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Journal of Virology, August 2001, p. 7564-7571, Vol. 75, No. 16
Department of Microbiology-Immunology,
Northwestern University Medical School, Chicago, Illinois 60611
Received 20 February 2001/Accepted 10 May 2001
Infections by low-risk papillomavirus types, such as human
papillomavirus (HPV) type 6 (HPV-6) and HPV-11, induce benign genital warts that rarely progress to malignancy. In contrast, lesions induced
by high-risk HPV types have the potential to progress to cancer.
Considerable information is available concerning the pathogenesis of
high-risk HPV types, but little is known about the life cycle of
low-risk HPV types. Although functionally distinct, both high- and
low-risk virus types infect keratinocytes and induce virion production
upon differentiation. This information suggests that they may share
common mechanisms for regulating their productive life cycles. Using
tissue culture methods developed to study high-risk HPV types, we
examined the ability of HPV-11 to be stably maintained as episomes
following transfection of normal human keratinocytes with cloned viral
DNA. HPV-11 genomes were found to be maintained in keratinocytes for
extended passages in cultures in 14 independent experiments involving
transfection of cloned HPV-11 DNA. Interestingly, the HPV-11-positive
cells exhibited an extended life span that averaged approximately
twofold longer than that of control neomycin-transfected cells. In
organotypic cultures, HPV-11-positive cells exhibited altered
differentiation patterns, but the extent of disruption was less severe
than that seen with high-risk HPV types. In addition, the amplification
of HPV-11 DNA, as well as the induction of several viral messages, was
observed following differentiation of transfected cells in semisolid
media. To determine whether global changes in cellular gene expression
induced by HPV-11 were similar to those observed with high-risk HPV-31
(Y. E. Chang and L. A. Laimins, J. Virol.
74:4174-4182, 2000), microarray analysis of 7,075 expressed sequences was performed. A spectrum of cellular genes
different from that previously reported for HPV-31 was found to be
activated or repressed by HPV-11. The expression of only a small set of genes was similarly altered by both high- and low-risk HPV types. This
result suggests that different classes of HPVs have distinct effects on
global cellular transcription patterns during infection. The methods
described allow for a genetic analysis of HPV-11 in the context of its
differentiation-dependent life cycle.
0022-538X/01/$04.00+0 DOI: 10.1128/JVI.75.16.7564-7571.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Cellular Changes Induced by Low-Risk Human
Papillomavirus Type 11 in Keratinocytes That Stably Maintain
Viral Episomes
*
Corresponding author. Mailing address: Department of
Microbiology-Immunology, Northwestern University Medical School, 303 East Chicago Ave., Chicago, IL 60611. Phone: (312) 503-0648. Fax: (312)
503-0649. E-mail: lal{at}merle.acns.nwu.edu.
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