L25: Retroviridae 2 (Romero) Flashcards
signs of Bovine Leukemia Virus infection
- lymphoms associated infection
- persistent lymphocytosis
Bovine Leukemia Virus eradication efforts
No serious efforts in USA; eradicated in most European and Scandinavian countries
sporadic bovine leukosis/lymphosarcoma associated with BLV infection?
No; usually seen in young bovines
3 forms of sporadic bovine leukosis/lymphosarcoma and CS
1) Juvenile (young calves) –> poor body condition, enlarged LN
2) Thymic (6-24mo.) –> edema in dewlap
3) Cutaneous (occurs in 1-3yr olds) –> lymphomas over thorax/abd
transmission of bovine leukemia virus**
- Horizontal through transfer of viable infected WBCs (milk, insects, blood-contaminated tools)**
- buffalos and sheep may be infected, but not naturally
Bovine Leukemia Virus infection and disease
- most asymptomatic and only revealed through testing for BLV Ab
- animals develop multiorgan lymphosarcomas
- presence of large numbers malignant cells (lymphoblasts) in the blood
Path. of Bovine Leukemia Virus**
- BLV targets B lymphocytes with IgM on surface**
- Monos and mac also infected
- polyclonal expansion of lymphocytes follows infection
- BLV enhances transcription of virus promoter with viral transactivating protein Tax**
BLV tumors-associated condemnation
cow condemned if even 1 tumor found in any location
what percent US cows serum Ab positive for BLV?
30-40%
Dx of Bovine Leukemia Virus
- development of multicentric lymphosarcomas
- test for specific BLV serum Ab
T/F: test and removal strategy for BLV in US in voluntary
T
Prevention/Control of BLV
- test every 3 mo. and eradicate positives
- separate calves from infected cows at birth
Caprine Arthritis-Encephalitis Virus infection
- viral disease of goats
- life-long infection
- erratic shedding
- widespread in US
CS of Caprine Arthritis-Encephalitis Virus
(most infections asymptomatic) arthritis encephalitis (mostly kids) pneumonia mastitis weight loss (wasting)
Caprine Arthritis-Encephalitis Virus infection in kids
- encephalomyelitis or leukoencephalitis
- lameness
- paralysis
- depression, head tilt
- muscle tremors
Transmission of Caprine Arthritis Encephalitis
- Major route = colostrum/milk from infected does**
- virs assoc. with WBCs
- breeding with infected goat
- other methods: in utero, at birth, saliva/resp. secretions
Control/Dx of Caprine arthritis-encephalitis
- Test and remove Ab+ goats
- Serology
- PCR
- remove kids from infected does as soon as born**
- no vaccine/tx**
- quarantine incoming animals
4 syndromes of Equine Infectious Anemia
1) Acute (fever, anemia, jaundice, hemorrhage)
2) Subacute (mod. fever and recovery)
3) Life-long persistent infection (recurrent episodes of CS)
4) Chronic (mild signs to cachexia, anemia, ventral edema)
Path. of Equine Infectious Anemia
- Virus infects macs (life-long)
- Vasculitis and glomerulonephritis may develop (hemorrhagic lesions common**)
- Env glycoprotein mutates –> new varient emerges
- serum from early febrile episodes can neutralize virus from initial infection
Trans. of Equine Infectious Anemia
- mechanical transmission by flies
- iatrogrenic trans. with fomites, transfusions
- transplantal
- milk, saliva, urine, semen
Dx of Equine Infectious Anemia
- Coggin’s test detects Ab against p26
- RT-PCR
Majority of FIV infections occur in what population of cats?
outdoor unneutered male cats
Feline immunodeficiency virus chars.
- causes progressive immune suppression in domestic cats
- increases susceptibility to opportunistic infections by inducing shift from T-helper 1 to T-helper 2 lymphocytes, cytokine disregulation, and suppressing innate and acquired cellular immune response
- causes anergy and apoptosis of lymphocytes in primary lymphoid organs
transmission and landmarks of feline immunodeficiency
- mainly trans. via saliva (biting)
- progression to clinical dz parallels decline in circulating CD4 lymphocytes
- life-long infection
3 stages of FIV-associated disease
1) Acute stage (lymphadenopathy, leukopenia, fever)
2) Long sub-clinical stage (drop in lymphocytes, otherwise asymptomatic)
3) Terminal stage (loss of immune function, 2ary infections, neoplasia, fever)
Common CS of FIV infection
- most due to non-healing 2ry infections
- signs/symptoms called “Feline AIDS”: poor appetite, weight loss, v/d, gingivitis, stomatitis, chronic conjunctivitis, fever/swollen LN
Can DIVA strategy be applied to FIV vaccinated cats?
No
gold standard for FIV dx
virus isolation
Why may young kittens test + for FIV?
maternally-derived Ab (re-test at 6 mo.)
immunological features of FIV
- presence of Ab does NOT correlate with virus clearance or dz progression
- increase in CD8 T cells related to reduced viremia
- WBCs respond poorly with IL-2
- impairment of innate immunity
Control of FIV
- keep cats indoors
- acutely-infected queens my infect kittens through colostrum
- test and removal strategy best!**
- poor cross-protection of vaccines (DIVA concerns**)
Bovine Immunodeficiency virus replicates where?
Non-dividing cells (char. shared by Lentivirus genus of retroviridae)
BIV genome
ssRNA
Path/trans/implications of BIV
- path. uncertain
- iatrogenic trans.
- potential for being used in gene therapy as it is not infectious to humans and transduces a wide range of cells
Maedi-Visna/Ovine Progressive Pneumonia chars.
- literally means “dyspnea wasting”
- affects sheep/goats
- mostly subclinical
- integrates into lymphocytes DNA
- genetically diverse isolates
Trans. of Maedi-Visna/Ovine Progressive Pneumonia
- early in life through colostrum/milk**
- direct contact
- vert. trans. rare
- infected shed virus no matter whether symptomatic or not
- trans. between sheep/goat possible
CS of Maedi-Visna/Ovine Progressive Pneumonia
- mostly asymptomatic
- resp. difficulty
- Neuro signs (paralysis, weakness of hind limbs, etc.)
- mastitis
- arthritis
Epi of Maedi-Visna/Ovine Progressive Pneumonia
- variable prevalence in US
- mortality 20-30% in naive pops.
- co-infection with Jaagsiekte results in more severe CS and inc. trans.
Dx of Maedi-Visna/Ovine Progressive Pneumonia
- Serology
- Detection of proviral DNA
- virus isolation
Control of Maedi-Visna/Ovine Progressive Pneumonia
- only introduce lambs from MVV-free sources
- eradication: separate + lambs at birth, feed newborns with MVV-free colostrum, test q few months, biosecurity, etc.
