virus (MHV) altered host resistance to experimental infection with a second ..... MHV-free or. MHV-infected mice. The peritoneal. MO compartment was also.
Journal
of Leukocyte
Biolo
39:559-565
(1986)
Effect of Inapparent Murine Hepatitis Virus Infections on Macrophages and Host Resistance Walla
L. Dempsey,
Department Philadelphia Epidemiology Connecticut
Abigail
L. Smith,
and Page
S. Morahan
of Microbiology and Immunology, Medical College of Pennsylvania, (WL.D., P.S.M.); Section of Comparative Medicine and Department of and Public Health, Yale University School of Medicine, New Haven, (A.L.S.)
Inapparent infections of mice with murine hepatitis virus (MHV) altered host resistance to experimental infection with a second virus, encephalomyocarditis virus (EMC), reduced the protective effects of exogeneously administered interferon against EMC infections, and it altered macrophage ectoenzyme phenotypes in two macrophage populations. Resident peritoneal macrophages from mice experimentally infected with one of two strains of MHV also demonstrated altered ectoenzyme phenotypes. These data demonstrate that inapparent infections with MHV alter several host resistance and macrophage parameters and directly demonstrate that effects of inapparent MHV infection on macrophage parameters can be reproduced experimentally.
Key words:
viral infections, mononuclear derived macrophages
phagocytes,
ectoenzymes,
bone marrow
INTRODUCTION Inapparent viral infections pronounced impact on various although potential studies natural
the immunomodulatory effects of inapparent are not fully appreciated. infection of mice with
coronaviruses, phage (MO) onstrating
phenotypic with
Received
October
Reprint
requests:
Henry
Avenue,
1986
Alan
changes
rodents have been results [4,6,9,10,11,201.
reported
to have Nevertheless,
to a second We further
in murine
peritoneal
virus infection and changes substantiate these findings MO
after
experimental
macroby deminfection
MHV. 30, Walla
1985: accepted L.
Dempsey.
Philadelphia,
R. Liss,
Inc.
PA
a
effects of many viruses are well established, the viral infections on immunologic and host resistance In the present study, we document that inapparent murine hepatitis virus (MHV), a ubiquitous group of
alters host resistance biochemical parameters.
of mice
©
of laboratory experimental
December Department
19129.
20, 1985. of Anatomy.
Medical
College
of Pennsylvania.
3200
560
Dempsey,
MATERIALS
AND
Smith,
and
Morahan
METHODS
Mice The I (Charles
effects River
Gilmore, the date
of inapparent Breeding
CA). Specific of arrival, for
Biocon
Inc.
pathogen-free seroconversion
Rockville,
,
infections with Labs, Kingston,
MD).
specific pathogen-free ME). All mice were
MHV NY)
mice were monitored to MHV and Sendai
Experimental
4-wk-old maintained
were documented and B6C3 Fl
infections
female BALB/cByJ on a 12-hr light/dark
in female (Simonsen
routinely, viruses
of
MHV
CDLabs,
including on (Elisa methodwere
initiated
in
mice (Jackson Labs, Bar Harbor, cycle, provided food and water
ad libitum, and cared for according to National Institutes of Health (NIH) guidelines. Infected and control BALB/cByJ mice were housed in separate facilities within microisolator
cages
(Lab
biological
safety
Microbial
Infections
one
Groups of four
Mortality data tally
Products,
ofseven dilutions
was
monitored
daily,
and
strain
the
was
of Peritoneal
MO
peritoneal
cells
Resident
5 ml of heparinized
by visual
Preparation Bone
essential 929 cell
marrow
[21].
lation.
The
nuclei
after
Ectoenzyme
lized
opened
only
Marrow cells
All
number
in a class
II
lysis
of
MO
were
were
stained by
of the cells
with
cells
3%
pantropic
MHV-JHM
TClD0.
Successful
[5].
serology
of the
survival
peritoneal
cavity
phosphate-buffered
with saline,
cytocentrifuge
adherence
preparations
for
2 hr
as
of
previously
(BMDMO)
cultured
performed
the overall
infected experimenThe low passage,
l0
IL)
for
10% fetal bovine serum, as a source of colony
adherent
the
with VR129).
by mechanical counting with a ZBM FL), and differential cell counts were
isolated
Derived
assays
and
Chicago,
determined Hialeah,
were
isolated
from
mice were MHV-JHM).
by lavage
Labs,
of Dif-Quik
MO
medium containing conditioned medium
described
calculated
orally,
obtained
Abbott
examination
Resident
of Bone
was
Each mouse received immunofluorescence
were
(2 U/mI,
cells. [151.
LDo
inoculated
pH 7.2). The number of cells was Coulter counter (Coulter Instruments, peritoneal described
were
mice were injected intraperitoneally virus (EMC) (ATCC strain
.
MHV-RI
determined
which
procedure I 161 BALB/cByJ strains of MHV (MHV-RI or
strain was inoculated intranasally. infections were monitored by indirect Preparation
NJ),
to eight female CD-i of encephalomycarditis
by the Reed-Muench with one of two
enterotropic
Maywood,
cabinet.
on was
cetrimide
the
up
to
7 days
10% horse stimulating
resulting
determined
as reported
in alpha-minimal
serum, factor
adherent by
counting
by Stewart
and 10% Las previously
BMDMO the
popu-
number
of
[211.
Determination
Adherent cells cell membranes
were were
lysed with 0.05% Triton X-lOO and aliquots analyzed for protein content, 5’ nucleotidase
and alkaline phosphodiesterase-I cording to the BioRad procedure was determined by measuring
of the solubi(5’N) activity,
(APD-I) activity. Protein content was assayed ac(Bio-Rad Labs, Rockville Center, NY). S’N activity the hydrolysis of 3H-adenosine monophosphate, and
MHV, TABLE Activity
Macrophages,
1. Effect of Inapparent in BMDMO
MHV
Cells
Host
Resistance
Infection
BMDMO
7-day
BMDMO activity
a5,
cells).
The
in protein
the
0.05
expressed
specific
content
bRepresents