Exam 2 - Family: Parvoviridae Flashcards
Family: Parvoviridae - Properties
Nonenveloped, small size (18-25 nm), virion capsid (60 subunits, T=1), Single-stranded DNA genome which are linear, very stable, replicates in the nucleus of dividing cells
Subfamily: Parvovirinae
Five genera that infect vertebrates:
- Parvovirus
- Dependovirus
- Amdovirus
- Erythrovirus
- Bocavirus
Genus: Erythrovirus
Fifth disease, slap cheek rash
Genus: Erythrovirus - Properties
- Replicate autonmously
- Include human parvovirus B19
- Causes mild rash illness, also called infectiosum in children
- Aplastic anemia in children
- Painful joints
- Different from the parvovirus seen in dogs and cats. No evidence of transmission of B19 to humans from dogs and cats, or vice versa
Genus: Dependovirus
- Unable to replicate except in the presence of a helper virus, usually an adenovirus
Genus: Bocavirus
Contain a third ORF (Open Reading Frame) between non-structural and structural coding region
Genus: Parvovirus - Properties
Diseases include:
- Feline parvovirus
- Canine parvovirus 1
- Canine parvovirus 2
- Porcine parvovirus
- Mink enteritis virus
Cannot replicating in stationary cells. Occurs in cells that pass through mitotic S phase.
Feline parvovirus
Feline Panleukopenia (FPV)
FPV - Synonyms
Feline distemper, feline infectious enteritis
FPV - Host
Highly contagious, often fatal disease of cats, severe in kittens
FPV - Transmission
Are infected oro-nasally by exposure to infected animals, their feces, secretions, or contaminated fomites. In-utero transmission, mechanical transmission by flies.
FPV - Pathogenesis
Replicates in pharyngeal lymphoid tissues. Cell-associated viremia to other organs and tissues via blood stream.
FPV - Panleukopenia
- Hallmark of the disease
- More severe the leukopenia, the poorer the prognosis
- Destruction of all white blood cell elements
- Cells present in the circulation (consequence of virus absorption and cytotoxic lysis) as well as those in lymphoid organs are destroyed
FPV - Enteritis
Loss of cells from tip of villus continues as a normal process. However, since virus replication and destroys cells of crypts, there is no replacement of the lost absorptive cells at tips of the villi with cells from the crypts. This results in shortening of intestinal villi, marked villus blunting and fusion, malabsorption and diarrhea.
FPV - Early in-utero infection
Results in early fetal death and resorption with infertility, abortion, birth of mummified fetuses
FPV - Infection closer to end of gestation
Birth of live kittens with varying degree of damage to the late developing neural tissues. Variable effects on kittens from the same litter.
FPV - CNS Infection
Damage to optic nerve, retina, and cerebellar
FPV - Cerebellar hypoplasia
Usually observed in fetuses infected during the last 2 weeks of pregnancy and the first two weeks of life. Lysis of mitotic cells of the external germinal layer. Impaired cerebellar development.
FPV - DIC
Kittens with FPV infection are also susceptible to secondary gram negative bacterial infection.
FPV - Clinical signs
- 3 to 5 months
- Incubation period ranges from 2-10 days
- Fever, depression, anorexia, rough coat, repeated vomiting, profuse, persistent and frequently blood diarrhea
FPV - Diagnosis - Hematology
- Leukopenia, neutropenia more consistent than lymphopenia
- Virus isolation in cell culture
- Fecal viral antigen testing using immunochromatographic test kit or ELISA
- PCR for detection of viral DNA in tissues
- Direct hemagglutination
FPV - Treatment
- Nursing care, fluid therapy, withholding in early stages to less vomition and slow down mitotic activity of cells.
- Broad spectrum antibiotics to prevent secondary bacterial infection
FPV - Vaccination
MLV and inactivated vaccines
FPV MLV should NOT be administered to
Pregnant queens, immunosuppressed cats, sick cats, and kittens less than 4 weeks old