ABSTRACT
Objective To study the effect of IL-12 on Th1/Th2 cytokine expression level and the role of IL-12 in the shi ft ing of Th1/Th2 immune response against blood-stage Plasmodium b e ighei infection in mice. Methods [WT5”BZ ]BALB/c mice were infected with 5?105 parasitized RBC and received doses of 0.03 or 0.15 ?g/d of IL-12 on the day of infection and daily for 6 days post -in fection. The levels of IFN-? and IL-4 in sera or supernatants of splenic lymp hocyte cultured in vitro were detected by the EL ISA method. Results Compared with spleen cells fro m untreated mice, spleen cells from 0.03 ?g dose of IL-12-treated mice produ ced significantly higher level of Th1-associated cytokine IFN -?, but lower level of Th2-associated cytokine IL-4 in response to PHA or sA g stimulation on day 7 post-infection, whereas spleen cells from 0.15 ?g dose I L-1 2-treated mice produced significantly lower levels of IFN-? and IL-4. The le vel of IFN-? was apparent in the sera of mice treated with 0.03 or 0.15 ?g/d I L-12 on day 3 post-infection and peaked on the day 5 post-infection, but level of I FN-? even was significantly lower in mice treated with 0.15 ?g/d IL-12 comp ara ble to that in control mice on day 7 post-infection. The level of IFN-? was n ot detected in the sera of control mice through 7 days post-infection. [WT5” H Z] Conclusion Appropriate dose of IL-12 regulates the deve lop ment of resistance to P.berghei via a CD 4+ T h1 response, which involves the cytokines IFN-?. [HT5”SS] However, higher doses of IL-12 dramatically inhibite immune pro t ective ability, which may be detrimental to resistance against P .berghei infection. [
ABSTRACT
Objective To develop a method for detecting the genotype of Plasmodium vivax merozoite surface protein 1 (PvMSP-1) alleles. Methods According to the sequence characteristic of PvMSP-1, nested polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to amplify the polymorphic region of ICB5-ICB6 which contains Q repeats and PvuII restriction site (Sal-1 type). The PCR product was digested by PvuII restriction endonuclease and the digested fragments were observed by 2% agarose gel electrophoresis. The allelic type was determined according to the banding pattern. Results Bands in size of 400 bp (Belem type ) and/or 470 bp (Sal-1 type ) appeared in all 98 P. vivax isolates, no band was found in negative control. After PvuII digestion, two Sal-1 type fragments (120 bp and 350 bp) were obtained from 45 samples of 470 bp. Single-band of 400 bp appeared in 3 of 40 samples with 400 bp as Belem type, two bands of 120 bp and 280 bp appeared from other 35 samples as recombination type III, and another 2 bands with 120 bp and 240 bp as Korean isolate. Conclusion The result showed that the nested PCR-RFLP may be applied in the detection and identification of the three PvMSP-1 allelic types in China.
ABSTRACT
Objective To develop methods of extracting DNA from malaria parasites on Giemsa-stained blood smears. Methods Improved Na2HPO4 method and Chelex-100 ion-exchange technique were used to extract DNA from Giemsa-stained or unstained blood smears. Nested PCR was employed for amplification and identification of allelotypes in the Plasmodium vivax merozoite surface protein-1(PvMSP-1). Results Target DNA bands appeared in all samples of unstained thick blood smears, while no DNA bands were visible in the fixed and stained thin smears. Both methods identified PvMSP-1 alleles from smears with parasitemia of ≥0.01%. Conclusion It is feasible to identify PvMSP-1 alleles from Giemsa-stained blood smear.