革螨、恙螨感染汉坦病毒最小感染阈值及增长的动态观察

目的　研究螨 (革螨、恙螨 )感染汉坦病毒 (HantavirusHV)阈值和潜伏期。方法　采用革螨、恙螨叮刺不同感染剂量HV的乳鼠 ;用组织培养半数感染剂量 (5 0 %tissuecultureinfectivedose,TCID50 )测定、计算螨最小感染HV阈值 ;并动态观察HV在螨体内增殖 ,计算HV在螨体内的潜伏期。结果　在测定的 8组中革螨除 1 5LD5 0未感染外 ,其余 7组均能使革螨感染 ,HV在革螨体内开始增殖时间约在叮刺后第 2 5～ 30d。恙螨在测定的 8组中除 1 5和 5LD5 0未感染外 ,其余 6组均能使革螨感染 ,HV在恙螨增殖时间约在叮刺后第 30～ 4 0d。原位分子杂交检测发现HV阳性信号多见于螨的中肠细胞内 ,卵巢、卵细胞较少。结论　革螨感染HV的最小阈值为 5TCID50 ,HV在革螨体内潜伏期约 2 5～ 30d。恙螨感染HV最小阈值为10TCID50 ,HV在恙螨体内潜伏期为 30～ 4 0d。

Dynamic observation on the minimal threshold of infection and the initiation of virus growth in rats bitten by infected chigger and gamasid mites

To study the infection threshold and the incubation period of virus growth in rats bitten by infected chigger and gamasid mites,the suckling rats were inoculated with different doses of Hantaan virus (HV) by biting with infected mites,and the minimal threshold of infection was calculated by using the 50% tissue culture infective dose (TCID 50).In addition,a dynamic observation was made to search for the time of growth of virus in mites,there by to determine the incubation period of virus infection.It was found that,in the 8 groups of the gamasid mites,7 groups could induce infections except that infected with 1.5 LD 50 dosage of virus,and the time growth of viruses started on 15-20 days after biting with mites.Out of 8 groups of the chigger mites,6 groups were infected with HV except those infected with 1.5 and 5 LD 50 dosages of virus,and the time of growth of viruses started on 30-40 days after biting with mites.By molecular hybridization in situ,the positive signals of HV were more frequently observed in midgut cells than those observed in ovary and eggs of mites.It concludes that the minimal thresholds of HV infection in gamasid mites and in chigger mites were 5 and 10 TCID 50 respectively,and the incubation periods of infection in these two kinds of mites are 25-30 days and 30-40 days respectively.