Vaccines against toxoplasma gondii : challenges and opportunities

Development of vaccines against Toxoplasma gondii infection in humans is of high priority, given the high burden of disease in some areas of the world like South America, and the lack of effective drugs with few adverse effects. Rodent models have been used in research on vaccines against T. gondii over the past decades. However, regardless of the vaccine construct, the vaccines have not been able to induce protective immunity when the organism is challenged with T. gondii, either directly or via a vector. Only a few live, attenuated T. gondii strains used for immunization have been able to confer protective immunity, which is measured by a lack of tissue cysts after challenge. Furthermore, challenge with low virulence strains, especially strains with genotype II, will probably be insufficient to provide protection against the more virulent T. gondii strains, such as those with genotypes I or II, or those genotypes from South America not belonging to genotype I, II or III. Future studies should use animal models besides rodents, and challenges should be performed with at least one genotype II T. gondii and one of the more virulent genotypes. Endpoints like maternal-foetal transmission and prevention of eye disease are important in addition to the traditional endpoint of survival or reduction in numbers of brain cysts after challenge

Immunogenicidad de una vacuna recombinante anti-HBs en trabajadores de la salud, del instituto de Medicina Legal de Colombia

Objective: To evaluate the immunogenicity of Hepavax-Gene recombinant hepatitis B vaccine in INML workers since the last administered doses. Methods: Cross-sectional study on 603 health workers with at least three administered recombinant vaccine doses. Antibody levels (anti-HBs) were measured using the ELISA technique during December 2000 and January 2001, taking into account that the last dose in the vaccination varied between 1 and 6 years. Results: A total of 344 men and 259 women with an age mean of 38.8±7.3 years were studied. Protection levels were found in 90.7% (?10 U/1), decreasing significantly with the worker's age (p less than 0.00 1) and with the vaccine last dose administration time (p less than 0.01). Health workers with four doses compared to those with three doses had a 4.7% higher protection (antibody median 209.8 vs. 130.07, p less than 0.001). No association was found with gender (p=0.463), smoking (p=0.331) and blood exposure (p=0.433). Multivariate analyses found that no protection associated only with age (40-44 years HR=2.37, Cl 95%:1.18,4.78 and ?45 years HR=3.58, Cl 95%: 1.83,6.99). Conclusions: Although Hepavax-Gene recombinant hepatitis B vaccine (anti-HBs) has a high effectiveness in the health workers (90.7%) it presents a decrease in protection levels related to a higher worker's age and along vaccine last dose administration time. © 2007 Corporación Editora Médica del Valle

Immunogenicidad de una vacuna recombinante anti-HBs en trabajadores de la salud, del instituto de Medicina Legal de Colombia

Objective: To evaluate the immunogenicity of Hepavax-Gene recombinant hepatitis B vaccine in INML workers since the last administered doses. Methods: Cross-sectional study on 603 health workers with at least three administered recombinant vaccine doses. Antibody levels (anti-HBs) were measured using the ELISA technique during December 2000 and January 2001, taking into account that the last dose in the vaccination varied between 1 and 6 years. Results: A total of 344 men and 259 women with an age mean of 38.8±7.3 years were studied. Protection levels were found in 90.7% (?10 U/1), decreasing significantly with the worker's age (p less than 0.00 1) and with the vaccine last dose administration time (p less than 0.01). Health workers with four doses compared to those with three doses had a 4.7% higher protection (antibody median 209.8 vs. 130.07, p less than 0.001). No association was found with gender (p=0.463), smoking (p=0.331) and blood exposure (p=0.433). Multivariate analyses found that no protection associated only with age (40-44 years HR=2.37, Cl 95%:1.18,4.78 and ?45 years HR=3.58, Cl 95%: 1.83,6.99). Conclusions: Although Hepavax-Gene recombinant hepatitis B vaccine (anti-HBs) has a high effectiveness in the health workers (90.7%) it presents a decrease in protection levels related to a higher worker's age and along vaccine last dose administration time. © 2007 Corporación Editora Médica del Valle

T regulatory lymphocytes: subpopulations, mechanism of action and importance in the control of autoimmunity

Immune regulation is both an important mechanism for maintaining immune system homeostasis and for the establishment of tolerance towards self antigens in order to prevent the development of autoimmune diseases. It also plays an important role in maintaining peripheral tolerance by controlling a small population of circulating T cells, called regulatory T cells (Treg), which seems to have migrated from the thymus during relatively late stages1. The term “regulatory T cells” refers to cells that activate or suppress the function of other cells. Apparently, controlling the development of autoimmune diseases (For instance, lupus, thyroiditis, type I diabetes and inflammatory bowel disease among others), graft rejection and may play a critical role in asthma and allergy. © 2011 Asociación Colombiana de Reumatologí

T regulatory lymphocytes: subpopulations, mechanism of action and importance in the control of autoimmunity

Immune regulation is both an important mechanism for maintaining immune system homeostasis and for the establishment of tolerance towards self antigens in order to prevent the development of autoimmune diseases. It also plays an important role in maintaining peripheral tolerance by controlling a small population of circulating T cells, called regulatory T cells (Treg), which seems to have migrated from the thymus during relatively late stages1. The term “regulatory T cells” refers to cells that activate or suppress the function of other cells. Apparently, controlling the development of autoimmune diseases (For instance, lupus, thyroiditis, type I diabetes and inflammatory bowel disease among others), graft rejection and may play a critical role in asthma and allergy. © 2011 Asociación Colombiana de Reumatologí

Toxoplasma gondii: Immunogenicity and protection by P30 peptides in a murine model

"Vaccines are promising for the control of toxoplasmosis. Here, we evaluated the immunogenicity of 17 peptides derived from SAG1 surface protein of Toxoplasma gondii in CH3 mice. Only 8 of 16 peptides induced specific antibodies. After a lethal challenge, only the vaccination with 4 of 17 peptides that were from the carboxy terminal end of the protein conferred significant survival. Our work shows that vaccination with peptides from the carboxy-terminal positions of SAG1 major surface protein of Toxoplasma protects mice against a lethal challenge. © 2006 Elsevier Inc. All rights reserved.

Toxoplasma gondii: Immunogenicity and protection by P30 peptides in a murine model

Vaccines are promising for the control of toxoplasmosis. Here, we evaluated the immunogenicity of 17 peptides derived from SAG1 surface protein of Toxoplasma gondii in CH3 mice. Only 8 of 16 peptides induced specific antibodies. After a lethal challenge, only the vaccination with 4 of 17 peptides that were from the carboxy terminal end of the protein conferred significant survival. Our work shows that vaccination with peptides from the carboxy-terminal positions of SAG1 major surface protein of Toxoplasma protects mice against a lethal challenge. © 2006 Elsevier Inc. All rights reserved

New U–Pb Baddeleyite Ages of Mafic Dyke Swarms of the West African and Amazonian Cratons: Implication for Their Configuration in Supercontinents Through Time

International audienc

A comprehensive review of Toxoplasma gondii biology and host-cell interaction: Challenges for a plant-based vaccine

Toxoplasmosisis a worldwide-distributed infection caused by Toxoplasma gondii, which causes a wide range of clinical syndromesin humans, mammals and birds. T. gondiiis considered a parasite of veterinary and medical importance, because it maycause abortion or congenital disease in its intermediate hosts. Despite theeconomic losses associated with T. gondiiinfection in farm animals and the socio-economic impact caused by this zoonoticdisease in the human population, there is no effective treatment available forhumans or animals able to eliminate the parasite from the host once the chronicinfection has been established. The only commercial vaccine is the S48 strainof attenuated tachyzoites for use in sheep. However, this vaccine causes sideeffects, has a short life time and induces a short-term immunity. So far, noacellular vaccine against toxoplasmosis has been commercialized. In fact, futurechallenges include the development of an effective vaccine to preventtoxoplasmosis. Most parasitologists and vaccinologists agree that futureefforts should be concentrated on developing multi-antigen vaccines and moreefficient delivery systems able to express heterologous proteins abundantly aswell as on searching for immunization schedules and adequate adjuvants toenhance the protective responses. To achieve this, platforms for the productionof acellular vaccines based on the use of plants can have an important role.Fil: Sander, Valeria Analía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Ángel, Sergio Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); ArgentinaFil: Clemente, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús). Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. Instituto de Investigaciones Biotecnológicas "Dr. Raúl Alfonsín" (sede Chascomús); Argentin