Pathogenesis of Sialodacryoadenitis in Gnotobiotic Rats

Abstract

The pathogenesis of sialodacryoadenitis was studied in gnotobiotic CD rats inoculated intranasally with the causal virus. Virus replication was detected sequentially in the nasopharynx, tracheobronchial tree, cervical lymph nodes, submaxillary and parotid salivary glands, exorbital gland, and Harderian gland. Acute rhinitis appeared within 2 days after inoculation, and salivary glands had lesions in 4 days. Early changes in salivary and exorbital glands were characterized by necrosis of ductal epithelium, which rapidly progressed to widespread acinar necrosis, marked inflammation, edema and total effacement of glandular architecture. Harderian glands also had massive necrosis of tubuloalveolar units. Repair in all glands was characterized by marked squamous metaplasia of tubuloalveolar units. Repair in all glands was characterized by marked squamous metaplasia of ducts. Neutralizing and complement-fixing antibodies were detected in 7 days, and there was a concomitant decrease in tissue-virus titers. There was no detectable evidence for hematogenous spread of virus or for retrograde infection by way of major salivary ducts.

Sequential Changes in the Harderian and Exorbital Lacrimal Glands in Wistar Rats Infected with Sialodacryoadenitis Virus

“…Animals were housed two per cage in polycarbonate cages with hardwood bedding, and fed a commercial ration (Purina Rodent Laboratory Chow, Ralston Purina Co., St. Louis, MO). Rats were inoculated intranasally with SDA virus as previously described.12 Inoculated and control rats were killed at 6, 7,8,10,12,14, and 21 days post-inoculation (pi) by an overdose of sodium pentobarbital (Somnotol, MTC Pharmaceuticals, Mississauga, Ontario) administered intraperitoneally. Blood was collected for serology by cardiac puncture.…”

Ocular Mucosal Immunity

“…These viruses have been identified in the lacrimal and/or salivary tissues of Sjögren's patients (Burns, 1983;Fox et al, 1986;Fox, 1988;Krueger et al, 1990;Garry et al, 1990;Mariette et al, 1991;Pflugfelder et al, 1993;Tsubota et al, 1995;Pepose et al, 1996) and may possibly stimulate the inappropriate epithelial cell human leukocyte antigen-DR and Toll-like receptor expression, T helper/inducer cell activation, B cell hyperactivity, and autoantibody production evident in these affected tissues (Moutsopoulos and Talal, 1987;Maini, 1987;Fox, 1988;Homma et al, 1994;Berglova et al, 2011;Lambiase et al, 2011). In support of this possibility, certain viral infections in experimental animals exert a striking effect on the lacrimal gland and induce a periductular infiltration of plasma cells, lymphocytes, and macrophages; distinct nonsuppurative periductular inflammation; significant interstitial edema; widespread necrosis of the acinar and ductal epithelium; degenerative and atrophic alterations in epithelial cells; diminished tear flow; and keratoconjunctivitis sicca (Jacoby et al, 1975;Green et al, 1989). Moreover, herpes viruses (i.e., cytomegalovirus) and coronaviruses (i.e., sialodacryoadenitis virus) may invade and replicate in rat lacrimal gland acinar cells Wickham et al, 1997), Epstein-Barr virus may bind to specific receptors in ductal epithelium of the human lacrimal gland (Levine et al, 1990), and HIV infection may predispose patients to keratoconjunctivitis sicca (Couderc et al, 1987;Ulirsch and Jaffe, 1987;De Clerck et al, 1988;Lucca et al, 1990;Neves et al, 1994).…”

Microbiological Quality Control for Laboratory Rodents and Lagomorphs

“…Selected specimens may then be examined microscopically for histopathological changes after tissue sections are stained with hematoxylin and eosin (Weisbroth et al, 1998). Microbial antigens or nucleic acid in tissue sections can be specifically stained by immunohistochemistry (Allen et al, 1981;Brownstein and Barthold, 1982;Cera et al, 1994;Hall and Ward, 1984;Jacoby et al, 1975;Sundberg et al, 1989) or in situ hybridization (Gaertner et al, 1993;Jacoby et al, 1995), respectively. Microbial antigens or nucleic acid in tissue sections can be specifically stained by immunohistochemistry (Allen et al, 1981;Brownstein and Barthold, 1982;Cera et al, 1994;Hall and Ward, 1984;Jacoby et al, 1975;Sundberg et al, 1989) or in situ hybridization (Gaertner et al, 1993;Jacoby et al, 1995), respectively.…”