Plasmodium falciparum liver stage antigen-1 (PfLSA-1) is one of the few antigens expressed exclusively in liver stage parasites. In this study, we evaluated the antibody responses against recombinant PfLSA-1 in naturally infected individuals in Myanmar. High levels of antibody responses (70.7%) were detected in 82 serum samples from 116 infected individuals, and IgG responses to PfLSA-1 principally composed of responses of IgG1 and IgG3 subclasses. These results show that PfLSA-1 elicits effective antibody responses in individuals infected with P. falciparum, and thus it could be not only an attractive candidate protein for vaccine development, but also a useful antigen for serodiagnosis of the infection.
Animals ; Antibodies, Protozoan/*blood/immunology ; Antigens, Protozoan/*immunology ; Humans ; Immunoglobulin G/blood ; Malaria, Falciparum/blood/epidemiology/*immunology ; Myanmar/epidemiology

The diagnosis of cryptosporidiosis has been carried out using coprologic techniques in the Republic of Korea. However, antibody responses to Cryptosporidium have rarely been studied. Serum antibodies from HIV-positive/oocyst-positive Korean patients recognized significantly 31 and 27 kDa antigens, and HIV-negative/oocyst-positive individuals clearly reacted to 15/17 kDa antigens. Compared with oocyst-positive cases, 18.7% and 75.8% of sera from HIV-positive patients reacted to 31 and 27 kDa antigens. Only 11.1% of HIV-negative individuals reacted to 15/17 kDa. Based on these findings, serum antibody responses were different between HIV-positive and HIV-negative individuals infected with Cryptosporidium, and it is suggested that HIV-positive patients are more frequently exposed to C. parvum compared to HIV-negative individuals.
AIDS-Related Opportunistic Infections/blood/*immunology ; Adult ; Aged ; Animals ; Antibodies, Protozoan/*blood/immunology ; *Antibody Formation ; Antigens, Protozoan/chemistry/*immunology ; Blotting, Western/methods ; Cryptosporidiosis/blood/*immunology ; Feces/parasitology ; Female ; Humans ; Korea ; Male ; Middle Aged ; Protozoan Proteins/chemistry/immunology

OBJECTIVETo characterize the immune response induced by SAG1 encoding plasmid combined with IL-2 gene adjuvant in mice and to assess the protective effect of this vaccination against toxoplasmosis.

METHODSMice were co-injected intramuscularly with plasmid encoding Toxoplasma gondii SAG1 plus murine IL-2 expression vector at a dose of 100 microg. Booster immunizations were employed 2 more times at 3-week interval. As controls, mice were inoculated with PBS or empty plasmid pcDNA3. Humoral and cellular responses were assayed using ELISA for the determination of Ab, Ab isotype and IFN-gamma, as well as IL-4. To detect the integration and dissemination of DNA in the injected mice, PCR and in situ hybridization were performed. All mice were then infected with highly virulent RH tachyzoites of Toxoplasma gondii intraperitoneally.

RESULTSSignificant increases in specific IgG levels were observed in mice after immunization three times with SAG1 expression plasmid. With respect to the IgG isotype, co-inoculation of IL-2 expression plasmid enhanced the level of IgG2a and the production of IFN-gamma. Challenging mice by vaccinating with combined plasmids with RH tachyzoites resulted in prolonged survival.

CONCLUSIONHumoral and cytokine responses elicited by SAG1 DNA immunization can be modulated by co-inoculation with IL-2 expression plasmid. The use of DNA vaccine in combination with an appropriate cytokine gene to prevent T. gondii infection warrants further investigation.

Animals ; Antibodies, Protozoan ; blood ; Antigens, Protozoan ; Cytokines ; biosynthesis ; Female ; Immunization ; Immunoglobulin G ; blood ; classification ; Interleukin-2 ; genetics ; Mice ; Protozoan Proteins ; genetics ; Protozoan Vaccines ; immunology ; Toxoplasma ; immunology ; Toxoplasmosis, Animal ; prevention & control ; Vaccines, DNA ; immunology

To control coccidiosis without using prophylactic medications, a DNA vaccine targeting the gametophyte antigen Gam56 from Eimeria maxima in chickens was constructed, and the immunogenicity and protective effects were evaluated. The ORF of Gam56 gene was cloned into an eukaryotic expression vector pcDNA3.1(zeo)+. Expression of Gam56 protein in COS-7 cells transfected with recombinant plasmid pcDNA-Gam56 was confirmed by indirect immunofluorescence assay. The DNA vaccine was injected intramuscularly to yellow feathered broilers of 1-week old at 3 dosages (25, 50, and 100 microg/chick). Injection was repeated once 1 week later. One week after the second injection, birds were challenged orally with 5x10(4) sporulated oocysts of E. maxima, then weighed and killed at day 8 post challenge. Blood samples were collected and examined for specific peripheral blood lymphocyte proliferation activity and serum antibody levels. Compared with control groups, the administration of pcDNA-Gam56 vaccine markedly increased the lymphocyte proliferation activity (P<0.05) at day 7 and 14 after the first immunization. The level of lymphocyte proliferation started to decrease on day 21 after the first immunization. A similar trend was seen in specific antibody levels. Among the 3 pcDNA-Gam56 immunized groups, the median dosage group displayed the highest lymphocyte proliferation and antibody levels (P<0.05). The median dosage group had the greatest relative body weight gain (89.7%), and the greatest oocyst shedding reduction (53.7%). These results indicate that median dosage of DNA vaccine had good immunogenicity and immune protection effects, and may be used in field applications for coccidiosis control.
Animals ; Antibodies, Protozoan/blood ; Antigens, Protozoan/genetics/*immunology ; Cell Proliferation ; Chickens ; Coccidiosis/immunology/pathology/*prevention & control ; Disease Models, Animal ; Eimeria/genetics/*immunology ; Injections, Intramuscular ; Lymphocytes/immunology ; Protozoan Vaccines/administration & dosage/genetics/*immunology ; Vaccination/methods ; Vaccines, DNA/administration & dosage/genetics/*immunology

Serologic tests are widely accepted for diagnosing Toxoplasma gondii but purification and standardization of antigen needs to be improved. Recently, surface tachyzoite and bradyzoite antigens have become more attractive for this purpose. In this study, diagnostic usefulness of 3 recombinant antigens (SAG1, SAG2, and SAG3) were evaluated, and their efficacy was compared with the available commercial ELISA. The recombinant plasmids were transformed to JM109 strain of Escherichia coli, and the recombinants were expressed and purified. Recombinant SAG1, SAG2, and SAG3 antigens were evaluated using different groups of sera in an ELISA system, and the results were compared to those of a commercial IgG and IgM ELISA kit. The sensitivity and specificity of recombinant surface antigens for detection of anti-Toxoplasma IgG in comparison with commercially available ELISA were as follows: SAG1 (93.6% and 92.9%), SAG2 (100.0% and 89.4%), and SAG3 (95.4% and 91.2%), respectively. A high degree of agreement (96.9%) was observed between recombinant SAG2 and commercial ELISA in terms of detecting IgG anti-Toxoplasma antibodies. P22 had the best performance in detecting anti-Toxoplasma IgM in comparison with the other 2 recombinant antigens. Recombinant SAG1, SAG2, and SAG3 could all be used for diagnosis of IgG-specific antibodies against T. gondii.
Antibodies, Protozoan/*blood ; Antigens, Protozoan/diagnostic use/*genetics ; Enzyme-Linked Immunosorbent Assay ; Humans ; Immunoglobulin G/blood ; Immunoglobulin M/blood ; Membrane Glycoproteins/*genetics ; Protozoan Proteins/*genetics ; Recombinant Proteins/diagnostic use/immunology ; Sensitivity and Specificity ; Toxoplasma/immunology ; Toxoplasmosis/blood/*diagnosis

A Cryptosporidium parvum sporozoite and oocyst lambda gt11 cDNA library was screened with a hyperimmune rabbit serum that was developed against insoluble fragments of ultrasonicated oocysts. A clone named Cp22.4.1 encoding a protein of 231 amino acids with 4 zinc-finger domains characterized by a Cys-X2-Cys-X4-His-X4-Cys motif was isolated and characterized. There was a complete match between the sequencing data of the coding region of Cp22.4.1 and the corresponding gene at chromosomal level. Cloning in a pBAD-TOPO-TA expression vector permitted to evaluate the antigenicity of the recombinant His-tagged antigen. This antigen was recognized by 2 out of 5 sera from Cryptosporidium immune calves and not by sera from parasite naive animals.
Amino Acid Sequence ; Animals ; Antibodies, Protozoan/*blood ; Antigens, Protozoan/chemistry/*immunology ; Base Sequence ; Cattle/*immunology ; Cryptosporidium parvum/*immunology ; Molecular Sequence Data ; Protozoan Proteins/chemistry/genetics ; Rabbits ; Recombinant Proteins ; Zinc Fingers/genetics/*immunology

Field rodents involved in ecological food chains and which are the prey of carnivores in the natural environment may serve as reservoir hosts for Toxoplasma gondii infection in humans, however, no data has been published to date in Korea. A total of 1,008 Apodemus agrarius, a dominant species of field rodents in Korea, were trapped at various locations around the country, and their serum antibody (IgG) levels to T. gondii were examined by ELISA. The mean absorbance was 0.11, and fifteen samples (1.49%) showed positive titers from 0.18 to 0.59. The seropositive samples were analyzed by immunoblot. Five of them showed reactive bands to T. gondii water soluble antigens of 30, 35, and 43 kDa. This immunoblot analysis showed very similar patterns to that obtained using sera of experimentally infected mice with T. gondii. The present study presents indirect evidence of the existence of T. gondii in field rodents in Korea.
Animal ; Antibodies, Protozoan/blood* ; Antigens, Protozoan/immunology ; Enzyme-Linked Immunosorbent Assay ; Immunoblotting ; Molecular Weight ; Muridae/parasitology* ; Seroepidemiologic Studies ; Toxoplasma/isolation & purification* ; Toxoplasma/immunology

Animals ; Antibodies, Protozoan ; analysis ; Antigens, Protozoan ; analysis ; Asthma ; blood ; parasitology ; Child ; Child, Preschool ; Female ; Humans ; Infant ; Male ; Toxoplasma ; immunology ; Toxoplasmosis ; blood

Recombinant antigenic proteins of Toxoplasma gondii are alternative source of antigens which are easily obtainable for serodiagnosis of toxoplasmosis. In this study, highly antigenic secretory organellar proteins, dense granular GRA2 and GRA3, rhoptrial ROP2, and micronemal MIC2, were analyzed by bioinformatics approach to express as water-soluble forms of antigenic domains. The transmembrane region and disorder tendency of 4 secretory proteins were predicted to clone the genes into pGEX-4T-1 vector. Recombinant plasmids were transformed into BL21 (DE3) pLysS E. coli, and GST fusion proteins were expressed with IPTG. As a result, GST fusion proteins with GRA225-105, GRA339-138, ROP2324-561, and MIC21-284 domains had respectively higher value of IgG avidity. The rGST-GRA225-105 and rGST-GRA339-138 were soluble, while rGST-ROP2324-561 and rGST-MIC21-284 were not. GRA231-71, intrinsically unstructured domain (IUD) of GRA2, was used as a linker to enhance the solubility. The rGST-GRA231-71-ROP2324-561, a chimeric protein, appeared to be soluble. Moreover, rGST-GRA231-71-MIC21-284 was also soluble and had higher IgG avidity comparing to rGST-MIC21-284. These 4 highly expressed and water-soluble recombinant antigenic proteins may be promising candidates to improve the serodiagnosis of toxoplasmosis in addition to the major surface antigen of SAG1.
Animals ; Antibodies, Protozoan/immunology ; Antibody Affinity ; Antigens, Protozoan/chemistry/*diagnostic use/genetics/immunology ; *Gene Expression ; Immunoglobulin G/blood/immunology ; Mice, Inbred BALB C ; Recombinant Proteins/chemistry/*diagnostic use/genetics/immunology ; Serologic Tests/methods ; Solubility ; Toxoplasma/genetics/immunology/*metabolism ; Toxoplasmosis/diagnosis

OBJECTIVETo study the changes and significance of lymphocyte sunsets and serum interferon-γ (IFN-γ) levels in children with toxoplasma infection.

METHODSThirty-four children who were newly diagnosed with toxoplasma infection (TOX-IgM+ group) between January 2011 and April 2014, 12 children who had ever been diagnosed with toxoplasma infection (TOX-IgG+ group), and 54 healthy children (control group) were enrolled. The percentages of CD4+, CD8+, CD19+ and NK cells in peripheral blood lymphocytes were detected by flow cytometry. Serum levels of IFN-γ were measured using ELISA.

RESULTSThe percentages of CD4+ cells and the CD4+/CD8+ ratio in the TOX-IgM+ group were significantly lower than in the TOX-IgG+ and control groups, while the percentages of CD8+ and NK cells and serum IFN-γ levels were significantly higher than in the other two groups (P<0.05). The TOX-IgG+ group had higher serum IFN-γ levels than the control group (P<0.05). There was a positive correlation between the percentage of CD8+ cells and serum IFN-γ levels in the TOX-IgM+ group (r=0.756; P<0.05).

CONCLUSIONSCD4+, CD8+ and NK cells may play important roles in the resistance against toxoplasma infection by promoting the secretion of cytokines.

Antibodies, Protozoan ; blood ; CD4-CD8 Ratio ; Child, Preschool ; Female ; Humans ; Immunoglobulin G ; blood ; Immunoglobulin M ; blood ; Infant ; Interferon-gamma ; blood ; Lymphocyte Subsets ; immunology ; Male ; Toxoplasma ; immunology