A conserved motif in the immune-subdominant RAP-1 related antigen of Babesia bovis contains a B-cell epitope recognized by antibodies from protected cattle.

Introduction: Babesia bovis, a tick-borne apicomplexan parasite causing bovine babesiosis, remains a significant threat worldwide, and improved and practical vaccines are needed. Previous studies defined the members of the rhoptry associated protein-1 (RAP-1), and the neutralization-sensitive rhoptry associated protein-1 related antigen (RRA) superfamily in B. bovis, as strong candidates for the development of subunit vaccines. Both RAP-1 and RRA share conservation of a group of 4 cysteines and amino acids motifs at the amino terminal end (NT) of these proteins. Methods and results: Sequence comparisons among the RRA sequences of several B. bovis strains and other Babesia spp parasites indicate a high level of conservation of a 15-amino acid (15-mer) motif located at the NT of the protein. BlastP searches indicate that the 15-mer motif is also present in adenylate cyclase, dynein, and other ATP binding proteins. AlphaFold2 structure predictions suggest partial exposure of the 15-mer on the surface of RRA of three distinct Babesia species. Antibodies in protected cattle recognize a synthetic peptide representing the 15-mer motif sequence in iELISA, and rabbit antibodies against the 15-mer react with the surface of free merozoites in immunofluorescence. Discussion and conclusion: The presence of the 15-mer-like regions in dynein and ATP-binding proteins provides a rationale for investigating possible functional roles for RRA. The demonstrated presence of a surface exposed B-cell epitope in the 15-mer motif of the B. bovis RRA, which is recognized by sera from protected bovines, supports its inclusion in future subunit epitope-based vaccines against B. bovis.

A combination of GRA3, GRA6 and GRA7 peptides offer a useful tool for serotyping type II and III Toxoplasma gondii infections in sheep and pigs.

The clinical consequences of toxoplasmosis are greatly dependent on the Toxoplasma gondii strain causing the infection. To better understand its epidemiology and design appropriate control strategies, it is important to determine the strain present in infected animals. Serotyping methods are based on the detection of antibodies that react against segments of antigenic proteins presenting strain-specific polymorphic variations, offering a cost-effective, sensitive, and non-invasive alternative to genotyping techniques. Herein, we evaluated the applicability of a panel of peptides previously characterized in mice and humans to serotype sheep and pigs. To this end, we used 51 serum samples from experimentally infected ewes (32 type II and 19 type III), 20 sheep samples from naturally infected sheep where the causative strain was genotyped (18 type II and 2 type III), and 40 serum samples from experimentally infected pigs (22 type II and 18 type III). Our ELISA test results showed that a combination of GRA peptide homologous pairs can discriminate infections caused by type II and III strains of T. gondii in sheep and pigs. Namely, the GRA3-I/III-43 vs. GRA3-II-43, GRA6-I/III-213 vs. GRA6-II-214 and GRA6-III-44 vs. GRA6-II-44 ratios showed a statistically significant predominance of the respective strain-type peptide in sheep, while in pigs, in addition to these three peptide pairs, GRA7-II-224 vs. GRA7-III-224 also showed promising results. Notably, the GRA6-44 pair, which was previously deemed inefficient in mice and humans, showed a high prediction capacity, especially in sheep. By contrast, GRA5-38 peptides failed to correctly predict the strain type in most sheep and pig samples, underpinning the notion that individual standardization is needed for each animal species. Finally, we recommend analyzing for each animal at least 2 samples taken at different time points to confirm the obtained results.

Immunotherapy Combining Mimotopes Selected by Phage Display Plus Amphotericin B Is Effective for Treatment Against Visceral Leishmaniasis.

The treatment for visceral leishmaniasis (VL) causes toxicity in patients, entails high cost and/or leads to the emergence of resistant strains. No human vaccine exists, and diagnosis presents problems related to the sensitivity or specificity of the tests. Here, we tested two phage clones, B1 and D11, which were shown to be protective against Leishmania infantum infection in a murine model as immunotherapeutics to treat mice infected with this parasite species. The phages were used alone or with amphotericin B (AmpB), while other mice received saline, AmpB, a wild-type phage (WTP) or WTP/AmpB. Results showed that the B1/AmpB and D11/AmpB combinations induced polarised Th1-type cellular and humoral responses, which were primed by high levels of parasite-specific IFN-γ, IL-12, TNF-α, nitrite and IgG2a antibodies, which reflected in significant reductions in the parasite load in distinct organs of the animals when analyses were performed 1 and 30 days after the treatments. Reduced organic toxicity was also found in these animals, as compared with the controls. In conclusion, preliminary data suggest the potential of the B1/AmpB and D11/AmpB combinations as immunotherapeutics against L. infantum infection.

Efficient transplacental transfer of SARS-CoV-2 antibodies between naturally exposed mothers and infants in Accra, Ghana.

We aimed to determine SARS-CoV-2 antibody seropositivity among pregnant women and the transplacental transfer efficiency of SARS-CoV-2-specific antibodies relative to malaria antibodies among SARS-CoV-2 seropositive mother-cord pairs. This cross-sectional study was conducted in Accra, Ghana, from March to May 2022. Antigen- specific IgG antibodies against SARS-CoV-2 (nucleoprotein and spike-receptor binding domain) and malarial antigens (circumsporozoite protein and merozoite surface protein 3) in maternal and cord plasma were measured by ELISA. Plasma from both vaccinated and unvaccinated pregnant women were tested for neutralizing antibodies using commercial kit. Of the unvaccinated pregnant women tested, 58.12% at antenatal clinics and 55.56% at the delivery wards were seropositive for both SARS-CoV-2 nucleoprotein and RBD antibodies. Anti-SARS-CoV-2 antibodies in cord samples correlated with maternal antibody levels (N antigen rs = 0.7155, p < 0.001; RBD rs = 0.8693, p < 0.001). Transplacental transfer of SARS-CoV-2 nucleoprotein antibodies was comparable to circumsporozoite protein antibodies (p = 0.9999) but both were higher than transfer rates of merozoite surface protein 3 antibodies (p < 0.001). SARS-CoV-2 IgG seropositivity among pregnant women in Accra is high with a boost of SARS-CoV-2 RBD-specific IgG in vaccinated women. Transplacental transfer of anti-SARS-CoV-2 and malarial antibodies was efficient, supporting vaccination of mothers as a strategy to protect infants against SARS-CoV-2.

Seroprevalence and risk factors of Toxoplasma gondii in goats (Capra hircus) in the state of Espírito Santo, Southeast Brazil.

Toxoplasma gondii is described as a potential cause of abortion in goats and as a threat to public health. To estimate the prevalence of goats infected by T. gondii, in different cities in the Espírito Santo State, and to identify possible risk factors for infection a serological study was conducted. A total of 146 goat serum samples from the cities of Cariacica, Serra and Vila Velha were analyzed. The presence of IgG Class Immunoglobulins was serologically evaluated by Immunofluorescence antibody test (IFAT) and by Enzyme-linked Immunosorbent Assay (ELISA). The seroprevalence of anti-T. gondii was 46.6% (68/146) in both techniques and the same samples got the same results in both techniques. Among the analyzed sera, 70.6% (48/68) exhibited high-avidity IgG antibodies, and 29.4% (20/68) exhibited low-avidity IgG antibodies, suggesting that the infection was chronic in the infected animals. Female sex, age group over two years old, water from the public supply system, storage of food and supplies in an open and unprotected place, and the presence of a domestic cat on the property were identified as risk factors for T. gondii infection in goats. The state of Espirito Santo has a high frequency of infected goats, and this is the first research on caprine toxoplasmosis seroepidemiology in that region.

IgG and IgM responses to the Plasmodium falciparum asexual stage antigens reflect respectively protection against malaria during pregnancy and infanthood.

BACKGROUND: Plasmodium falciparum malaria is a public health issue mostly seen in tropical countries. Until now, there is no effective malaria vaccine against antigens specific to the blood-stage of P. falciparum infection. Because the pathogenesis of malarial disease results from blood-stage infection, it is essential to identify the most promising blood-stage vaccine candidate antigens under natural exposure to malaria infection. METHODS: A cohort of 400 pregnant women and their infants was implemented in South Benin. An active and passive protocol of malaria surveillance was established during pregnancy and infancy to precisely ascertain malaria infections during the follow-up. Twenty-eight antibody (Ab) responses specific to seven malaria candidate vaccine antigens were repeatedly quantified during pregnancy (3 time points) and infancy (6 time points) in order to study the Ab kinetics and their protective role. Abs were quantified by ELISA and logistic, linear and cox-proportional hazard model were performed to analyse the associations between Ab responses and protection against malaria in mothers and infants, taking into account socio-economic factors and for infants an environmental risk of exposure. RESULTS: The levels of IgM against MSP1, MSP2 and MSP3 showed an early protective response against the onset of symptomatic malaria infections starting from the 18th month of life, whereas no association was found for IgG responses during infancy. In women, some IgG responses tend to be associated with a protection against malaria risk along pregnancy and at delivery, among them IgG3 against GLURP-R0 and IgG2 against MSP1. CONCLUSION: The main finding suggests that IgM should be considered in vaccine designs during infanthood. Investigation of the functional role played by IgM in malaria protection needs further attention.

An investigation into Toxoplasma gondii at the human-livestock-wildlife interface, South Africa.

Interface areas shared by humans, domestic and wild animals may serve as high transmission contexts for Toxoplasma gondii. However, knowledge about the epidemiology of T. gondii in such areas is currently limited. The present study assessed the seroprevalence of T. gondii in different hosts from Mpumalanga, South Africa. Furthermore, we investigated the local knowledge and related practices about T. gondii by conducting a questionnaire study in the community. Blood samples were obtained and analysed for T. gondii antibodies using a commercial multispecies latex agglutination kit. The seroprevalence detected in humans (n = 160; patients showing signs of acute febrile illness), cats (n = 9), chickens (n = 336) and goats (n = 358) was 8.8%, 0.0%, 4.2% and 11.2%, respectively. Seroprevalence in impalas (n = 97), kudus (n = 55), wild dogs (n = 54), wildebeests (n = 43), warthogs (n = 97) and zebras (n = 68) was calculated at 5.2%, 7.3%, 100.0%, 20.9%, 13.4% and 9.1%, respectively. The questionnaire revealed that 63.0% of household owners were subsistence farmers, and 35.9% were pet owners. A high level of female participation was found (75.3%) when compared to male participation (24.7%). The results show a low circulation of T. gondii in the domestic cycle and suggest the presence of possible bridges between the wildlife cycle and the surrounding domestic cycle.Contribution: The study contributes to identifying transmission patterns and risk factors of T. gondii within human and animal populations. This topic fits within the scope of the journal presenting original research in veterinary science, with the focus on wild and domestic populations on the African continent on a topic of universal importance.

Geoepidemiology, seroprevalence and factors associated with Toxoplasma gondii infection in domicilied cats from Paraíba (Brazil).

Toxoplasma gondii is a parasite responsible for toxoplasmosis, an emerging and often neglected zoonosis in South America, particularly Brazil. Felines, the only definitive hosts, excrete oocysts in their feces, potentially infecting all homeotherms. Domestic cats are primarily responsible for contaminating human environments with these oocysts. Monitoring their populations is therefore essential to ensure proper toxoplasmosis prophylaxis. The aim of this study was to estimate the prevalence of T. gondii and exposure factors in a population of owner cats in the city of João Pessoa, Paraíba, Brazil. A total of 267 blood samples were collected from domestic cats aged between 1 and 15 years and tested with an immunofluorescence antibody test. The seroprevalence of antibodies against T. gondii was only 17.22% (46/267 individuals). This result therefore suggests a low contribution of domestic cats to T. gondii contamination of the urban environment. The cats' age and living environment were identified as risk factors for cat exposure to T. gondii.

Title: Géoépidémiologie, séroprévalence et facteurs associés à l'infection à Toxoplasma gondii chez les chats domiciliés à Paraíba (Brésil). Abstract: Toxoplasma gondii est le parasite responsable de la toxoplasmose, une zoonose émergente et souvent négligée en Amérique du Sud, notamment au Brésil. Les félins, seuls hôtes définitifs, excrètent des oocystes dans leurs selles, infectant potentiellement tous les homéothermes. Les chats domestiques sont les premiers responsables de la contamination des environnements humains avec ces oocystes. La surveillance de leurs populations est donc essentielle pour garantir une prophylaxie adéquate contre la toxoplasmose. Le but de cette étude était d'estimer la prévalence de T. gondii et les facteurs d'exposition dans une population de chats domestiques de la ville de João Pessoa, Paraíba, Brésil. Au total, 267 échantillons de sang ont été prélevés sur des chats domestiques âgés de 1 à 15 ans et testés avec un test d'immunofluorescence des anticorps. La séroprévalence des anticorps contre T. gondii n'était que de 17,22 % (46/267 individus). Ce résultat suggère donc une faible contribution des chats domestiques à la contamination du milieu urbain par T. gondii. L'âge et le milieu de vie des chats ont été identifiés comme facteurs de risque d'exposition du chat à T. gondii.

A two-dose viral-vectored Plasmodium vivax multistage vaccine confers durable protection and transmission-blockade in a pre-clinical study.

Among Plasmodium spp. responsible for human malaria, Plasmodium vivax ranks as the second most prevalent and has the widest geographical range; however, vaccine development has lagged behind that of Plasmodium falciparum, the deadliest Plasmodium species. Recently, we developed a multistage vaccine for P. falciparum based on a heterologous prime-boost immunization regimen utilizing the attenuated vaccinia virus strain LC16m8Δ (m8Δ)-prime and adeno-associated virus type 1 (AAV1)-boost, and demonstrated 100% protection and more than 95% transmission-blocking (TB) activity in the mouse model. In this study, we report the feasibility and versatility of this vaccine platform as a P. vivax multistage vaccine, which can provide 100% sterile protection against sporozoite challenge and >95% TB efficacy in the mouse model. Our vaccine comprises m8Δ and AAV1 viral vectors, both harboring the gene encoding two P. vivax circumsporozoite (PvCSP) protein alleles (VK210; PvCSP-Sal and VK247; -PNG) and P25 (Pvs25) expressed as a Pvs25-PvCSP fusion protein. For protective efficacy, the heterologous m8Δ-prime/AAV1-boost immunization regimen showed 100% (short-term; Day 28) and 60% (long-term; Day 242) protection against PvCSP VK210 transgenic Plasmodium berghei sporozoites. For TB efficacy, mouse sera immunized with the vaccine formulation showed >75% TB activity and >95% transmission reduction activity by a direct membrane feeding assay using P. vivax isolates in blood from an infected patient from the Brazilian Amazon region. These findings provide proof-of-concept that the m8Δ/AAV1 vaccine platform is sufficiently versatile for P. vivax vaccine development. Future studies are needed to evaluate the safety, immunogenicity, vaccine efficacy, and synergistic effects on protection and transmission blockade in a non-human primate model for Phase I trials.

Impact of latent toxoplasmosis on pneumonic and non-pneumonic COVID-19 patients with estimation of relevant oxidative stress biomarkers.

Susceptibility to COVID-19, the most devastating global pandemic, appears to vary widely across different population groups. Exposure to toxoplasmosis has been proposed as a theory to explain the diversity of these populations. The aim of the present study was to investigate the possible association between latent toxoplasmosis and COVID-19 and its probable correlation with markers of oxidative stress, C-reactive protein (CRP) and ferritin. In a case-control study, blood samples were collected from 91 confirmed (48 non-pneumonic; NP, and 43 pneumonic; P) COVID-19 patients and 45 healthy controls. All participants were tested for IgG anti-Toxoplasma gondii antibodies and oxidative stress markers (nitric oxide [NO], superoxide dismutase [SOD] and reduced glutathione [GSH]), and CRP and serum ferritin levels were determined. In COVID-19 patients, IgG anti-T. gondii antibodies were found in 54% compared to 7% in the control group, with the difference being statistically significant (P ˂ 0.001). However, no significant correlation was found between the severity of COVID-19 and latent T. gondii infection. Latent toxoplasmosis had a strong influence on the risk of COVID-19. NO and SOD levels were significantly increased in COVID-19 patients, while GSH levels decreased significantly in them compared to control subjects (P ˂ 0.001 for both values). CRP and ferritin levels were also significantly elevated in P COVID-19 patients infected with toxoplasmosis. This is the first study to look at the importance of oxidative stress indicators in co-infection between COVID-19 and T. gondii. The high prevalence of latent toxoplasmosis in COVID-19 suggests that T. gondii infection can be considered a strong indicator of the high risk of COVID-19.

Seromolecular study on the prevalence and risk factors of Toxoplasma gondii infection in pregnant women referred to a gynecology hospital in Urmia, northwest part of Iran in 2022.

Toxoplasmosis is a frequent infection among the human population. The infection can cause devastating complications for the fetus during pregnancy. The present study aimed to determine the serological and molecular prevalence of the infection and molecular characterization of Toxoplasma gondii isolates among pregnant women referred to Kowsar Hospital, Urmia, Iran. In a cross-sectional study, 340 blood samples were collected from pregnant women referred to Kowsar Hospital, Urmia, Iran from May to July 2022. Anti-T. gondii IgG and IgM seropositivity were determined by enzyme-linked immunosorbent assay. PCR was carried out by targeting the GRA6 gene of the parasite on all patients' buffy coats. Anti-T. gondii IgG and IgM antibodies were positive in two (0.6%) women, and 101 (29.7%) women had anti-T. gondii IgG and 70.3% were seronegative. PCR was positive in two IgM-positive women, and both isolates belonged to T. gondii carrying the GRA6 allele of lineage I. The risk of infection was significantly higher in women who had constant contact with cats and soil, and who were residents of rural areas. The two IgM-positive women were asymptomatic regarding acute toxoplasmosis. According to the results of the present study, the prevalence of toxoplasmosis in pregnant women in Urmia is similar to its prevalence in other areas in northwestern Iran, and despite the low prevalence of acute infection, it should not be ignored.

Antibody response to malaria vaccine candidates in pregnant women with Plasmodium falciparum and Schistosoma haematobium infections.

Malaria in pregnancy has severe consequences for the mother and foetus. Antibody response to specific malaria vaccine candidates (MVC) has been associated with a decreased risk of clinical malaria and its outcomes. We studied Plasmodium falciparum (Pf) and Schistosoma haematobium (Sh) infections and factors that could influence antibody responses to MVC in pregnant women. A total of 337 pregnant women receiving antenatal care (ANC) and 139 for delivery participated in this study. Pf infection was detected by qPCR and Sh infection using urine filtration method. Antibody levels against CSP, AMA-1, GLURP-R0, VAR2CSA and Pfs48/45 MVC were quantified by ELISA. Multivariable linear regression models identified factors associated with the modulation of antibody responses. The prevalence of Pf and Sh infections was 27% and 4% at ANC and 7% and 4% at delivery. Pf infection, residing in Adidome and multigravidae were positively associated with specific IgG response to CSP, AMA-1, GLURP-R0 and VAR2CSA. ITN use and IPTp were negatively associated with specific IgG response to GLURP-R0 and Pfs48/45. There was no association between Sh infection and antibody response to MVC at ANC or delivery. Pf infections in pregnant women were positively associated with antibody response to CSP, GLURP-R0 and AMA-1. Antibody response to GLURP-R0 and Pfs48/45 was low for IPTp and ITN users. This could indicate a lower exposure to Pf infection and low malaria prevalence observed at delivery.

[Use of LDBIO Diagnostics® TOXOPLASMA ICT IGG-IGM in association with Siemens Atellica® IM in toxoplasmosis serological screening]. / Place du test rapide LDBIO Diagnostics® TOXOPLASMA ICT IGG-IGM en complément de la sérologie Siemens Atellica® IM dans la stratégie diagnostique de la toxoplasmose.

According to French recommendations for serological screening of toxoplasmosis, some profiles must be confirmed by additional methods, extending the time taken to produce results. Thus, the Laborizon Bretagne technical platform in Nantes studied the place of the LDBIO Diagnostics® TOXOPLASMA ICT IGG-IGM (ICT) test in addition to Siemens Atellica® serology. IgG-/IgM+ and equivocal or weak positive IgG/IgM- (IgGEq/IgM-) profiles on Atellica® will be confirmed by ICT, Alinity® Abbott and Platelia® Biorad. Among the 66 IgGEq/IgM- profiles, the concordance is perfect between ICT and complementary techniques: 21 weak positives were confirmed positive, 8 equivocal were considered negative and 37 were confirmed positive. Concerning the 76 IgG-/IgM+ profiles, 68 are negative and 7 are positive by complementary techniques and ICT. One discordance was observed. The Atellica®/ICT combination allows excellent discrimination of IgG-/IgM+ and IgGEq/IgM serological profiles with consistent diagnostic orientation in 99.3% of cases. Only 1 sample was found to be discordant but required monitoring at 15 days. The observed performances are compatible with routine use. This test simplifies the analytical process, improves the time to obtain results, while guaranteeing an excellent level of quality.

Association between Toxoplasma gondii and gestational diabetes with regard to serum leptin and tumor necrosis factor alpha, a preliminary study.

Gestational diabetes (GDM), the onset of any degree of glucose intolerance during pregnancy, increases a wide range of adverse health outcomes for both the mother and the fetus. The aim of the present study was to evaluate the association of Toxoplasma gondii infection with GDM in a case-control study with regard to the levels of leptin and tumor necrosis factor alpha (TNF-α) as two inflammatory biomarkers. Fifty-one pregnant diabetic cases and 109 controls were selected from a prenatal care clinic of a general hospital in Shiraz, southern Iran during July-November 2020. Cases and controls were similar in age, gestational age and number of parturitions. The presence of IgG antibodies against T. gondii, and serum concentrations of leptin and TNF-α were determined by ELISA. Anti-Toxoplasma antibodies were detected in 25 subjects (15.6 %, 95 % CI: 9.9-21.3). Nine (18 %) diabetic cases were infected with Toxoplasma compared to 16 (15 %) healthy controls (P = 0.63). Level of leptin was higher (P = 0.07) while TNF-α was lower in diabetic cases compared to healthy controls (P = 0.08). When subjects were classified according to the combination of GDM and T. gondii, leptin was significantly lower in healthy (non-diabetic, non-infected) subjects compared to diabetics (P = 0.026), and TNF-α was higher in healthy subjects compared to Toxoplasma-infected diabetics (P = 0.032). These findings can be interpreted as both comorbidities being individually associated with increasing serum leptin and decreasing TNF-α concentrations, with modifying effects on each other. The present study opens a new perspective on GDM and its complex pathophysiological mechanism. Future research in this area is needed to better understand the underlying pathway for the development of GDM and the role of T. gondii and inflammatory biomarkers.

Seroprevalence and molecular detection of Toxoplasma gondii and Neospora caninum in beef cattle and goats in Hunan province, China.

BACKGROUND: Toxoplasma gondii and Neospora caninum are closely related protozoan parasites that are considered important causes of abortion in livestock, causing huge economic losses. Hunan Province ranks 12th in the production of beef and mutton in China. However, limited data are available on the seroprevalence, risk factors and molecular characterization of T. gondii and N. caninum in beef cattle and goats in Hunan province, China. METHODS: Sera of 985 beef cattle and 1147 goats were examined for the presence of specific antibodies against T. gondii using indirect hemagglutination test (IHAT) and anti-N. caninum IgG using competitive-inhibition enzyme-linked immunoassay assay (cELISA). Statistical analysis of possible risk factors was performed using PASW Statistics. Muscle samples of 160 beef cattle and 160 goats were examined for the presence of T. gondii DNA (B1 gene) and N. caninum DNA (Nc-5 gene) by nested PCR. The B1 gene-positive samples were genotyped at 10 genetic markers using the multilocus nested PCR-RFLP (Mn-PCR-RFLP). RESULTS: Specific IgG against T. gondii were detected in 8.3% (82/985) and 13.3% (153/1147) and against N. caninum in 2.1% (21/985) and 2.0% (23/1147) of the beef cattle and goats, respectively. Based on statistical analysis, the presence of cats, semi-intensive management mode and gender were identified as significant risk factors for T. gondii infection in beef cattle. Age was a significant risk factor for T. gondii infection in goats (P < 0.05), and age > 3 years was a significant risk factor for N. caninum infection in beef cattle (P < 0.05). PCR positivity for T. gondii was observed in three beef samples (1.9%; 3/160) and seven chevon samples (4.4%; 7/160). Genotyping of PCR positive samples identified one to be ToxoDB#10. The N. caninum DNA was observed in one beef sample (0.6%; 1/160) but was negative in all chevon samples. CONCLUSIONS: To our knowledge, this is the first large-scale serological and molecular investigation of T. gondii and N. caninum and assessment of related risk factors in beef cattle and goats in Hunan Province, China. The findings provide baseline data for executing prevention and control of these two important parasites in beef cattle and goats in China.

Anti-Plasmodium vivax merozoite surface protein 3 ϒ (PvMSP3 ϒ) antibodies upon natural infection.

Merozoite surface protein 3 of Plasmodium vivax (PvMSP3) contains a repertoire of protein members with unique sequence organization. While the biological functions of these proteins await elucidation, PvMSP3 has been suggested to be potential vaccine targets. To date, studies on natural immune responses to this protein family have been confined to two members, PvMSP3α and PvMSP3ß. This study analyzed natural IgG antibody responses to PvMSP3γ recombinant proteins derived from two variants: one containing insert blocks (CT1230nF) and the other without insert domain (NR25nF). The former variant was also expressed as two subfragment proteins: one encompassing variable domain I and insert block A (CT1230N) and the other spanning from insert block B to conserved block III (CT1230C). Serum samples were obtained from 246 symptomatic vivax malaria patients in Tak (n = 50) and Ubon Ratchathani (n = 196) Provinces. In total, 176 (71.5%) patients could mount antibodies to at least one recombinant PvMSP3γ antigen. IgG antibodies directed against antigens CT1230nF, CT1230N, CT1230C and NR25nF occurred in 96.6%, 61.4%, 71.6% and 68.2% of samples, respectively, suggesting the widespread occurrence of B-cell epitopes across PvMSP3γ. The rates of seropositivity seemed to correlate with the number of previous malaria episodes. Isotype analysis of anti-PvMSP3γ antibodies has shown predominant cytophilic subclass responses, accounting for 75.4-81.7% for IgG1 and 63.6-77.5% for IgG3. Comparing with previous studies in the same cohort, the numbers of serum samples reactive to antigens derived from P. vivax merozoite surface protein 9 (PvMSP9) and thrombospondin-related anonymous protein (PvTRAP) were higher than those to PvMSP3γ, being 92.7% and 87.0% versus 71.5%, respectively. Three (1.22%) serum samples were nonresponsive to all these malarial proteins. Nevertheless, the relevance of naturally acquired antibodies to PvMSP3γ in host protection requires further studies.

The Development of Toxoplasma gondii Recombinant Trivalent Chimeric Proteins as an Alternative to Toxoplasma Lysate Antigen (TLA) in Enzyme-Linked Immunosorbent Assay (ELISA) for the Detection of Immunoglobulin G (IgG) in Small Ruminants.

This study presents an evaluation of seventeen newly produced recombinant trivalent chimeric proteins (containing the same immunodominant fragment of SAG1 and SAG2 of Toxoplasma gondii antigens, and an additional immunodominant fragment of one of the parasite antigens, such as AMA1, GRA1, GRA2, GRA5, GRA6, GRA7, GRA9, LDH2, MAG1, MIC1, MIC3, P35, and ROP1) as a potential alternative to the whole-cell tachyzoite lysate (TLA) used in the detection of infection in small ruminants. These recombinant proteins, obtained by genetic engineering and molecular biology methods, were tested for their reactivity with specific anti-Toxoplasma IgG antibodies contained in serum samples of small ruminants (192 samples of sheep serum and 95 samples of goat serum) using an enzyme-linked immunosorbent assay (ELISA). The reactivity of six recombinant trivalent chimeric proteins (SAG1-SAG2-GRA5, SAG1-SAG2-GRA9, SAG1-SAG2-MIC1, SAG1-SAG2-MIC3, SAG1-SAG2-P35, and SAG1-SAG2-ROP1) with IgG antibodies generated during T. gondii invasion was comparable to the sensitivity of TLA-based IgG ELISA (100%). The obtained results show a strong correlation with the results obtained for TLA. This suggests that these protein preparations may be a potential alternative to TLA used in commercial tests and could be used to develop a cheaper test for the detection of parasite infection in small ruminants.

Extracellular vesicles derived from plasmodium-infected red blood cells alleviate cerebral malaria in plasmodium berghei ANKA-infected C57BL/6J mice.

RTS,S is the first malaria vaccine recommended for implementation among young children at risk. However, vaccine efficacy is modest and short-lived. To mitigate the risk of cerebral malaria (CM) among children under the age of 5, it is imperative to develop new vaccines. EVs are potential vaccine candidates as they obtain the ability of brain-targeted delivery and transfer plasmodium antigens and immunomodulators during infections. This study extracted EVs from BALB/c mice infected with Plasmodium yoelii 17XNL (P.y17XNL). C57BL/6J mice were intravenously immunized with EVs (EV-I.V. + CM group) or subcutaneously vaccinated with the combination of EVs and CpG ODN-1826 (EV + CPG ODN-S.C. + CM group) on days 0 and 20, followed by infection with Plasmodium berghei ANKA (P.bANKA) on day 20 post-second immunization. We monitored Parasitemia and survival rate. The integrity of the Blood-brain barrier (BBB) was examined using Evans blue staining.The levels of cytokines and adhesion molecules were evaluated using Luminex, RT-qPCR, and WB. Brain pathology was evaluated by hematoxylin and eosin and immunohistochemical staining. The serum levels of IgG, IgG1, and IgG2a were analyzed by enzyme-linked immunosorbent assay. Compared with those in the P.bANKA-infected group, parasitemia increased slowly, death was delayed (day 10 post-infection), and the survival rate reached 75 %-83.3 % in the EV-I.V. + ECM and EV + CPG ODN-S.C. + ECM groups. Meanwhile, compared with the EV + CPG ODN-S.C. + ECM group, although parasitemia was almost the same, the survival rate increased in the EV-I.V. + ECM group.Additionally, EVs immunization markedly downregulated inflammatory responses in the spleen and brain and ameliorated brain pathological changes, including BBB disruption and infected red blood cell (iRBC) sequestration. Furthermore, the EVs immunization group exhibited enhanced antibody responses (upregulation of IgG1 and IgG2a production) compared to the normal control group. EV immunization exerted protective effects, improving the integrity of the BBB, downregulating inflammation response of brain tissue, result in reduces the incidence of CM. The protective effects were determined by immunological pathways and brain targets elicited by EVs. Intravenous immunization exhibited better performance than subcutaneous immunization, which perhaps correlated with EVs, which can naturally cross BBB to play a better role in brain protection.

A phase IIa, randomized, double-blind, safety, immunogenicity and efficacy trial of Plasmodium falciparum vaccine antigens merozoite surface protein 1 and RTS,S formulated with AS02 adjuvant in healthy, malaria-naïve adults.

BACKGROUND: To improve the efficacy of Plasmodium falciparum malaria vaccine RTS,S/AS02, we conducted a study in 2001 in healthy, malaria-naïve adults administered RTS,S/AS02 in combination with FMP1, a recombinant merozoite surface-protein-1, C-terminal 42kD fragment. METHODS: A double-blind Phase I/IIa study randomized N = 60 subjects 1:1:1:1 to one of four groups, N = 15/group, to evaluate safety, immunogenicity, and efficacy of intra-deltoid half-doses of RTS,S/AS02 and FMP1/AS02 administered in the contralateral (RTS,S + FMP1-separate) or same (RTS,S + FMP1-same) sites, or FMP1/AS02 alone (FMP1-alone), or RTS,S/AS02 alone (RTS,S-alone) on a 0-, 1-, 3-month schedule. Subjects receiving three doses of vaccine and non-immunized controls (N = 11) were infected with homologous P. falciparum 3D7 sporozoites by Controlled Human Malaria Infection (CHMI). RESULTS: Subjects in all vaccination groups experienced mostly mild or moderate local and general adverse events that resolved within eight days. Anti-circumsporozoite antibody levels were lower when FMP1 and RTS,S were co-administered at the same site (35.0 µg/mL: 95 % CI 20.3-63), versus separate arms (57.4 µg/mL: 95 % CI 32.3-102) or RTS,S alone (62.0 µg/mL: 95 % CI: 37.8-101.8). RTS,S-specific lymphoproliferative responses and ex vivo ELISpot CSP-specific interferon-gamma (IFN-γ) responses were indistinguishable among groups receiving RTS,S/AS02. There was no difference in antibody to FMP1 among groups receiving FMP1/AS02. After CHMI, groups immunized with a RTS,S-containing regimen had âˆ¼ 30 % sterile protection against parasitemia, and equivalent delays in time-to-parasitemia. The FMP1/AS02 alone group showed no sterile immunity or delay in parasitemia. CONCLUSION: Co-administration of RTS,S and FMP1/AS02 reduced anti-RTS,S antibody, but did not affect tolerability, cellular immunity, or efficacy in a stringent CHMI model. Absence of efficacy or delay of patency in the sporozoite challenge model in the FMP1/AS02 group did not rule out efficacy of FMP1/AS02 in an endemic population. However, a Phase IIb trial of FMP1/AS02 in children in malaria-endemic Kenya did not demonstrate efficacy against natural infection. CLINICALTRIALS: gov identifier: NCT01556945.

Deciphering the epidemiological dynamics: Toxoplasma gondii seroprevalence in mainland China's food animals, 2010-2023.

Background: Toxoplasma gondii (T. gondii) is a significant protozoan pathogen among food animals. Despite the threat to public health by T. gondii infections, there's limited understanding of its seroprevalence and trends in food animals across mainland China. This study aimed to estimate the seroprevalence of T. gondii infections among swine, sheep, goats, chickens, and cattle in mainland China from 2010 to 2023. Methods: We searched cross-sectional studies published between 2010 and 2023 that reported the prevalence of T. gondii in food animals from databases including PubMed, Embase, Web of Science, China Biology Medicine Disc (CBM), China National Knowledge Infrastructure (CNKI), Wanfang data, and the China Science and Technology Journal Database (CQVIP). We performed subgroup analyses to explore the impact of different factors on the seroprevalence of T. gondii. Pooled estimates of T. gondii seroprevalence were calculated with a random-effects model. Results: An analysis of 184 studies involving 211985 animals revealed a T. gondii overall seroprevalence of 15.3% (95% CI: 13.1-17.8). Although the seroprevalence of food animals across mainland China was relatively stable from 2010 to 2023, notable variations were observed across different animal types and regions (P < 0.01), along with changes in geographical distribution. Sample type, detection method, animal age, and history of abortion were identified as key risk factors for T. gondii seroprevalence. Conclusion: The study conducted a meta-analysis on the seroprevalence of T. gondii in mainland China's Food Animals from 2010 to 2023, and identified key risk factors. These findings advance our understanding of T. gondii infection dynamics, offering critical insights for developing control strategies and guiding public health policies.