SIMIAN IMMUNODEFICIENCY VIRUS-INFECTION OF MACAQUE PRIMARY PLACENTAL CELLS

We have characterized the ability of a simian immunodeficiency virus. SIVmne strain E11S, to infect macaque placental trophoblast and Hofbauer cells. These primary placental cells were permissive to SIVmne infection, regardless of gestational age. Virus production by the infected cells was determined as time-dependent viral core antigen p27 production, followed by verification of the proviral gag/LTR DNA sequences in the infected cells using a polymerase chain reaction assay. Of more than six placentas tested, SIVmne infection of placental cells at an early gestational age (i.e., days 55 or 78) produced more than 10-fold the amount of virus core antigen p27 than did placental cells infected at a late gestational age (i.e., days 135 or 165). In addition, SIVmne infection of trophoblast cells was inhibited by SIVmne neutralizing macaque serum but not by normal serum, indicating the specificity of virus infection. Furthermore, the amount of SIV core antigen p27 produced by the virus-infected trophoblast and Hofbauer cells was shown to be dependent on the multiplicity of virus infection, Collectively, our results indicate that macaque trophoblast and Hofbauer cells can be infected by SIV and that both gestational age and viral dose may play a role in the extent of viral infection.