final program.qxd - Parallels Plesk Panel

FP 1.3
An in vitro System for HIV-1 Selective Transmission using Human Genital
Epithelial cells
Z.W. Wu 1 , G.F. Fu 1 , Y.Y. Hou 1 , and Z.W. Chen 2
1
Center for Public Health Research, Nanjing University, Nanjing, China;
2
Aaron Diamond AIDS Research Center, New York, USA
Objectives
An in vitro culture system, using human genital epithelial cell lines, was established for
investigating HIV-1 sexual transmission. The system was used to study the efficiency of
CCR5 and CXCR4 virus transfer from the epithelial cells to CD4+ cells and the
mechanisms of selective transmission during sexual transmission of HIV-1.
Methods
Ect1, End1 and VK2 are HPV E6/E7 gene-transformed human ectocervical, endocervical
and vaginal epithelial cell lines, respectively. These cells formed monolayers in culture,
with morphology similar to their corresponding tissues. The culture monolayers were
pulsed with CCR5 or CXCR4 using HIV-1 and washed off unbound viruses. H9 cells or
IL-2-stimulated human PBMCs were co-cultured with the monolayers for 18 hours,
recovered and then re-cultured for a period of 6-9 days. Virus production was monitored
sequentially and the relative transmission efficiency of CCR5 and CXCR4 viruses was
investigated.
Results
All three epithelial cell lines were refractory to HIV-1 infection due to the lack of CD4
expression. However, virus can efficiently adsorbed to the epithelial monolayers via heparin
sulfate moiety of proteoglycans and remained infectious for up to 9 days in culture. The
adsorption and releasing of CCR5 and CXCR4 viruses were not significantly different.
Upon co-culture with IL2-stimulated human PBMCs, CCR5 virus was efficiently
transmitted and replicated in the PBMCs. To the contrary, CXCR4 virus was poorly
transmitted and replicated though evidence showed that the virus was not defective since
it replicated well when a T cell line (H9) was used. Preliminary studies showed that the
differential replication of CCR5 and CXCR4 viruses in PBMCs did not account for the
differences of CCR5 and CXC4 viruses in co-cultured PBMCs, suggesting that CXCR4
virus was blocked during the transfer from the epithelial cells to the PBMCs.
Conclusions
1. The human genital epithelial cell-based in vitro culture system is a suitable tool for
investigating the mechanisms of HIV-1 sexual transmission;
2. CCR5 and CXCR4 viruses were differentially transmitted from the epithelial cells to
IL-2-stimulated human PBMCs with CXCR4 virus largely blocked during the co-culture;
3. The epithelial-PBMCs interface may play important roles in selecting virus transmission
and this co-culture system may serve to delineate the molecular mechanisms of viral
sexual transmission.
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