[Proliferation and location of Hantaan virus in gamasid mites and chigger mites, a molecular biological study].
OBJECTIVE
To study the proliferation and location of Hantaan virus (HV) in gamasid mites and chigger mites and the significance of gamasid mites and chigger mites as vectors of transmission of hemorrhagic fever with renal syndrome (HFRS).


METHODS
Gamasid mites collected from the nests of wild rodents and chigger mites collected from the bodies of wild rodents and thick growth of grass in the field were raised. Two oligonucleotide primers were developed based on the gene fragments of cDNA of HV 76 - 118 strain to be used in RT-PCR. RNA was extracted from the suspension of the gamasid mites from the nests where rodents no HV had been found in whose lungs lived and from the unfed larvae of chigger mites, being formed groups of 5, 10, 30, or 50 individuals. RT-PCR was conducted to detect the HV-RNA in such suspension. The larvae, nymphs, and imagines of both kinds of mites were ground to make suspension at an interval of 20 days. Vero-E(6) cells were inoculated to measure the titer of 50% tissue culture infective dose (TCID(50))/ml of HV. Frozen sections of larvae, nymphs, and imagines of both kinds of mites were made. RT-PCR and in situ hybridization were conducted to detect the distribution of HV-positive particles. Monoclonal antigen technique was used to compare the antigenicity of the HV-RNA from the rodents, mites, and patients from the same epidemic areas.


RESULTS
HV-RNA was detected in gamasid mites and chigger mites. Except in the larvae of chigger mites 60 days after collection, titers of HV were detected and increased gradually in mites at different stages of life cycle. HV-RNA positive particles were detected in the epithelial cells of midgut and ovary, with the signal denser and more numerous in nymphs than in larvae. The genotypes of HV from rodents, mites and patients in the same endemic areas were identical: HTN type virus.


CONCLUSIONS
HV can be transmitted transstadially and proliferated in mites, gamasid mites and chigger mites play the role of vectors of transmission for HFRS.
Zhang
Yun
Y
Institute of Military Medicine, Nanjing Command of Chinese People's Liberation Army, Nanjing 210002, China.
Zhu
Jin
J
Tao
Kaihua
K
Wu
Guanghua
G
Guo
Hengbin
H
Wang
Jingjun
J
Zhang
Jiajü
J
Xing
Aihua
A
D000818:Animals; D002522:Chlorocebus aethiops; D005260:Female; D005838:Genotype; D018063:Hantaan virus / Q000235:genetics* / Q000254:growth & development; D006801:Humans; D017403:In Situ Hybridization; D007814:Larva / Q000821:virology; D008297:Male; D008925:Mites / Q000821:virology*; D009758:Nymph / Q000821:virology; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014709:Vero Cells
D012367:RNA, Viral