Patterned Entry and Egress by Epstein–Barr Virus in Polarized CR2-Positive Epithelial Cells

Abstract

In polarized epithelium direction of viral entry and release correlates with proclivity of a virus to establish local versus systemic infection. The Epstein-Barr virus (EBV), whose principal tissue reservoir is B lymphocytes, also has disease manifestations in epithelium, suggesting intertissue spread potentially influenced by epithelial cell polarity. We stably transfected the B lymphocyte EBV receptor (CR2/CD21) into Madin-Darby canine kidney (MDCK) epithelial cells used extensively to study effects of cell polarity on infection by both DNA and RNA viruses. CR2/CD21 was detected on both apical and basolateral surfaces of polarized MDCK cells, with predominant expression basolaterally. However, infectivity was up to four-fold greater apically, suggesting that endogenous cell surface molecules, sorted asymmetrically onto polarized plasma membranes, may be involved in EBV entry into MDCK cells. EBV gp350/220, a replicative cycle glycoprotein added to the virus envelope on egress through the cell membrane, was immunolocalized by confocal microscopy to basolateral cell surfaces only. Apical entry of EBV with subsequent basolateral release of newly replicated virus favors systemic infection by viral dissemination to underlying lymphocytic aggregations. Under conditions of long-term culture, latent EBV was not stably maintained in these cells, suggesting that the epithelial phase of acute EBV infection may be transient.

CD21-Mediated Entry and Stable Infection by Epstein-Barr Virus in Canine and Rat Cells

“…Another interesting aspect of this work is the efficient induction of the lytic cycle but failure to synthesize the envelope protein gp350/220 in EBV-infected nonprimate cells. Similar results have recently been reported in transiently EBV-infected MDCK cells (2). The discordance between early and late viral proteins is often seen in human B-lymphocyte cultures (3).…”

“…We have presented evidence that EBV infected three of seven mammalian cell lines in a CD21-dependent manner when CD21 was expressed exogenously. There have been several reports of successful EBV infection of nonprimate mammalian cells by introducing the human CD21 gene, but all were transient infections (1,2,27). This is the first report of stable EBV infection in nonprimate mammalian cells.…”

“…Several attempts have been made to infect nonprimate mammalian cells with EBV (1,2,27), but all failed to establish stable infection. The present study aimed to establish stable EBV infection in nonprimate mammalian cells.…”

Length of Epstein-Barr Virus Termini as a Determinant of Epithelial Cell Clonal Emergence

“…Our experiments stemmed from the unexpected observation, also made by others, that in vitro infection of established epithelial cell lines frequently gives rise to a clonal pattern by EBV TR analysis (3,15). To determine the basis for this outcome, we infected established human carcinoma cell lines with a recombinant EBV whose expression of the neomycinresistance gene would force retention of all viral genomes in cells maintained under antibiotic pressure.…”

“…Here, we present evidence from carcinoma cell lines infected in vitro that suggests that this need not be the case. Instead, EBV clonality postinfection may be a consequence of a selective growth advantage conferred by viral episomes with a minimal number of TRs.Our experiments stemmed from the unexpected observation, also made by others, that in vitro infection of established epithelial cell lines frequently gives rise to a clonal pattern by EBV TR analysis (3,15 ; American Type Culture Collection, Rockville, Md. ), which were determined not to express the B-lymphocyte EBV receptor CD21 (data not shown), were incubated for 24 h with 0.5 ml of Akata culture supernatant containing EBV Neo r and then resuspended in Dulbecco's modified Eagle medium containing 350 g of G418/ml.…”