ABSTRACT
Congenital infection with human cytomegalovirus (CMV) through the placenta is one of the major causes of birth and developmental abnormalities. Guinea pig CMV (GPCMV) causes in utero infection, which makes its animal models useful for studies on congenital diseases. Here, we established an ex vivo culture method for tissue slices prepared from guinea pig placentas and demonstrated that viral spread in the model resembles those in the placenta of GPCMV-infected animals and that the infection is independent of the pentameric glycoprotein complex for endothelial/epithelial cell tropism. Thus, this model affords a useful tool for pathobiological studies on CMV placental infection.
Subject(s)
Cell Culture Techniques/methods , Cytomegalovirus Infections/congenital , Cytomegalovirus Infections/pathology , Placenta/pathology , Pregnancy Complications, Infectious/pathology , Animals , Disease Models, Animal , Female , Guinea Pigs , Infectious Disease Transmission, Vertical , Models, Theoretical , Organ Culture Techniques , Placenta/virology , Pregnancy , Primary Cell Culture/methodsABSTRACT
The GP129, GP131 and GP133 genes of guinea pig cytomegalovirus (GPCMV) are homologues of human cytomegalovirus UL128, UL130 and UL131A, respectively, which are essential for infection of endothelial and epithelial cells, and for viral transmission to leukocytes. Our previous study demonstrated that a GPCMV strain lacking the 1.6 kb locus that contains the GP129, GP131 and GP133 genes had a growth defect in animals. Here, we demonstrated that the WT strain, but not the 1.6 kb-deleted strain, formed capsids in macrophages prepared from the peritoneal fluid. To understand the mechanism, we prepared GPCMV strains defective in each of GP129, GP131 and GP133, and found that they were all essential for the infection of peritoneal, splenic and PBMC-derived macrophages/monocytes, and for expression of immediate-early antigens in the macrophages/monocytes, although they were dispensable for infection of fibroblasts. Monocyte/macrophage tropism could be one of the important determinants for viral dissemination in vivo.
Subject(s)
Cytomegalovirus/pathogenicity , Macrophages, Peritoneal/virology , Monocytes/virology , Roseolovirus/pathogenicity , Viral Proteins/physiology , Animals , Cytomegalovirus/genetics , Cytomegalovirus/physiology , Gene Deletion , Genes, Immediate-Early , Genes, Viral , Guinea Pigs , Humans , Membrane Glycoproteins/genetics , Membrane Glycoproteins/physiology , Roseolovirus/genetics , Roseolovirus/physiology , Species Specificity , Viral Envelope Proteins/genetics , Viral Envelope Proteins/physiology , Viral Proteins/genetics , Virulence/genetics , Virulence/physiologyABSTRACT
BACKGROUND: Cytomegalovirus (CMV) is the most common cause of congenital virus infection. Infection of guinea pigs with guinea pig CMV (GPCMV) can provide a useful model for the analysis of its pathogenesis as well as for the evaluation of vaccines. Although glycoprotein B (gB) vaccines have been reported to reduce the incidence and mortality of congenital infection in human clinical trials and guinea pig animal models, the mechanisms of protection remain unclear. METHODS: To understand the gB vaccine protection mechanisms, we analyzed the spread of challenged viruses in the placentas and fetuses of guinea pig dams immunized with recombinant adenoviruses expressing GPCMV gB and ß-galactosidase, rAd-gB and rAd-LacZ, respectively. RESULTS: Mean body weight of the fetuses in the dams immunized with rAd-LacZ followed by GPCMV challenge 3 weeks after immunization was 78% of that observed for dams immunized with rAd-gB. Under conditions in which congenital infection occurred in 75% of fetuses in rAd-LacZ-immunized dams, only 13% of fetuses in rAd-gB-immunized dams were congenitally infected. The placentas were infected less frequently in the gB-immunized animals. In the placentas of the rAd-LacZ- and rAd-gB-immunized animals, CMV early antigens were detected mainly in the spongiotrophoblast layer. Focal localization of viral antigens in the spongiotrophoblast layer suggests cell-to-cell viral spread in the placenta. In spite of a similar level of antibodies against gB and avidity indices among fetuses in each gB-immunized dam, congenital infection was sometimes observed in a littermate fetus. In such infected fetuses, CMV spread to most organs. CONCLUSIONS: Our results suggest that antibodies against gB protected against infection mainly at the interface of the placenta rather than from the placenta to the fetus. The development of strategies to block cell-to-cell viral spread in the placenta is, therefore, required for effective protection against congenital CMV infection.
Subject(s)
Cytomegalovirus Infections/prevention & control , Placenta/virology , Roseolovirus/pathogenicity , Viral Envelope Proteins/immunology , Viral Vaccines/immunology , Adenoviridae , Animals , Antibodies, Viral/blood , Cytomegalovirus Infections/congenital , Cytomegalovirus Infections/immunology , DNA, Viral/isolation & purification , Female , Fetus/immunology , Guinea Pigs , Placenta/immunology , Pregnancy , beta-Galactosidase/immunologyABSTRACT
Development of alternative compounds for treatment of diseases caused by herpesviruses has been required, because (1) all approved anti-herpesvirus drugs target the viral DNA synthesis, (2) strains resistant against these drugs emerge after a long treatment, and (3) some drugs have inevitable side effects. There are three main approaches for the development of novel anti-herpesvirus drugs: (1) modification of the existing drugs to increase their stability and bioavailablity in vivo, (2) increase of the efficacy of the existing drugs by administrating with an additional drug, eg. which is for induction of lytic infections of gamma herpesviruses, and (3) identification of novel drug targets and their clinical development. This review updates the recent efforts for those approaches.
