Endris R G, Hess W R
Plum Island Animal Disease Center, USDA-ARS-NAA, Greenport, NY 11944-0848.
J Med Entomol. 1994 May;31(3):373-81. doi: 10.1093/jmedent/31.3.373.
Transovarial transmission experiments were conducted with three groups of Ornithodoros (Pavlovskyella) marocanus Velu; one group consisted of 27 pairs of adults that had been fed as larvae on a pig with a viremia of 10(7.4) HAd50/ml of African swine fever virus (ASFV). The second and third groups each consisted of 100 pairs of adults fed on a viremic pig (10(4.5) HAd50/ml) as adults. The first group underwent five gonotrophic cycles over a 554-d period. The second and third groups underwent three and two gonotrophic cycles, respectively. All larvae were fed in individual cohorts on naive pigs and the resulting nymphs were assayed by cohort for ASFV. None of the larvae transmitted ASFV to naive pigs by bite and ASFV was not isolated in swine buffy coat cultures from any cohort of nymphs. Therefore, O. marocanus does not exhibit transovarial transmission of ASFV. Venereal transmission experiments were conducted with pairs of O. marocanus in which either the female (100 pairs) or the male (100 pairs), respectively, had fed on a viremic pig (10(4.5) HAd50/ml). Both groups underwent at least two gonotrophic cycles over a 470-d period, were sampled periodically for the presence of ASFV, and the progeny were tested for the presence of ASFV. Venereal transmission from male to female occurred in 10% (1/10) of O. marocanus after the first gonotrophic cycle, but not after the second or third gonotrophic cycle, and transovarian transmission in these groups was not observed. Venereal transmission from infected females to uninfected males did not occur. ASFV persisted through five gonotrophic cycles over a 554-d period in 30% of adults fed on a viremic pig as larvae. ASFV was cleared during three gonotrophic cycles within a year from nearly all ticks fed on a viremic pig as adults. Virus-induced mortality rats of 12-80% occurred among ticks fed on viremic animals, whereas, no mortality was seen in ticks fed on uninfected animals. ASFV infection in ticks did not effect feeding frequency, egg-hatch rate, or the oviposition rate among females fed on a viremic pig as adults. The oviposition rate for females fed on a viremic pig as larvae was reduced by 63.4%. Parthenogenesis was not observed among O. marocanus. The mean gonotrophic cycle duration for pig-fed O. marocanus at 27 degree C was 19.8 d and the mean fecundity was 88.3 +/- 17.9 eggs/female/gonotrophic cycle.
对三组摩洛哥钝缘蜱（Pavlovskyella属）进行了经卵传播实验；一组由27对成虫组成，这些成虫在幼虫期以每毫升含10(7.4) 半数血凝吸附剂量50（HAd50）非洲猪瘟病毒（ASFV）的病毒血症猪为食。第二组和第三组各由100对成虫组成，它们在成虫期以病毒血症猪（每毫升含10(4.5) HAd50）为食。第一组在554天的时间里经历了5个生殖营养周期。第二组和第三组分别经历了3个和2个生殖营养周期。所有幼虫在单独的群体中以未感染的猪为食，所产生的若虫按群体进行ASFV检测。没有幼虫通过叮咬将ASFV传播给未感染的猪，并且在任何若虫群体的猪血沉棕黄层培养物中都未分离到ASFV。因此，摩洛哥钝缘蜱不表现出ASFV的经卵传播。对摩洛哥钝缘蜱进行了性传播实验，其中分别有100对雌蜱或100对雄蜱以病毒血症猪（每毫升含10(4.5) HAd50）为食。两组在470天的时间里至少经历了2个生殖营养周期，定期取样检测ASFV的存在情况，并对后代进行ASFV检测。在第一个生殖营养周期后，10%（1/10）的摩洛哥钝缘蜱发生了从雄蜱到雌蜱的性传播，但在第二个或第三个生殖营养周期后未发生，并且在这些群体中未观察到经卵巢传播。未发生从感染雌蜱到未感染雄蜱的性传播。在幼虫期以病毒血症猪为食的成虫中，30%的成虫在554天的时间里ASFV持续存在5个生殖营养周期。在一年内，几乎所有在成虫期以病毒血症猪为食的蜱在3个生殖营养周期内清除了ASFV。以病毒血症动物为食的蜱中，病毒诱导的死亡率为12% - 80%，而以未感染动物为食的蜱未观察到死亡。蜱感染ASFV对成虫期以病毒血症猪为食的雌蜱的取食频率、卵孵化率或产卵率没有影响。幼虫期以病毒血症猪为食的雌蜱的产卵率降低了63.4%。在摩洛哥钝缘蜱中未观察到孤雌生殖。在27摄氏度下，以猪为食的摩洛哥钝缘蜱的平均生殖营养周期持续时间为19.8天，平均繁殖力为每雌蜱/生殖营养周期88.3 +/- 17.9枚卵。
