Electrophoretic Patterns of Toxoplasma gondii Excreted/Secreted Antigens and Their Role in Induction of the Humoral Immune Response

Abstract

Background:Toxoplasma gondii is an obligatory intracellular protozoan parasite on which studies are pending regarding production of vaccine. To date, the production of human vaccine has not been successful where approximately one third of the world’s population is thought to be infected with T. gondii.Objectives:The present study was designed to compare the electrophoretic patterns of T. gondii excreted/secreted antigens (ESAs) and determine their role in the stimulation of the humoral immune response.Materials and Methods:T. gondii ESAs were prepared from cell cultures (albino rat fibroblast) and cell-free mediums (RPMI-1640). Next, the SDS-PAGE technique was used for comparing molecular weights of the antigens. Forty C57BL/6 mice were divided randomly into four groups (n = 10). Immunization was performed subcutaneously at an interval of 2 weeks in two groups by injecting 100 µg of each of the above-mentioned antigens. Two groups, as negative control, also received fibroblast lysate proteins or adjuvant separately. All of the groups were then challenged with the T. gondii RH strain. Serum samples were collected from all mice and measured by immunoblotting technique for detection of immunogenic antigens.Results:The electrophoretic mobility of the prepared antigens/proteins from cell culture, cell-free media, Fibroblast Lysate Proteins and Toxoplasma Lysate Antigens (TLA) showed 13, 12, 8 and 8 bands, respectively. The case groups, in challenge with T. gondii (RH strain), showed more survival prolongation than the control groups. Furthermore, the survival period was identical for both case groups with a tendency for slightly higher survival of mice receiving ESA from cell-free medium. Analysis of sera by immunoblotting also revealed one band of 65 KDa in sera from both case groups.Conclusions:We suggest that this band be extracted and its amino acids sequence determined to produce Synthetic Polypeptide for immunization studies.

Evaluation of the immune response in BALB/c mice induced by a novel DNA vaccine expressing GRA14 against Toxoplasma gondii

“…The protein concentration was determined using Bradford method. The TLA was filtered through a 0.22‐μm pore sterile filter and was kept at −80°C until use …”

“…To date, the production of vaccine against human toxoplasmosis was not successful and remains an unsolved problem. Till now, different types of vaccines of the parasite for immunization studies have been used including: the strain of the avirulent live parasites, killed parasites, radiation‐attenuated strains and parasite antigens …”

“…Till now, different types of vaccines of the parasite for immunization studies have been used including: the strain of the avirulent live parasites, 11 killed parasites, 12 radiation-attenuated strains 13 and parasite antigens. [14][15][16][17] In recent years, significant progress has been made in development of an effective and safe vaccine against T. gondii based on molecular vaccines. 10,18 Toxoplasma gondii has several antigens that play an important role in the microorganism pathogenesis and parasite evasion of the host immune responses.…”

IgG subclass responses to excreted-secreted antigens of Plasmodium falciparum in a low-transmission malaria area of the Peruvian Amazon

“…Excreted-secreted antigens are fundamental pieces in the host-parasite interaction and are utilized by various parasites to modulate the immune response of the host [ 24 – 26 ]. These antigens have been recognized for their use in serological diagnostics [ 27 – 29 ] and immunizations [ 30 , 31 ] in many different parasitic species. The excreted-secreted antigens of P. falciparum ( Pf -ESAs) have been shown to be involved in the process of erythrocyte invasion, the activation of antibodies and lymphocytes, and in complications of infection (reviewed in [ 24 ]).…”

Evaluation of Immunogenic Effect of Toxoplasma gondii RecombinantSAG-1 Antigen with Propranolol as Adjuvant in BALB/c Mice

“…The challenge test was performed with subcutaneous injection of 1000 alive and active RH strain tachyzoites to five mice from each group on the 20th day after the last immunization and the survival days of each group of mice were monitored until 3 weeks. 31,32…”