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1. Adenovirus
- a. DNA Virus
- b. Antigenically related to mouse adenovirus (MAdV-2); however rat cannot be infected with it
- c. Clinical signs: none
- d. Path: Intranuclear inclusions in small intestine enterocytes
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2. Herpesvirus: Rat Cytomegalovirus
- a. DNA Virus
- b. Not antigenically related to mouse CMV
- c. Clinical signs: Salivary and lacrimal glands ?
- d. Path: Cytomegaly with intracytoplasmic and intranuclear inclusions in ductal epithelium of both salivary and lacrimal glands
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3. Polyoma Viral Infection
- a. DNA Virus
- b. Serologically distinct from polyoma and K virus of mice
- c. CS: Athymic nude (rnu) rats developed wasting disease, pneumonia, and parotid sialoadenitis vs. euthymic rats did not develop the disease
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4. Parvovirus: Rat Virus, H-1 Virus, Rat Parvovirus 1 (RPV-1), Rat Minute Virus 1 (RMV-1)
- a. DNA Virus
- b. Family Parvoviridae
- c. 3 major genetic/antigenic groups: (1) Kilham�s rat virus (RV, H-3, X-14, RV-Y); (2) Toolan�s H-1 (H-1 and HT); (3) Rat parvovirus ; Distinct from mouse parvovirus
- d. CS: RV-most pathogenic (dyspnea, cyanotic scrotums, muscle weakness, reduced litter size, runted litters, and fetal/neonatal death); RPV-non-pathogenic, asymptomatic but persistent
- e. Path: Gross: Loss of body fat, congestion of lymph nodes, and scrotal hemmorhage; Hemmorhage of brain, testes in older rats but not enteric sites like cats and dogs. Infects rapidly growing cells (vascular epithelium, lymphoreticular and hematopoietic tissues, developing cerebellum and liver
- f. Diagnose: PCR-mesenteric lymph nodes remain positive, Serology (ELISA, IFA, MFIA). Unable to detect using hemagglutination inhibition (HI) assay because doesn�t have homologous cross-reacting antigens (VP1 and VP2); with RV or H-1 but possesses NS1 and NS2 antigens
- g. Biologics: Infect dividing cells (tumor cell lines and tumor virus stocks) from lab rats
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5. Poxvirus
- a. DNA Virus
- b. Reported to occur in rats from Europe and Russia; Distinctively different from ectromelia virus; Seropositive for cowpox virus
- c. CS: Subclinical to dermal lesions and respiratory lesions
- d. Path: Interstitial pneumonia; focal inflammatory lesions in upper respiratory tract
- e. Zoonotic, in addition to felines being susceptible
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6. Coronavirus: Sialodacryoadenitis and Parker�s Rat Coronavirus
- a. RNA Virus
- b. Coronavirus is an RNA virus with 2 strains identified to cause disease in rats. Rat coronavirus (RCV) causes respiratory infection while sialodacryoadenitis virus (SDAV) infects the upper respiratory tract, Hardarian and exorbital lacrimal glands, and the submandibular and parotid salivary glands. The SDAV strain causes clinical disease; Highly contagious
- c. CS: Intermandibular swelling (swollen salivary glands) almost diagnostic; Will see rat with swollen neck (Fig 2.8 PB), sniffling, blepharospasm, epiphora, and porphyrin discharge (especially rats with SDAV).
- d. 2 Disease Types: First associated with breeding colonies where preweanling animals display ocular signs; Second associated with postweanling-to-adult rats with sudden clinical signs (cervical lymphadenopathy)
- e. Highly contagious
- f. Path: Harderian (gray-yellow foci), swollen cervical lymph nodes; eye lesion with inflammation (Know Fig. 9 BB p. 145)
- g. Athymic nude rats are particularly susceptible
- h. Diagnosis: Microscopic examination, PCR, Viral Isolation, IFA, ELISA
- i. Interferes with research (weight loss, decreased reproductive efficiency, chronic ophthalmic problems, increased mycoplasma secondary infection).
- j. 6-8 week period to allow virus to spread to all animals (rats shed for 1 week) or suspend breeding
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7. Hantavirus
- a. RNA Virus
- b. Zoonotic
- c. Family Bunyaviridae
- d. Rattus norvegicus (natural host for the Seoul Hantavirus that causes HFRS in people), R. rattus, and genus Peromyscus are susceptible
- e. 2 major lineages in humans: Hemorrhagic fever and renal syndrome (HFRS) and Hantavirus pulmonary syndrome. Humans are incidental hosts (TM via rat urine). Humans develop fever, thrombocytopenia, and capillary leakage.
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8. Rat Respiratory Virus (a.k.a. Idiopathic pneumonitis)
- f. RNA Virus
- g. Charles River led a study that has led to the conclusion that Pneumocystis carinii (Pc) is the causative agent for interstitial pneumonia in laboratory rats, previously known by the working name "rat respiratory virus" or "RRV".
- h. Diagnosis: Serology (IFA only) and virus isolation
- i. CS: asymptomatic
- j. TM: aerosol and/or dirty bedding
- k. Gross: Scattered brown to grey areas on pleural surface; Histo: Interstitial pneumonia, syncytial cells, perivascular cuffs distributed in lungs
- l. Control: Rederivation
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9. Paramyxovirus: Pneumonia Virus of Mice (PVM); Mouse Pneumovirus
- m. RNA Virus
- n. Family paramyxoviridae
- o. PVM has affinity to respiratory tract; Presence of interstitial pneumonia and perivasculitis
- p. Complication in enzootically infected colonies
- q. Infect mice, rats, hamsters, gerbils, guinea pigs, and rabbits
- r. Co-pathogen with Mycoplasma pulmonis and has possible interspecies transmission
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10. Sendai Virus (Parainfluenza 1)
- s. RNA Virus
- t. Family paramyxoviridae
- u. Rats, mice, hamsters and seroconversion in guinea pigs
- v. Highly contagious
- w. CS: Acute stage: Rhinitis, focal to diffuse necrosis of respiratory epithelium; Reparative stage: Proliferation and regeneration of target epithelium. Otherwise animals are usually asymptomatic. May see acute bronchitis and brochiolitis or reduced production and litter sizes
- x. Path: Lesions not specific however inclusions in airway cells and syncytia are very suggestive of SV
- y. Coinfection with Mycoplasma pulmonis, CAR bacillus, Pasteurella and pneumonia virus of mice
- z. Diagnosis: Virus isolation
- aa. Prevention: Mouse and rat antibody testing should be done on all biologics
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11. Pircornavirus: Rat Cardioviruses (MHG and RCaV)
- bb. RNA Virus
- cc. MHG virus induces neurological disease in experimentally inoculated suckling rats and mice and is closely related to MEV (mouse encephalomyelitis)
- dd. Another isolate from Wistar rats in Japan was characterized by reverse-transcriptase PCR and found different sequences from MEV-GDVII, and therefore called �rat cardiovirus� RCaV. Asymptomatic however in rats and mice inoculated intracerebrally.
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12. Rotavirus: Infectious Diarrhea of Infant Rats (IDIR)
- ee. RNA Virus
- ff. Rotavirus like agent that is morphologically identical but antigenically distinct from most rotaviruses
- gg. Human origin
- hh. CS: Suckling rats develop diarrhea and/or transient growth retardation; Rats are susceptible to disease up to 12 days old and then resistant after 2 weeks old
- ii. Path: Stomach contains milk curd; Histo: Pathognomonic epithelial syncytia (Figure 2.16 PB). This is diagnostic for IDIR.
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13. Reovirus
- jj. RNA Virus
- kk. Mice are the only laboratory species susceptible to reovirus-induced disease
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14. Retrovirus
- ll. RNA Virus
- mm. Minimal, practical significance however these viruses have been manipulated experimentally by combining murine leukemia virus and other rat leukemia viruses to form defective rat sarcoma viruses.
- nn. Harvey and Kirsten sarcoma agents are common sarcoma viruses of rat origin
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