AimTo evaluate the efficiency of gene amplification technique used in detecting the specimens colleted from rodents to identify natural epidemic foci of scrub typlus. MethodMice of Kunining strain were experimentally infected by a certain amount of Oriential tsutsugamushi. The specimens of blood clot and spleen from the infected animals were detected by nested polymerase chain reaction(nPCR)specific to O. T sutsugamush at the day 3,6 and 9 of post-infection. Then the technique was used for detection of samples collected from field. As an infected index ,the specimen was considered to be positive only if a 88-bp DNA fragment from Sta 58kDa gene of O. Tsutsugamushi could be produced. According to the study ,it was estimated whether or not that the sampling area is a natural epidemic focus of the disease. ResultsThe specimens of both blood clot and spleen from the mica at day 3 of post-infecction showed negative to the specific PCR product ,but positive when detected at day 6 and hereafter. Of 111 spleen samples from the field collections in the northwest of Fujian province,one was positive, and another positive sample was in the 29 blood clots from Jiangxi province. It is demonstrated that these areas have been the natural epidemic foci. Conclusion The nPCR method is of highly sensitive and specific to be used in the etiologic study on specimens from field rats.

AimTo investigate cell mediated-immunity induced by porin of Salmonella typhimurium(STM). Methods Level of delayed-type hypersensitivity(DTH), IL-2 of immunized BALB/c mice were determined by footpad swelling,MTT and transfered protective rate of T cells purified by neloy wool were studied with 500LD50 of the bacteria(intraperitoneally). Results A marked level of DTH(3. 6±0. 2,P＜0. 01),IL-2(26.2±4.9,P＜0. 01) and the immuinized T cells transfer protec tive level (42.9％ ,P＜0. 01) was induced by porin from STM. Conclusion These results indicated that porin of STM might in duced stronger CMI in BALB/c mice.

AimIn order to investigate the function of hsp86 gene in Plasmodium falciparum,two fragments of heat shock protein 86 gene of Plasmodium falciparum were amplified and the targeting vectors were constructed. MethodsCulturing the Plasmodium falciparum in vitro,extracting the genome DNA, amplifing the targeted gene with PCR ,contructing the target vector and identifing with restricted enzymes and sequencing. ResultsThe relative fragments were amplified successfully. The insertion and replcement vector with hsp86 gene were constructed. ConclusionConstructing successfully the replacement and insertion vector which is used to the gene knockout in Plasmodium falciparum.

Malaria vaccines are being developed against different stages in the parasite's life cycle. Although not directly protective ,the sexual stage vaccines would induce antibodies that would prevent infection of mosquitoes when ingestedin a bloodmeal containing sexual stage parasites. pfs25 has been tested to be an important candidate antigen for malarial transmission blocking vaccine . In this report we analyzed the complete code of pfs25 gene of Plasmodium falciparum PFD-3/YN isolate. The result shows that the gene encoding pfs25 of PED-3/YN isolate has a mutant which generates a PstI endonuclease restriction site and shares 99.2％ nucleotide homology with that of NF4 isolate.

To insight into genetic differences between chloroquine-resistant line (RC) and chloroquine-sensitive strain (N) of Plasmodium berghei. MethodsAfter continous cbloroquine-pressure upon RC line at higher dosage (50mg/kg. d) ,total RNAs from the RC line and the N strain of P. berghei were isolated for simplified differential display reverse transcript polymerase chain reaction (sDDRT-PCR ). The generated differential fragments had been repetitively rescued and identified by PCRs before one pair of suspected differential fragments (N25 and R25 )were cloned and sequenced. Then, their sequences were analyzed through PC-gene program and BLAST search. ResultsThough the identity of two nucleotide sequences of N252 and R251 ,cloned separately from the N25 and R25 fragments, were up to 99.8％ ,their predicted amino acid secondary structures were quite different due to multiple mutations. Compared with the published sequences in GeneBank,EMBL,DDBJ and PDB database ,no similar gene was found ,using BLAST search. However their partial nucleotide sequences (62nt from query 128nt to189nt bore highly homology to part sequence(from 1053nt to1114nt)of rattus norvegicus mRNA for phospholipase B,up to 93.5％ in N251 and 91.9％ in N252 respectively. ConclusionIt is feasible to isolate chloroquine-resistant related genes by using simplified DDRT-PCR combined repetitively rescuing and PCR identifying the interest differential DNAs together with sequence analyses.

This study was undertaken to investigate mother-to-infant transmission of human parvovirus B19 and the significance of prevalence of B19 virus in abnormal fetuses in Guandong. The polymerase chain reaction (PCR)was established to detect parvovirus B19 DNA in 700 sera from 350 maternal-infant pair groups. The prevalence of B19 virus DNA was 1.14％ (4/350)and 0.28％(1/350)in the sera of pregnant women and cord blood of their neonates respectively. Parvovirus B19 DNA sequences were also detected in abnormal fetuses and new-born by PCR. The positive results were obtained in 5 samples of fetal tissues from 17 abnormal fetuses and in 3 those of neonatal tissues from 7 cases of neonatal death. The amplified products of PCR were identified to be the target DNA with Hae Ⅲ digestion. By in situ hybridization ,parvovirus DNA could be detected mainly in the nuclei of immature hematopoetic cells within fetal brain or spleen whose PCR tests were positive. The study results suggest that human parvovirus B19 infection does exist in maternal-infant transmission in Guangdong and might lead to harm on fetuses,but the prevalence rate of B19 virus may be very low. The evaluation of B19 virus infection might depend on reliable assay to determine present infection or past infection.

AimTo study the mechanism of ABZ,ABZSX and ABZSN on Ascaris Suum. MethodsThe activities of enzyme complexes in mitochondria were detected by spectrophotometer for the study of effects of ABZ, ABZSX and ABZSN on the anaerobic respiratory chain of enzyme complexes in mitochondria of Ascaris Suum muscle and rat liver. ResultsThe activity of succinate CoQ reductase in Ascaris muscle mitochondria was apparently suppressed by ABZ ,ABZSX. Conclusion Preliminary study on the mechanism and toxicity of ABZ through enzyme studies,in order to find a more effective and satisfactory drug with low toxicity for clinical use.

The sera of 206 cases with hydatid disease diagnosed by B-ultrasound and X-ray in survey scene had been examined by Dot-ELISA and IHA with Qinghai cystic hydatid antigen, ELISA With Xingjiang cystic hydatid antigen and Em18-EliB with alveolar hydatid antigen. The results showed that the sero-positive rates were 90. 37％ and 91.98％ in these cases with cystic hydatid disease by Dot EliSA and IHA with Qinghai cystic hydatid antigen respectively. The sero-positive rate was 75. 94％ in same cases by ELISA with Xingjiang cystic hydatid antigen. The sero-positive rateswere 77.27％ 81. 82％ and 65. 91 ％ in those cases with the whole calcific cystic hydatid disease by above three methods respectively, and the sero-positive rates were lower in whole calcific cystic hydatid than that in other cystic hydatid disease. The sero-negative cases belonged to cystic hydatid disease which located in lungs of livers alone. The results by EM18-ELIB with alveolar hydatid antigen showed that the sero-positive rates were 73. 68％ and 5. 88％ in those cases with alveolar hydatid disease and with cystic hydatid disease diagnosed by B-ultrasound and X-ray respectively,and the sero-positive rate was 15.91 ％ in whole calcific cystic hydatid disease. The ratio of the number of positive seras to that of negative seras was 1 to 7 approximately. The value and mean of different serological methods in diagnosis and judge diagnosis for cystic and alveolar hydatid disease had been discussed.

The Many experiments show that pH affect the growth of romastigotes of L donovani. But the control tests with Acid - base scale have not been reported on the growth of promastigotes from different genesis. This paper reports that pH has different nfluence on several kinds of promastigotes from different genesis. We obseved that the growth of promastigotes of L. doncvani is inhibited when pH is 4.6 and 8.6.

AimTo study the effect of interferon gamma( IFN-γ) and tumor necrosis factor alpha(TNF-α) in the immune pathogenesis of dengue virus infection. Method The serum levels of IFN-γ and TNF-α were measured with emzyme linked immunosorbent assay (ELISA) method in 30 cases of the patients with the dengue virus infection in Guangzhou district. The results were treated with t-test of two sample mean. ResultsThe serum levels of IFN-γ and TNF-α in patients with the dengue virus infection were much higher than healthy controls( P ＜ 0.05、 P ＜ 0.01 ). IFN-γ was detectable on the first day of postinfection. Level of IFN-γ reached their peaks on the second day, then declined . The level of TNF-α had an obvious rise from the second day and reached their peaks on the third day, then declined. ConclusionThe data suggest that the IFN-γ and TNF-α may play an important role in the dengue virus pathogenicity and immunity.