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Infection and Immunity, June 2001, p. 4065-4071, Vol. 69, No. 6
Department of Veterinary Microbiology and Pathology,
Washington State University, Pullman, Washington
99164-7040,2 and Department of
Internal Medicine and Microbiology, College of Medicine, University
of Iowa, Iowa City, Iowa 522421
Received 30 October 2000/Returned for modification 8 December
2000/Accepted 7 March 2001
Infection of mammalian skeletal muscle cells by Trichinella
spiralis causes host nuclei to become polyploid (ca. 4N)
and abnormally enlarged. It has been postulated that this enlargement
reflects an infection-induced elevation of host transcription.
Anthelmintic treatment of T. spiralis-infected rodents
with mebendazole (MBZ) causes a reduction in the size of infected cell
nuclei and a significant reduction in the total RNA content of
individual infected muscle cells. A monoclonal antibody to the large
subunit of RNA polymerase II (Pol II) was used here to assess the
effects of infection on Pol II levels in isolated infected cell nuclei.
Pol II was localized to speckle domains in isolated infected cell
nuclei. Similar domains have been previously localized to sites of RNA
synthesis or processing. When compared to the levels in nuclei from
other, uninfected host cells, speckle-localized Pol II (SL-Pol II)
levels were significantly elevated in infected cell nuclei by a mean of
3.9- to 6.8-fold. Nuclear antigens (NA) recognized by antibodies
against T. spiralis localized to infected cell nuclei.
By use of confocal microscopy, a subpopulation of NA was found
colocalized with most speckle domains defined by Pol II. MBZ treatment
of chronically infected mice, which depletes NA from infected cell
nuclei, caused a significant depletion of SL-Pol II from infected cell
nuclei. Control nuclei had a mean of 70% more SL-Pol II than
MBZ-treated nuclei. The mean residual level of Pol II in these
polyploid nuclei remained elevated by 120% over the level in 2N
control nuclei. These observations may indicate two distinct effects of
infection on Pol II levels in host cells.
0019-9567/01/$04.00+0 DOI: 10.1128/IAI.69.6.4065-4071.2001
Copyright © 2001, American Society for Microbiology. All rights reserved.
Trichinella spiralis-Infected Muscle
Cells: Abundant RNA Polymerase II in Nuclear Speckle Domains
Colocalizes with Nuclear Antigens
*
Corresponding author. Mailing address: Department of
Veterinary Microbiology and Pathology, Washington State University,
P.O. Box 647040, Pullman, WA 99164-7040. Phone: (509) 335-6040. Fax: (509) 335-8529. E-mail: djasmer{at}vetmed.wsu.edu.
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