3.3 DNA viruses 1 Flashcards
Important families of DNA viruses
-parvoviridae
-circoviridae
-polyomaviridae
-papillomaviridae
important viruses in the parvo family
CPV, FPV, PPV (canine, feline, porcine)
important viruses in the polyma family
APyV
important viruses in the circo family
BFDV, PCVAD
important viruses in the papilloma family
CPV, equine sarcoid
genome structure of parvo and where it replicates. Is it enveloped?
- Single stranded DNA genome,
- Replicate in the nucleus,
- non-enveloped- resistant in the environment
- ~25 nm (small)
are canine and feline parvovirus related? How closely?
- Canine parvovirus 2 (CPV-2) and Feline panleukopenia virus are genetically closely related
- CPV-2 is a host range mutant of Feline panleukopenia virus
–both protoparvoviruses
1976-1978: CPV-2 caused what?
a worldwide epidemic of myocarditis and gastroenteritis
is Canine parvovirus 2 resistant to inactivation? is it stable in the environment?
- Very resistant to inactivation, stable in the environment
where are the receptors for Canine parvovirus 2?
- Receptors on epithelial cells: gut epithelial cells
What is NOT a clinical presentation of CPV infection in dogs between 6 weeks and 6 months old?
a. Myocarditis
b. Acute enteric disease
c. Lymphopenia
d. Skin hyperkeratosis
d. Skin hyperkeratosis
What are target cells of feline panleukopenia virus?
a) Cells of the intestinal crypt
b) Rapidly dividing cells
c) White blood cells
d) All of the above
d) All of the above
note - WBCs and intestinal crypt cells divide quickly
Which of the following statements is CORRECT about Parvoviruses:
a. Small, double-stranded DNA viruses
b. Replicate in the cytoplasm of actively-dividing cells
c. Enveloped virus resistant to harsh environmental conditions
d. All of the above
e. None of the above
f. All except C
g. All except B
SS DNA, rep. in nucleus, non-enveloped
e. None of the above
What is the agent associated with Post-Weaning Multisystemic Wasting Syndrome of swine?
a. Porcine parvovirus
b. SMEDI
c. Porcine circovirus 2
c. Porcine circovirus 2
Which of the following is NOT CORRECT about circoviruses:
a. Non-enveloped virus that is extremely resistant in the environment
b. Replication occurs in the nucleus
c. Porcine circovirus 2 causes a complex disease with multiple syndromes
d. Linear single stranded DNA genome
D. linear stranded DNA
=> circoviruses have a circuloar conformation
Which of the following statements is NOT CORRECT?
a. Both poliomaviruses and papillomaviruses are non-
enveloped viruses that can be easily disinfected with soap
b. Canine papillomavirus causes “warts” and is usually self- limiting
c. Budgerigar fledgling disease can cause high mortality in diseased birds
d. Equine sarcoid is a skin tumor
a. Both poliomaviruses and papillomaviruses are non-
enveloped viruses that can be easily disinfected with soap
>are both naked, resistant in environment
where does canine parvovirus replicate? What does it require?
- Replicates in the nucleus of the infected cell - needs actively dividing cells because it needs to use the DNA replication machinery (fetal, hematopoietic/ lymphoid tissues, intestinal crypts, cardiomyocytes in neonates)
how is canine parvovirus released? What is its associated pathology caused by?
- Release by cell lysis
- Pathology is due to direct destruction of infected cells
pathogenesis of CPV
entry - fecal-oral route
initial replication - thymus, tonsil, retropharyngeal and mesenteric lymph nodes
viremia - days 2-5 post-infection
=>infection of intestinal crypt epithelial cells, bone marrow progenitor cells (high rate of cell division)
=> good antibody response leads to recovery; otherwise, death
=>sheds in feces up to 1 week after recovery
CPV-2 clinical presentation
- Acute, generalized viral infection
- Usually puppies: 6 weeks to 6 months old
- Signs: sudden onset of haemorrhagic diarrhea, vomiting, anorexia and fever, depression, lymphopenia, dehydration
- Mortality is higher in puppies than adult dogs
- Myocarditis (infection in utero or < 2 weeks old, sudden death)
how do we diagnose CPV?
Based on history, clinical signs, positive SNAP test, post- mortem findings
Identification of viral nucleic acid in feces by PCR (used to confirm Snap test)
how can we treat, control, and prevent CPV?
Treatment:
Fluid and electrolytes to replenish what is lost from the diarrhea
Antibiotics to prevent secondary infection
Control and prevention
Disinfection and vaccination
clinical manifestation of feline panleukopenia virus
- Usually inapparent in healthy adult cats
- Acute disease usually in young cats: dehydration, diarrhea, vomiting, anorexia, fever, high mortality in kittens
- Severe and prolonged leukopenia involving all white blood cell elements
- Pathogenesis is very similar to Canine parvovirus 2
pathology of feline panleukopenia virus
Pathology: cerebellar hypoplasia
Infection in the 2 last weeks of pregnancy or 2 weeks old kittens
Neonatal death
Congenital abnormalities: cerebellar hypoplasi
how can we diagnose feline panleukemia virus?
- Presumptive diagnosis
> Clinical signs ( a young cat with dehydration, diarrhea, vomiting, anorexia) - WBC (leukopenia)
- Laboratory diagnosis
> PCR (usually labs have feline diarrhea PCR panels) - Antigen detection in feces by ELISA
how can we treat and control feline panleukopenia?
- No effective treatment
- Antibiotics may help to prevent bacterial complications
- Vaccines: induce protective immunity to prevent the disease (but not infection)
- Likely life-long immunity
does porcine parvovirus survive for a long time in the environment? How does it compare antigenically to other parvoviruses? what species does it infect?
- Very resistant in the environment
- Antigenically different from other parvoviruses
- Infects only swine
what is a major symptom of porcine parvovirus disease?
- Reproductive failure in sows
- Return to estrus or infertility
what type of infection is porcine parvovirus and what is the result of this?
- Transplacental infection
- SMEDI: stillbirth, mummification, embryonic deaths, infertility
what are the physical/ structural characteristics of a circovirus? where does it replicate?
- Circo= viral DNA has a CIRcular COnformation
- Single stranded DNA genome,
- Replicates in the nucleus of rapidly dividing host cell
- Non-enveloped- resistant outside of the host cell
important circoviruses
Beak and feather disease virus
Porcine circovirus 2
characteristics of beak and feather disease. what are clinical signs, and prognosis?
- Infection is often mild or subclinical
- Infected psittacine birds may take weeks, months or years before showing any clinical signs, often depending on age of the bird.
- In diseased birds clinical sign include necrotic (dead) or abnormally formed feathers.
- Once signs are seen, most birds die from secondary infections within 6-12 months.
where do we find porcine circovirus 2? what diseases does it cause?
- Worldwide distribution, ubiquitous in swine
- Porcine circovirus associated disease (PCVAD): different disease manifestations associated with PCV-2
(unknown if it is the only cause) - porcine dermatitis and nephropathy syndrome
what does Porcine circovirus associated disease (PCVAD) cause?
-Post-weaning multisystemic wasting syndrome (PMWS)
- Reproductive Disease
what is Post-weaning multisystemic wasting syndrome (PMWS); what causes it and what are its characteristics and symptoms?
- Multifactorial disease
- Gradual wasting, growth retardation
- Pallor, anemia, jaundice, diarrhea, and inguinal lymphadenopathy
- Lymphoid depletion
-porcine circovirus 2 is agent
what sorts of reproductive disease in porcine circovirus associated with?
- Reproductive Disease
Late-term abortions and stillbirths, early embryonic death or decreased reproductive performances
what are the characteristics of polyomavirus? what does it infect? where does it replicate?
Poly= many Oma= tumor
Affects mammals and birds
Naked (non-enveloped) virus with dsDNA (circular) genome
Replicates in the nucleus
what is budgerigar fledgling disease? what does it infect and what causes it? what are signs/ consequences?
Polyomavirus - Budgerigar fledgling disease
-Avian polyomavirus (not neoplastic)
-Psittacine and passerines
-High mortality (sudden death)
-Absence of feathers, skin lesions (survivors)
-signs of hemorrhage and pale musculature post mortem
what type of genome do papillomaviridae have? what does the name mean? what are its physical characteristcs?
- Papilla (pustule), oma (tumor)
- A circular double stranded DNA genome
- Non-enveloped small virus (~ 50 nm)
what is the pathology of papillomavirus associated with?
- Pathology is associated with cell transformation - carcinomas in humans
are papillomaviruses species specific?
highly
what do papillomaviruses cause in animals?
- Causes infectious papillomatosis (warts) in animals
what is the prognosis of canine papillomavirus? is it common and how is the infection passed? what happens in severe cases?
- Canine papillomavirus I
- Common and usually self-limiting
- Puppies acquire the disease after close contact with other carriers
- SEVERE cases show compromised eating or respiration may need surgical excision
