

OBJECTIVES

The aim of this systematic overview of reviews was to synthesise available evidence on inequalities in infectious disease based on three dimensions of inequalities; inclusion health groups, protected characteristics and socioeconomic inequalities.

METHODS

We searched MEDLINE, Embase, Web of Science and OpenGrey databases in November 2021. We included reviews published from the year 2000 which examined inequalities in the incidence, prevalence or consequences of infectious diseases based on the dimensions of interest. Our search focused on tuberculosis, HIV, sexually transmitted infections, hepatitis C, vaccination and antimicrobial resistance. However, we also included eligible reviews of any other infectious diseases. We appraised the quality of reviews using the Assessment of Multiple Systematic Reviews V.2 (AMSTAR2) checklist. We conducted a narrative data synthesis.

RESULTS

We included 108 reviews in our synthesis covering all the dimensions of inequalities for most of the infectious disease topics of interest, however the quality and volume of review evidence and consistency of their findings varied. The existing literature reviews provide strong evidence that people in inclusion health groups and lower socioeconomic status are consistently at higher risk of infectious diseases, antimicrobial resistance and incomplete/delayed vaccination. In the protected characteristics dimension, ethnicity, and sexual orientation are important factors contributing to inequalities across the various infectious disease topics included in this overview of reviews.

CONCLUSION

We identified many reviews that provide evidence of various types of health inequalities in different infectious diseases, vaccination, and antimicrobial resistance. We also highlight areas where reviews may be lacking. The commonalities in the associations and their directions suggest it might be worth targeting interventions for some high risk-groups that may have benefits across multiple infectious disease outcomes rather than operating purely in infectious disease siloes.

Toxoplasma gondii, HBV, and HCV co-infection and their correlation with CD4 cells among Iranian HIV-positive patients

INTRODUCTION

Human immunodeficiency virus (HIV/AIDS) infected patients have a higher risk of opportunistic infections (OIs) depending on their immunological status, especially CD4 + cell count. Toxoplasma gondii, hepatitis C virus (HCV), and hepatitis B virus (HBV) are important OIs among Human Immunodeficiency Virus (HIV)/Acquired Immune Deficiency Syndrome (AIDS) patients. However, little is known about co-infection of these pathogens among HIV-infected individuals and their correlation with the patient's CD4 + cell count. Hence, this study aimed to investigate the serological and molecular status of T. gondii infection among HIV-infected individuals who had co-infection with HBV and HCV infections.

METHODS

A total of 100 HIV/AIDS patients in two cities in the southwest of Iran was tested for T. gondii Immunoglobulin G (IgG) and Immunoglobulin M (IgM) antibodies as well as DNA detection by polymerase chain reaction (PCR) targeting the RE gene. HBV and HCV were detected by hepatitis B surface antigen (HBsAg) test, hepatitis C antibody (HCV Ab) test, and Real-Time PCR. The number of CD4 + cell counts was determined by Flow cytometry.

RESULTS

Anti-T. gondii IgG was positive in 22% of the patients, but anti-T. gondii IgM and PCR were negative in all samples. HBV and HCV were positive in 8% and 33% of the patients, respectively. Co-infections were as followed: HIV + HCV (16%), HIV + HCV + T. gondii (11%), HIV + T. gondii (5%), HIV + HBV (1%), HIV + HBV + T. gondii (1%), HIV + HBV + HCV (1%), and HIV + HBV + HCV + T. gondii (5%). A significant decline in CD4 + cell counts was found in such co-infection groups (HIV + T. gondii, HIV + HCV + T. gondii, and HIV + HBV + HCV + T. gondii) compared with the HIV mono-infection group.

CONCLUSIONS

Our study showed that co-infections of T. gondii, HCV, and HBV were common among HIV-infected patients and co-infections had a negative correlation with CD4 + cell counts of the patients.

Primary Toxoplasma gondii infection-associated with hemophagocytic syndrome in a man with HIV infection: a case report

Background

Reactivation of latent Toxoplasma gondii (T. gondii) infection is more common than primary infection in patients with human immunodeficiency virus (HIV). We report a rare case of primary T. gondii infection-associated hemophagocytic syndrome (HPS).

Case presentation

A man with HIV infection presented with fever, dyspnea and pancytopenia. He was diagnosed with primary T. gondii infection by the seroconversion from single-positive IgM antibody to double-positive IgM and IgG antibody. Metagenomic next-generation sequencing (mNGS) of a plasma sample yielded high reads of T. gondii DNA. He responded well to combined anti-Toxoplasma medicines and glucocorticoid treatment.

Conclusions

In patients with HPS and positive T. gondii IgM antibody, mNGS analysis of a peripheral blood sample is helpful in diagnosing disseminated T. gondii infection. The dynamic changes by serological detection for IgM and IgG of T. gondii further supported the inference that the patient has experienced a primary T. gondii infection.

Parasitic and Vector-Borne Infections in HIV-Positive Patients in Slovakia-Evidence of an Unexpectedly High Occurrence of Anaplasma phagocytophilum

In HIV (human immunodeficiency virus) infected people, the immunodeficiency caused by a reduced level of CD4 (cluster of differentiation 4) T-lymphocytes increases the risk of infectious diseases. Additionally, in individuals with immunologically compromising conditions, tick-borne or some parasitic pathogens may cause chronic, debilitating opportunistic infections and even death. The study aimed at determining the IgG seropositivity of HIV-infected patients to Toxoplasma gondii, Toxocara spp., Echinococcus multilocularis, and E. granulosus s.l. and performing the molecular identification of T. gondii and some tick-borne pathogens, namely, Borrelia spp., Babesia spp., Anaplasma phagocytophilum, Rickettsia spp., and Bartonella spp. Out of 89 HIV-positive patients, specific IgG antibodies to T. gondii were detected in 17 (19.1%) and to Borrelia spp. in 12 (13.5%) individuals. Seropositivity to Toxocara spp., E. multilocularis, and E. granulosus s.l. was not recorded. Molecular approaches showed positivity to T. gondii in two (2.2%) patients, and 11 (12.4%) individuals had positive PCR signal for the msp2 gene of A. phagocytophilum. Relatively high prevalence of A. phagocytophilum in HIV-positive patients suggests that these people are more susceptible to some vector-borne pathogens. The presence of opportunistic infections may pose a health risk for patients with weakened immune systems, and should not be neglected during the regular monitoring of the patient’s health status.

Is Toxoplasma gondii Infection Associated with Sexual Promiscuity? A Cross-Sectional Study

We determined the association between T. gondii seropositivity and a history of sexual promiscuity. The study included 3933 people (mean age: 41.81 ± 14.31 years) who attended public health facilities. Face-to-face interviews were used to collect data. Enzyme immunoassays were used to determine anti-T. gondii IgG and IgM antibodies. Anti-T. gondii IgG antibodies were found in 57 (18.1%) of 315 individuals with sexual promiscuity and in 374 (10.3%) of 3618 individuals without this practice (OR: 1.91; 95% CI: 1.41–2.60; p < 0.0001). High (>150 IU/mL) levels of anti-T. gondii IgG antibodies were found in 29 (9.2%) of the 315 participants with sexual promiscuity and in 167 (4.6%) of the 3618 participants without this history (OR: 2.09; 95% CI: 1.38–3.16; p = 0.0003). The association of sexual promiscuity with T. gondii seropositivity and serointensity was observed in men but not in women. Sexual promiscuity was associated with T. gondii seropositivity in all age groups studied (≤30 years, 31–50 years, and >50 years) and with T. gondii serointensity in two age groups (≤30 years, and >50 years). No difference in the frequencies of anti-T. gondii IgM antibodies among the groups was found. Our findings indicate that T. gondii seropositivity and serointensity are associated with sexual promiscuity.