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.

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.

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.

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.

[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.

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.

Structure-guided design of VAR2CSA-based immunogens and a cocktail strategy for a placental malaria vaccine.

Placental accumulation of Plasmodium falciparum infected erythrocytes results in maternal anemia, low birth weight, and pregnancy loss. The parasite protein VAR2CSA facilitates the accumulation of infected erythrocytes in the placenta through interaction with the host receptor chondroitin sulfate A (CSA). Antibodies that prevent the VAR2CSA-CSA interaction correlate with protection from placental malaria, and VAR2CSA is a high-priority placental malaria vaccine antigen. Here, structure-guided design leveraging the full-length structures of VAR2CSA produced a stable immunogen that retains the critical conserved functional elements of VAR2CSA. The design expressed with a six-fold greater yield than the full-length protein and elicited antibodies that prevent adhesion of infected erythrocytes to CSA. The reduced size and adaptability of the designed immunogen enable efficient production of multiple variants of VAR2CSA for use in a cocktail vaccination strategy to increase the breadth of protection. These designs form strong foundations for the development of potent broadly protective placental malaria vaccines.

Prevalence and factors associated with Leishmania spp. and Toxoplasma gondii infections in apparently healthy horses in Eastern Spain.

Leishmaniasis and toxoplasmosis are two of the most common parasitic zoonoses. Leishmaniasis is endemic to 98 countries around the world, whereas toxoplasmosis is widely distributed throughout the world, causing significant health expenditure. Horses can play a relevant role in the transmission of the disease, being a silent reservoir, as clinical signs are not common. Serum samples from 166 horses living in eastern Spain (Mediterranean basin) were analysed to determine the presence of antibodies against Leishmania spp. and T. gondii by ELISA (Enzyme-linked Immunosorbent Assay.) The risk factors evaluated were the geographical area and the relative humidity and average temperature, and epidemiological factors such as sex, reproductive status, age, breed, morphotype, living with other domestic animals, use and access to the outdoors. Seroprevalence of Leishmania spp. and T. gondii infection was found 28.92%, and 16.27% respectively, whereas co-infection of the two parasites was found only in two males. Leishmania seroprevalence was high in castrated males and several mesodolichomorphic equine breeds used for teaching, as well as in outdoor animals. The most elevated seroprevalence was found in winter with higher levels of rainfall, whereas high seroprevalence of T. gondii was found in crossbreeding animals and those used for breeding. High seroprevalence of Leishmania spp. and T. gondii was found in horses of the Mediterranean basin. These data suggest that horses can act as a silent reservoir and that this species has high potential for transmission to humans, outdoor animals and in geographical areas with high average rainfall.

Absence of Anti-Babesia microti antibody in commercial intravenous immunoglobulin (IVIG).

BACKGROUND: Babesiosis is a worldwide emerging protozoan infection that is associated with a spectrum of disease severity from asymptomatic infection to severe organ damage and death. While effective treatment strategies are available, some immunocompromised patients experience severe acute and prolonged/relapsing illness due in part to an impaired host antibody response. Intravenous immunoglobulin (IVIG) has been used as an adjunctive therapy in some immunocompromised babesiosis patients, but its therapeutic effect is uncertain. We evaluated the presence of Babesia microti antibodies in commercial samples of IVIG. METHODS/PRINCIPLE FINDINGS: The presence of B. microti antibodies in commercial samples of IVIG were tested using an immunofluorescence assay. A subset of samples was then tested for B. microti antibodies using an enzyme linked immunosorbent assay. Out of 57 commercial IVIG samples tested using IFA, and 52 samples tested using ELISA, none were positive for B. microti antibodies. CONCLUSIONS: Commercially available IVIG may not be of therapeutic benefit for babesiosis patients. Additional sampling of IVIG for B. microti antibody and a clinical trial of babesiosis patients given IVIG compared with controls would provide further insight into the use of IVIG for the treatment of babesiosis.

Risk factors for Toxoplasma gondii infection in dogs: a serological survey.

BACKGROUND: Dogs, as well as a wide variety of other warm-blooded animals, act as intermediate host of Toxoplasma gondii. In dogs, most cases of toxoplasmosis are subclinical, although clinical disease has been sporadically reported. Beyond its role in diagnostic pathways, seropositivity also functions as a reflection of the parasite's spread within the dog's living environment. The aim of the present study was to evaluate the possible risk factor associated with seropositivity to T. gondii in dogs in Central-Northern Italy, analysing 120 dogs sera for the presence of IgG antibodies by indirect fluorescence antibody test (IFAT). RESULTS: The population examined was composed of 54.2% hunting dogs, 24.2% companion dogs, 14.2% truffle dogs and 7.5% watchdogs. Thirty-four (29.2%) dogs tested positive for T. gondii IgG, with titres ranging from 1:40 to 1:1280. Seroprevalence and antibodies titres were not related to dog gender, age or function. The logistic regression and ordered logistic regression results indicated that seroprevalence, and antibody titres were significantly higher in dogs cohabiting with cats, exhibiting coprophagy habits, and living constantly outdoors. Notably, the lifestyle factor showed the highest odds-ratios in the study: dogs living constantly outdoors were found to be at approximately 5 times greater risk of testing positive and having higher antibody titres compared to dogs living both indoors and outdoors. CONCLUSION: Both logistic and ordered logistic regression results support the key role of living with cats, engaging in coprophagy behaviours, and maintaining an outdoor lifestyle in increasing the risk of T. gondii infection in dogs. These identified risk factors collectively suggest that both ingesting oocysts, as observed through cat cohabitation and coprophagy, and engaging in predatory behaviours, as possible for outdoor living dogs, are indicating likely sources of T. gondii infection in this host species.

Seroprevalence and risk factors of Toxoplasma gondii in sheep and goats of North West Province, South Africa.

BACKGROUND: The protozoan parasite Toxoplasma gondii causes toxoplasmosis, one of the most prevalent parasitic zoonotic diseases with significant economic and public health implications worldwide. Infection with the parasite has a significant adverse effect on sheep and goat production and can frequently go undetected in the herd, resulting in abortions and weak or dead offspring. Although there are few studies on seroprevalence and risk factors associated with T. gondii infections in livestock in other provinces of South Africa, there is no data in the North West province. Therefore, a cross-sectional study was conducted to investigate the seroprevalence of T. gondii and risk factors associated with exposure in sheep and goats of the North West province of South Africa. Sera from 439 livestock (164 sheep and 285 goats) were collected and analysed for the presence of T. gondii IgG antibodies using indirect ELISA (Enzyme-linked immunosorbent assay). An assessment of potential risk factors in farms associated with seropositivity was also conducted using a structured questionnaire. RESULTS: Out of the 439 tested sheep and goats, 13.9% (61/439) were positive for IgG antibodies against T. gondii. Sheep and goats had seroprevalences of 19.5% (32/164) and 10.5% (29/275) respectively. In the multivariable logistic regression model, the risk of acquiring T. gondii was significantly higher in the mixed breed [Odds ratio (OR) = 71.07; 95% confidence interval (CI): 266.8-1893.1; p < 0.011)] animals than white dorper sheep and in farms that burn or bury aborted material (OR = 42.04; CI: 179.9-982.5; p = 0.020) compared to those that only burn aborted material. The risk was lower for the farms in Kagisano-Molopo (OR = 0.00; CI: 0.0-25.4; p = 0.015) and Mahikeng (OR = 0.00; CI: 0.0-4.9; p < 0.001) local municipalities than Greater Taung local municipality, and for the animals that drink water from dams (OR = 0.03; CI: 0.2-58.8; p = 0.021) than those that drink from boreholes. CONCLUSION: The seroprevalence and risk factors associated with transmission observed show that T. gondii infection is widespread in sheep and goats of the North West province.

Prevalence and associated risk factors of anti-Coxiella burnetii antibodies in dairy cattle herds using bulk tank milk analysis in Kabylia area, north Algeria.

Coxiella burnetii, or Q fever agent, has notable implications for human and livestock health. Infections in cattle primarily manifest through reproductive issues where infected animals shed the bacterium in birth fluids, placental tissues, and milk, serving as potential sources of transmission. Bovine herds become reservoirs, contributing to the environmental contamination of farming areas. Comprehensive studies on the prevalence, transmission routes, and associated risk factors among cattle contribute to the development of effective control strategies, ultimately safeguarding both livestock and public health.Here we determine the prevalence of Coxiella burnetii antibodies against in dairy cattle farms from Kabylia (northern Algeria) and identify the associated risk factors. Bulk tank milk samples from 184 farms were analyzed by indirect ELISA technique, 49 of them were tested positive which corresponds to a prevalence rate of 26.63% (95% CI 20.25-33.01%). Multivariate analysis by logistic regression showed that the risk factors associated with detection of anti-Coxiella burnetii antibodies are: cohabitation of cattle with small ruminants(OR = 3.74 95% CI [1.41-8.92]), exposure to prevailing winds (OR = 5.12 95% CI [2.11-13.45]), and the veterinarian visits frequency(OR = 5.67 95% CI [2.55-13.60]). These findings underscore the susceptibility of dairy cattle to Q fever in the Kabylia region, highlighting practices that pose risks. We recommend the implementation of hygienic measures and adherence to proper farming conditions to mitigate the transmission of Q fever and reduce the associated zoonotic risk.

Non-clinical toxicity and immunogenicity evaluation of a Plasmodium vivax malaria vaccine using Poly-ICLC (Hiltonol®) as adjuvant.

Malaria caused byPlasmodium vivaxis a pressing public health problem in tropical and subtropical areas.However, little progress has been made toward developing a P. vivaxvaccine, with only three candidates being tested in clinical studies. We previously reported that one chimeric recombinant protein (PvCSP-All epitopes) containing the conserved C-terminus of the P. vivax Circumsporozoite Protein (PvCSP), the three variant repeat domains, and aToll-like receptor-3 agonist,Poly(I:C), as an adjuvant (polyinosinic-polycytidylic acid, a dsRNA analog mimicking viral RNA), elicits strong antibody-mediated immune responses in mice to each of the three allelic forms of PvCSP. In the present study, a pre-clinical safety evaluation was performed to identify potential local and systemic toxic effects of the PvCSP-All epitopes combined with the Poly-ICLC (Poly I:C plus poly-L-lysine, Hiltonol®) or Poly-ICLC when subcutaneously injected into C57BL/6 mice and New Zealand White Rabbits followed by a 21-day recovery period. Overall, all observations were considered non-adverse and were consistent with the expected inflammatory response and immune stimulation following vaccine administration. High levels of vaccine-induced specific antibodies were detected both in mice and rabbits. Furthermore, mice that received the vaccine formulation were protected after the challenge with Plasmodium berghei sporozoites expressing CSP repeats from P. vivax sporozoites (Pb/Pv-VK210). In conclusion, in these non-clinical models, repeated dose administrations of the PvCSP-All epitopes vaccine adjuvanted with a Poly-ICLC were immunogenic, safe, and well tolerated.

Comparative evaluation of four rapid diagnostic tests that detect human Trypanosoma cruzi-specific antibodies to support diagnosis of Chagas Disease in urban population of Argentina.

BACKGROUND: Chagas disease (CD), caused by the parasite Trypanosoma cruzi, is the most important endemic anthropozoonosis in Argentina. Since 2010, the World Health Organization has highlighted the urgent need to validate diagnostic systems that allow rapid detection of T. cruzi, infection in primary healthcare centers. Serological rapid diagnostic tests (RDTs) for T. cruzi, infection could be used to improve case management, as RDTs do not require specialized laboratories or highly trained staff to use them. We aimed to generate unbiased performance data of RDTs in Argentina, to evaluate their usefulness for improving T. cruzi, diagnosis rates. METHODS AND PRINCIPAL FINDINGS: This is a retrospective, laboratory-based, diagnostic evaluation study to estimate the clinical sensitivity/specificity of four commercially available RDTs for T. cruzi, using the Chagas disease diagnostic algorithm currently used in Argentina as the reference standard. In total, 400 serum samples were tested, 200 from individuals with chronic T. cruzi infection and 200 from individuals not infected with T. cruzi. All results were registered as the agreement of at least two operators who were blinded to the reference standard results. The sensitivity estimates ranged from 92.5-100% (95% confidence interval (CI) lower bound 87.9-98.2%); for specificity, the range was 76-96% (95% CI lower bound 69.5-92.3%). Most RDTs evaluated showed performances comparable with the reference standard method, showing almost perfect concordance (Kappa 0.76-0.92). CONCLUSIONS: Our study demonstrates that, under controlled laboratory conditions, commercially available RDTs for CD have a performance comparable to the Argentinian diagnostic algorithm, which is based on laboratory-based serological tests. For the next stage of our work, the RDTs will be evaluated in real-world settings.

Observational longitudinal study on Toxoplasma gondii infection in fattening beef cattle: serology and associated haematological findings.

Toxoplasmosis, caused by the protozoan parasite Toxoplasma gondii, is a globally distributed zoonotic infection with significant implications for human and animal health. This study investigated the prevalence of T. gondii infection in a population of beef cattle at three different stages of their productive lifespan and examined the impact of T. gondii serological status on blood parameters. A commercial beef fattening unit in Italy was the setting for this research, which involved a biosecurity assessment upon cattle arrival, blood sampling at three time points and Toxoplasma-specific serological testing using indirect fluorescent antibody tests (IFAT). Results revealed a dynamic pattern of T. gondii seropositivity in cattle, with an initial prevalence of 30.6% at arrival (T0) that increased to 44.6% at 14 days (T1) and then decreased slightly to 39.3% at slaughter after 5 months (T2). Interestingly, seroconversion was observed during the study, indicating ongoing infections, and antibody waning occurred in some animals. In terms of blood parameters, seropositive cattle exhibited significantly lower mean corpuscular volume (MCV) and a higher neutrophil-lymphocyte (N/L) ratio, suggesting an activation of the innate immune response. Furthermore, cattle with higher antibody titres displayed higher neutrophil counts. However, all blood parameters with a statistical significance were within the reference range. This study provides for the first time a longitudinal investigation on the serological status for T. gondii in naturally exposed beef cattle. These findings provide valuable insights into the clinico-pathological aspects of natural T. gondii exposure in cattle and underscore the importance of monitoring and managing T. gondii infection in livestock production systems.

Protective efficacy of recombinant Toxoplasma gondii dense granule protein 15 against toxoplasmosis in C57BL/6 mice.

Toxoplasma gondii is a pervasive protozoan parasite that is responsible for significant zoonoses. A wide array of vaccines using different effector molecules of T. gondii have been studied worldwide to control toxoplasmosis. None of the existing vaccines are sufficiently effective to confer protective immunity. Among the different Toxoplasma-derived effector molecules, T. gondii dense granule protein 15 from the type II strain (GRA15 (II)) was recently characterized as an immunomodulatory molecule that induced host immunity via NF-κB. Therefore, we assessed the immunostimulatory and protective efficacy of recombinant GRA15 (II) (rGRA15) against T. gondii infection in a C57BL/6 mouse model. We observed that rGRA15 treatment increased the production of IL-12p40 from mouse peritoneal macrophages in vitro. Immunization of mice with rGRA15 induced the production of anti-TgGRA15-specific IgG, IgG1 and IgG2c antibodies. The rGRA15-sensitized spleen cells from mice inoculated with the same antigen strongly promoted spleen cell proliferation and IFN-γ production. Immunization with rGRA15 significantly enhanced the survival rate of mice and dramatically decreased parasite burden in mice challenged with the Pru (type II) strain. These results suggested that rGRA15 triggered humoral and cellular immune responses to control infection. However, all of the immunized mice died when challenged with the GRA15-deficient Pru strain or the RH (type I) strain. These results suggest that GRA15 (II)-dependent immunity plays a crucial role in protection against challenge infection with the type II strain of T. gondii. This study is the first report to show GRA15 (II) as a recombinant vaccine antigen against Toxoplasma infection.

Atypical memory B cell frequency correlates with antibody breadth and function in malaria immune adults.

Clinical immunity to malaria develops slowly after repeated episodes of infection and antibodies are essential in naturally acquired immunity against malaria. However, chronic exposure to malaria has been linked to perturbation in B-cell homeostasis with the accumulation of atypical memory B cells. It is unclear how perturbations in B cell subsets influence antibody breadth, avidity, and function in individuals naturally exposed to malaria. We show that individuals living in high malaria transmission regions in Ghana have higher Plasmodium falciparum merozoite antigen-specific antibodies and an increased antibody breadth score but lower antibody avidities relative to low transmission regions. The frequency of circulating atypical memory B cells is positively associated with an individual's antibody breadth. In vitro growth inhibition is independent of the ability to bind to free merozoites but associated with the breadth of antibody reactivity in an individual. Taken together, our data shows that repeated malaria episodes hamper the development of high avid antibodies which is compensated for by an increase in antibody breadth. Our results provide evidence to reinforce the idea that in regions with high malaria prevalence, repeated malaria infections lead to the broadening of antibody diversity and the continued presence of atypical memory B cell populations.

Sero-epidemiological investigation on Toxoplasma gondii infection in Apennine wolf (Canis lupus italicus) and wild boar (Sus scrofa) in Italy.

BACKGROUND: The wild boar (Sus scrofa) and the Apennine wolf (Canis lupus italicus) are two wild species that have both increased their presence in the Italian territory, albeit in varying numbers. They can be occasionally found in peri-urban areas as well. Both of these species can serve as intermediate hosts for Toxoplasma gondii, as they can become infected either through the consumption of oocysts found in water, soil, or on vegetables, or through the ingestion of meat containing bradyzoites. Consequently, these animals can be regarded as key indicators of Toxoplasma presence in the wild or peri-urban environment. In our study, we examined a total of 174 wild boar meat juice and 128 wolf sera from Italy for the detection of T. gondii IgG using the indirect fluorescent antibody test (IFAT). RESULTS: The results showed that 40 (22.6%) of the wild boar meat juice and 34 (26.6%) of the wolf serum samples tested positive. Interestingly, there were no significant differences in seropositivity with respect to gender, age group, or the region of origin in both species. CONCLUSIONS: Overall the results indicate a moderate exposure in both the species under investigation, highlighting the spread of T. gondii in sylvatic and periurban environments. The prevalence of T. gondii in wild boar is consistent with findings from other studies conducted in Europe. Our study, with a considerably larger sample size compared to the available research in European context, provides valuable data on the seroprevalence of T. gondii in wolves.

Comparison of immunological and molecular methods for laboratory diagnosis of ocular toxoplasmosis in blood, serum and tears in Brazil.

Ocular toxoplasmosis (OT) is caused by protozoan T. gondii. Ophthalmological examination is considered the gold standard for OT diagnosis, and laboratory tests are used for diagnostic confirmation. However, these tests can present different results, which change depending on their basis, on sample type and on patients' clinical alteration. Thus, the aim of the present study is to assess immunodiagnostic and molecular techniques applied in blood, serum and tear fluid to diagnose T. gondii infection in patients seen at an Ophthalmology Clinic. In total, 160 patients were included in the study, 40 of them had OT with active lesions (G1); 40 had OT with healed lesions (G2), 40 had non-toxoplasmic uveitis (G3) and 40 had no ocular alterations (G4). Serum samples were subjected to Immunoenzymatic Assay (ELISA) and to Indirect Immunofluorescence Reaction (IFAT) to search for anti-T. gondii IgM and IgG. Tear fluid samples were analyzed through ELISA for IgA research. All blood and tear fluid samples were subjected to conventional polymerase chain reaction (cPCR) and in a Nested PCR model for T. gondii DNA amplification with targets B1, GRA7 and REP 529. IgG and IgM anti-T. gondii was detected in serum samples from 106 and 15 patients, respectively, when combining ELISA and IFAT results. Anti-T.gondii IgA antibodies were detected in 9.2% of the tear material. Nested PCR with GRA7 target showed higher positivity in blood samples (24.4%); Nested PCR with B1 target showed a higher frequency of positivity in tears (15%). Biological samples of patients with active lesions showed the highest positivity frequencies in all immunodiagnostic assays, as well as in most PCR models. The present results highlighted the need of associating techniques with different fundamentals to confirm OT diagnosis. Furthermore, further tear fluid analyses should be performed to validate this biological material as lesser invasive alternative for the more accurate OT diagnosis.

A Diversity Covering (DiCo) Plasmodium vivax apical membrane antigen-1 vaccine adjuvanted with RFASE/RSL10 yields high levels of growth-inhibitory antibodies.

Plasmodium vivax malaria is increasingly recognized as a major global health problem and the socio-economic impact of P.vivax-induced burden is huge. Vaccine development against P. vivax malaria has been hampered by the lack of an in vitro culture system and poor access to P. vivax sporozoites. The recent generation of Plasmodium falciparum parasites that express a functional P. vivax AMA1 molecule has provided a platform for in vitro evaluation of PvAMA1 as a potential blood stage vaccine. Three so-called PvAMA1 Diversity Covering (DiCo) proteins were designed to assess their potential to induce a functional and broad humoral immune response to the polymorphic PvAMA1 molecule. Rabbits were immunized with the mixture of three, Pichia-produced, PvAMA1 DiCo proteins, as well as with 2 naturally occurring PvAMA1 alleles. For these three groups, the experimental adjuvant raffinose fatty acid sulfate ester (RFASE) was used, while in a fourth group the purified main mono-esterified constituent (RSL10) of this adjuvant was used. Animals immunized with the mixture of the three PvAMA1 DiCo proteins in RFASE showed high anti-PvAMA1 antibody titers against three naturally occurring PvAMA1variants while also high growth-inhibitory capacity was observed against P. falciparum parasites expressing PvAMA1. This supports further clinical development of the PvAMA1 DiCo mixture as a potential malaria vaccine. However, as the single allele PvAMA1 SalI-group showed similar characteristics in antibody titer and inhibition levels as the PvAMA1 DiCo mixture-group, this raises the question whether a mixture is really necessary to overcome the polymorphism in the vaccine candidate. RFASE induced strong humoral responses, as did the animals immunized with the purified component, RSL10. This suggests that RSL10 is the active ingredient. However, one of the RSL10-immunized animal showed a delayed response, necessitating further research into the clinical development of RSL10.