Milner A R, Marshall I D
J Virol. 1984 Apr;50(1):66-72. doi: 10.1128/JVI.50.1.66-72.1984.
The initial stages of infection of pregnant mice at gestation day 11 with either the T48 strain of Ross River virus or avirulent Semliki Forest virus are similar. With both infections, a hematogenous spread of virus to the placenta occurs. The viruses subsequently replicate to high titer in all placentas and are able to persist in the presence of specific maternal antiviral antibodies. There is a delay of at least 1 to 2 days between the initial detection of virus in the placenta and the onset of fetal infection. With Semliki Forest virus, abortion occurred in all mothers and appeared to be preceded by infection of all fetuses. However, when Semliki Forest virus was given at other stages of pregnancy, abortion was less common, and in all non-aborted pregnancies at least one uninfected fetus was observed. This situation was similar to that with Ross River virus, in which abortion was not observed and fetal infection and death were only seen in a proportion of fetuses. Within each pregnancy, the outcome of the two in utero infections appeared to result from similar mechanisms, with the fate of an individual fetus depending upon the timing of the passive transfer of anti-viral immunoglobulin G from the mother relative to the timing of fetal infection by virus from the placenta. Although the passive maternal immunoglobulin G protected susceptible fetuses against infection, antibody did not mediate in utero recovery of infected fetuses or clear placental infection.
在妊娠第11天，用罗斯河病毒T48株或无毒力的塞姆利基森林病毒感染怀孕小鼠，其感染的初始阶段相似。在这两种感染中，病毒都通过血液传播至胎盘。随后，病毒在所有胎盘中大量复制，并能在母体特异性抗病毒抗体存在的情况下持续存在。从在胎盘中首次检测到病毒到胎儿感染开始，至少有1至2天的延迟。对于塞姆利基森林病毒，所有母鼠均发生流产，且似乎在所有胎儿感染之前就已出现。然而，当在妊娠的其他阶段给予塞姆利基森林病毒时，流产较少见，并且在所有未流产的妊娠中，至少观察到一个未感染的胎儿。这种情况与罗斯河病毒相似，在罗斯河病毒感染中未观察到流产，仅在一部分胎儿中出现胎儿感染和死亡。在每次妊娠中，两种子宫内感染的结果似乎是由相似的机制导致的，单个胎儿的命运取决于母体抗病毒免疫球蛋白G被动转移的时间相对于胎儿被胎盘病毒感染的时间。尽管母体被动免疫球蛋白G可保护易感胎儿免受感染，但抗体并不能介导感染胎儿在子宫内的恢复或清除胎盘感染。
