[Preliminary Analysis of the Genetic Loci of SAG1 and SAG3, the Surface Antigens of Toxoplasma gondii, in HIV-positive People in Dali of Yunnan Province].

OBJECTIVE: To identify the genotypes of Toxoplasma gondii that infects HIV-positive people in Dali of Yunnan Province through analyzing the genetic loci of the surface antigens SAG1 and SAG3. METHODS: A total of 291 blood samples from HIV-positive cases were collected from the HIV/AIDS Prevention and Control Institution in Yunnan. Nested PCR was used to amplify SAGI and SAG3 genes in the blood samples. The products were digested with restriction enzymes Sau96 I, Hae II and Nci I, and sequenced. RESULTS: Of the 291 HIV-positive blood samples, 64 showed successful amplification of SAGI gene, and 42 of SAG3 gene, with product sizes of 390 bp and 225 bp, respectively. Enzymetic digestion of the PCR products resulted in fragments of 350 bp and 50 bp for SAGI, and -200 bp band for SAG3, consistent with RH, a particular type I strain of T. gondii. Sequencing of the SAG1 and SAG3 PCR products showed that their sequence identities with SAGI (Accession No. GQ253073) and SAG3 (Accession No. JX218225.1) of the type I strain of T. gondii were 99.98%-100% and 99.96% -99.98% respectively. CONCLUSION: The Toxoplasma gondii in HIV-positive cases in Dali of Yunnan Province is the type I strain of T. gondii.

[Analysis of sites of Toxoplasma gondii SAG2 gene in blood of HIV-positive people in Lincang City, Yunnan Province].

OBJECTIVE: To preliminarily understand the genotype characteristics of Toxoplasma gondii in blood of HIV-positive persons in Lincang City, Yunnan Province. METHOD: Two segments of SAG2 gene of T. gondii from blood samples of HIV-positive persons in Lincang City were extracted and amplified by using the nested PCR method and the genotype was identified and compared with the standard strain (Type I) of Toxoplasma gondii. RESULTS: Thirty-five SAG2 genes (241 bp) and 35 SAG2 genes (221 bp) of T. gondii were amplified from 170 blood samples of the HIV-positive people, and 4 of each case were selected and digested with enzyme, then 2 aim gene fragments of each case were chosen and compared with the standard strain (Type I) of T. gondii. The digestion of SAG2 gene (241 bp) showed the genotype of the blood samples was Type I or Type II, and the digestion of SAG2 gene (221 bp) confirmed that the genotype was Type I. CONCLUSION: It is preliminarily confirmed that the genotype of T. gondii in blood of HIV-positive persons in Lincang City, Yunnan Province is Type I.

[Comparation of Toxoplasma gondii separated from HIV-positive people and RH strain GRA6 gene].

OBJECTIVE: To comparatively analyze Toxoplasma gondii separated from HIV-positive people and RH strain GRA6 gene. METHODS: By using the nested PCR, the amplification of Dali HIV-positive blood samples and RH strains of Toxoplasma GRA6 genome was performed. The GRA6 gene amplification positive product was selected and the electrophoresis imaging was performed by being digested with the Mse I endonuclease, and the gene sequences were measured and analyzed. RESULTS: The GRA6 gene fragment (800 bp) was successfully amplified, and about 600 bp and 200 bp bands were got by Mse I. The sequencing results showed that T. gondii GRA6 gene positive samples had 2 nucleotide variation compared with T. gondii strain RH, namely 447 base pair at C becoming G, and 623 base pair at G becoming T. At 146 bp and 690 bp, the Mse I restriction sites (TTAA) were found. CONCLUSION: The preliminary judgment shows that the Dali HIV-positive T. gondii genotype is consistent with RH strain, belonging to genotype I.

[Study and application of surface antigen in tachyzoites of Toxoplasma gondii].

Toxoplasma gondii is an intracellular protozoan parasite that infects all warm-blooded animals. The surface antigens of T. gondii with the potential for application as antigens of diagnosis and vaccines have been studied extensively in recent years, especially for P43, P35, P30, P23 and P22. The studies on the surface antigen in tachyzoites of T. gondii are reviewed in this paper.

[Advances in genetyping of Toxoplasma gondii].

Toxoplasma gondii is a nucleated cell obligate parasite, and can cause severe toxoplasmosis. The genetypes of Toxoplasma gondii isolates of different host infections have significant differences, and the pathogenicity and sensitivity to drugs of different genotypes of Toxoplasma gondii isolates are also significantly different. At present, the analysis of Toxoplasma gondii genotypes is performed by using PCR-RFLP, PCR of highly repetitive sequences, multiple PCR and nested PCR techniques, and the multiple loci of amplification are usually B1, SAG2, HSP70, GRA6 and other genetic markers. There are main 3 traditional genotypes of Toxoplasma gondii, and along with the deepening and extension of research, more and more genotypes are found. This paper reviews the advances in the research of Toxoplasma gondii genotypes.

[Genotypes of Toxoplasma gondii isolates from HIV positive patients in Yunnan Province].

One hundred and fifty serum samples of HIV positive patients were collected in western Yunnan Province from September 2011 to December 2012. Toxoplasma gondii B1 gene was amplified by nested PCR. Genotyping of T. gondii isolates were performed by restriction fragment length polymorphism (RFLP) with Pm1 I and Xho I. 13 samples were found positive with the B1 gene (530 bp) amplification and belonged to type I. The sequencing results showed that 4 T. gondii B1 gene positive samples were identical, with 3 nucleotide variation compared with T. gondii strain RH (type I) B1 gene (GenBank No. AF179871), and in the other sample a "G --> A" mutation at 230bp was detected. The results indicated that the genotype of Toxoplasma gondii in HIV positive patients in Yunnan Province is type I.

[PCR-derived technology in gene identification and typing of Toxoplasma gondii].

Different genotypes of Toxoplasma gondii show a great diversity in pathogenicity and drug sensitivity. Application of the PCR-derived technologies in gene identification and typing of T. gondii provides an important basis to clinical diagnosis and treatment. This article reviews the relevant technologies in gene identification and typing of T. gondii.

[Serological investigation of Toxoplasma gondii infection in HIV positive cases in Dali and Dehong of Yunnan].

Serum samples were collected from HIV positive cases (927) and HIV, negative ones (80) from June 2010 to August 2011 in Dali and Dehong Prefectures of Yunnan. Serum anti-Toxoplasma gondii IgG was detected by ELISA. The overall anti-Toxoplasma gondii IgG positive rate among HIV positive cases and HIV negative ones was 35.1% (325/927) and 23.8% (19/80), respectively. In HIV positive cases, the seropositive rate was 30.3% (178/588) in Dali and 43.4% (147/339) in Dehong. The seropositive rate was significantly different among ethnic groups (chi2 = 28.433, P < 0.05). No significant difference was found among age groups (chi2 = 4.248, P > 0.05), and the age group of 41-60 showed the highest positive rate (36.1%, 103/285). The seropositive rate was 35.6% (203/571) in males and 34.3% (122/356) in females (chi2 = 0.158, P > 0.05).

[Molecular diagnosis of toxoplasmosis].

This paper reviews the domestic and foreign literatures regarding molecular diagnosis of toxoplasmosis. The nucleic acid molecule hybridization and Toxoplasma gondii gene sequences for polymerase chain reaction (PCR), common and conventional PCR, nested PCR, real-time quantitative PCR, immune PCR, in-situ PCR, loop-mediated isothermal amplification technology are introduced.

[IgG antibody level in saliva from rabbits infected with Trichinella spiralis].

Twenty-eight Japanese big ear rabbits were randomly divided into control group and experimental group. Twenty rabbits in experimental group were each infected with 3000 larvae of Trichinella spiralis. Serum and saliva samples were collected at pre-infection and every week after infection, and were examined for IgG antibody by indirect ELISA using T. spiralis muscle larvae excretory-secretory antigen (MLESA). At 1, 2, 3, 4, 5 and 6 weeks afer infection, the positive rate in saliva samples was 10%, 15%, 40%, 65%, 85%, and 95%, respectively; and that of serum samples was 35%, 50%, 80%, 90%, 100%, and 100%, respectively. The positive rate was significantly different between saliva and serum samples at 1, 2 and 3 weeks post-infection (chi2 = 3.58, 5.23, 6.67, P < 0.05), but no significant difference at 4, 5, and 6 weeks post-infection (chi = 0.12, 1.03, 1.03, P > 0.05). The results indicate that the indirect ELISA using MLESA to detect IgG antibody in saliva may be helpful for clinical diagnosis of trichinellosis.