Multi-epitope chimeric antigen used as a serological marker to estimate Plasmodium falciparum transmission intensity in the border area of China-Myanmar.
BACKGROUND
Following the decline of malaria transmission in many countries and regions, serological parameters have become particularly useful for estimating malaria transmission in low-intensity areas. This study evaluated a novel serological marker, Malaria Random Constructed Antigen-1 (M.RCAg-1), which contains 11 epitopes from eight Plasmodium falciparum antigens, as a tool for assessing malaria transmission intensity along the border area of China-Myanmar.


METHODS
Serum from Plasmodium falciparum and P. vivax patients was used to detect the properties of M.RCAg-1 and antibody responses. Cross-sectional surveys were conducted at the China-Myanmar border and in Hainan province in 2012 and 2013 using cluster sampling. Filter blood spot papers were collected from all participants. Antibodies against M.RCAg-1 were detected using indirect ELISA. The Mann-Whitney test and Spearman's rank correlation test were performed to analyze antibody data. P. falciparum malaria transmission intensity was estimated using a catalytic conversion model based on the maximum likelihood of generating a community seroconversion rate (SCR).


RESULTS
M.RCAg-1 was well-recognized by the naturally acquired anti-malaria antibodies in P. falciparum patients and had very limited cross-reactivity with P. vivax infection. The total amount of IgG antibodies was decreased with the decrease in parasitemia after taking medication and lasted several weeks. In a population survey, the antibody levels were higher in residents living close to the China-Myanmar border than those living in non-epidemic areas (P < 0.0001), but no significant difference was observed between residents from Hainan and non-epidemic areas. The calculated SCR was 0.0128 for Jieyangka, 0.004 for Susuzhai, 0.0047 for Qiushan, and 0.043 for Kayahe. The estimated exposure rate obtained from the anti-M.RCAg-1 antibody level correlated with traditional measures of transmission intensity derived from altitude.


CONCLUSIONS
Our study demonstrates that M.RCAg-1 is potentially useful as a serological indicator of exposure to P. falciparum malaria, especially for malaria surveillance in low transmission areas.
Department of Microbiology and Parasitology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China.
Mei-Xue
MX
Yao
Yunnan Institute of Parasitic Diseases, Puer, Yunnan, China.
Xiao-Dong
XD
Sun
Department of Microbiology and Parasitology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China.
Yu-Hui
YH
Gao
Department of Biochemistry and Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, China.
Zhi-Bin
ZB
Cheng
Department of Microbiology and Parasitology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China.
Wei-Wei
WW
Deng
Department of Microbiology and Parasitology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China.
Jia-Jia
JJ
Zhang
Department of Microbiology and Parasitology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and School of Basic Medicine, Peking Union Medical College, Beijing, 100005, China. wangh@ibms.cams.cn.
Heng
H
Wang
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D000939:Epitopes / Q000276:immunology*; D005260:Female; D006801:Humans; D016778:Malaria, Falciparum / Q000453:epidemiology* / Q000469:parasitology / Q000635:transmission; D008297:Male; D008875:Middle Aged; D002052:Myanmar / Q000453:epidemiology; D010963:Plasmodium falciparum / Q000276:immunology*; D016036:Seroepidemiologic Studies; D055815:Young Adult
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D000939:Epitopes
China-Myanmar border; Multi-epitope chimeric antigens; Plasmodium falciparum; Serology; Transmission intensity