Multisystemic viral diseases of cats Flashcards
(129 cards)
1
Q
Feline Leukemia virus conditions
A
Lymphomas, Leukemia, and immunosuppression
2
Q
lymphomas
A
solid lymphoid tumors composed of malignant proliferating lymphocytes
3
Q
leukemia
A
myeloproliferative tumor of blood and bone marrow
4
Q
distribution of feline leukemia
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worldwide
most important viral disease of cats
5
Q
most important viral disease of cats
A
Feline leukemia/lymphoma
6
Q
classify feline leukemia/lymphoma
A
caused by feline leukemia virus
retrovirus
family Retroviridae
Genus Gammaretrovirus
7
Q
subtypes of FeLV
A
3 subtypes: subtype A, B, and C
can be isolated singly or in combination in disease (A+B)
8
Q
antigens associated with FeLV
A
4 proteins
1) p27: major internal structural protein, detectable by ELISA
2) gp70: envelope glycoprotein, neutralizing antibodies bind gp70, provides basis for subtypes
3) p15E: envelope glycoprotein, immunosuppressant
4) FOCMA: Feline oncorna cell membrane associated antigen: protein present on surface of TRANSFORMED cells from FeLV infection
9
Q
what protein serves as basis for subtype differentiation of FeLV>?
A
gp70
10
Q
which protein of FeLV does ELISA detect?
A
p27
11
Q
What protein acts as an immunosuppressant with FeLV?
A
p15E
12
Q
which protein of FeLV do neutralizing antibodies bind to?
A
gp70
13
Q
what is the significance of FOCMA?
A
Feline oncorna cell membrane associated antigen
A protein that is only present in cells that have BEEN TRANSFORMED by FeLV… virus encoded tumor specific antigen
antibodies to this antigen induces lysis of FeLV transformed cells only
14
Q
Is FeLV very environmentally resistant?
A
NO
labile virus- susceptible to drying and disinfectants
15
Q
What environments have the highest FeLV rate?
A
higher incidence in urban cats (50%)
MULTI CAT HOUSEHOLDS are the highest incidence of infection (30% viremic)
16
Q
How do cats transmit FeLV?
A
saliva (MUTUAL GROOMING, sharing of food/water bowl)
loving transmission
but also milk, urine, feces
17
Q
Is FeLV contagious?
A
yes
18
Q
what is the most susceptible type of cat to FeLV?
A
Young cat with prolonged exposure to a high dose of virus
19
Q
what age is most susceptible to FeLV?
A
the younger, the more susceptible to develop disease
20
Q
where does FeLV replicate?>
A
lymphoid tissue of oropharynx
21
Q
does FeLV cause viremia?
A
YES
22
Q
what is the time frame to develop neutralizing antibodies to FeLV??
A
develop Ab to gp70
if cats develop Ab within 3 weeks, they get over infection
if weak/no Ab produced, cats become persistently infected and 80% chance to die of FeLV associated disease within 3 years
23
Q
look at the 2 charts of FeLV transmission
A
_
24
Q
What is the ratio of FeLV neoplasia deaths to ono-neoplastic FeLV deaths?
A
for every cat that dies of FeLV neoplasia, 2.6 die of non-neoplastic FeLV complications
25
% of 16 week old kittens that develop viremia, transient viremia, and persistent viremia
15% chance of no viremia
35% chance of transient viremia
50% chance of persistent viremia
26
what percentage of all feline tumors are caused by FeLV?
| What percentage of feline HEMATOPOIETIC tumors are caused by FeLV/
FeLV is responsible for 30% of all feline tumors
FeLV is reponsible for 90% of all hematopoietic tumors
27
most common signs of FeLV infection
```
loss of appetite
progressive weight loss
anemia
persistent fever
gingivitis
lymphadenopathy
```
28
lymphomas
solid tumors consisting of accumulations of proliferating transformed malignant lymphocytes
29
what color are lymphoma masses in cats?
cream-white with red stippling on the cut surface
30
types of lymphomas from FeLV
1) multicentric- generalized lymphoma
2) Alimentary lymphoma (older cats, negative for FeLV ELISA, GI signs)
3) Thymic or Mediastinal Lymphoma (younger cats, can cause swallowing difficulties and pleural effusion)
4) unclassified lymphomas- miscellaneous category
31
what is the most common type of leukemia caused by FeLV?
Acute lymphocytic leukemia is most common
32
what is the most important presenting sign of leukemia from FeLV?
Anemia
33
Non-neoplastic diseases caused by FeLV?
non-regenerative anemia (normocytic, normochromic... 60-70% of cats presented with this syndrome are viremic... most commonly associated with subtypes A+C)
Enterocolitis (panleukopenia-like syndrome)
Thymus atrophy
Immunosuppression
Reproductive failure (seen in catteries, infertility)
34
Diagnosis of FeLV?
History (most important consequence of FeLV is immunosuppression)... refractory anemia is most important sign
Clin Path (leukemia [high WBC], lymphoblasts, NORMOCYTIC/NORMOCHROMIC ANEMIA)
pathology (lymphomas with cream-white color with red stippling on cut surface)
virus isolation
detection of viral nucleic acid (PCR detects proviral DNA, RT-PCR detects viral RNA, SNAP test)
Detection of viral antigen (ELISA/SNAP to detect p27 in blood, IFA)
35
What does the ELISA detect?
detects p27 antigen of FeLV in blood
DETECTS ANTIGENEMIA NOT VIREMIA
therefore, positive tests does not mean viremic
36
What do IFA tests detect for FeLV?
immunofluorescent antibody test
detects FeLV antigens on virus infected lymphocytes
37
How good is the IFA to detect FeLV viremia?
98% of cats positive by IFA are viremic
38
How good is ELISA to detect FeLV viremia?
70% of cats positive by ELISA are viremic
39
does a negative ELISA or IFA rule out FeLV?
no because of presence of non-virus producing LSA tumors
40
What are the possibilities for a negative ELISA
non-viremic, not exposed, or immune to FeLV
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What are the possibilities for a positive ELISA
may be viremic
42
What if the cat is positive for ELISA and positive for IFA?
cat is VIREMIC and CONTAGIOUS
98% remain IFA positive for life
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What if the cat is positive for ELISA but NEGATIVE for IFA?
DISCORDANT CAT
30% of ELISA positive cats are "Discordant Cats"
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what are the causes of Discordant cats
typically test positive on initial tests, but then negative on subsequent tests
may be faulty ELISA
may be early in phase of infection (retest in 1 mnth)
may be immune cat with sequestered lesion
45
What is a sequestered lesion for FeLV?
can be present in healthy latently infected or in discordant cats
small foci of infected lymphocytes... immune response (neutralizing Ab) keeps virus in sequester from replication
46
what can induce sequestered lesions from causing antigenemia/replication?
stress
| corticosteroid therapy
47
why is serological detection of FeLV pointless?
seropositive test indicates either that cat has recovered from infection or been vaccinated (does not obtain infection status of cat)
seronegative cat means cat 1)never was infected... or 2) may have FeLV (since diseased cats do not mount an Ab response well)
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Vaccination for FeLV
- whole virus inactivated vaccine
- disrupted virus vaccine with adjuvant
- genetically engineered gp70 with adjuvant
- recombinant (live)canary poxvirus with FeLV gene inserted
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vaccination protocol
vaccinate at 10-12 weeks with 2 doses and booster annually
vaccine prevents tumor, but cats can still become latently infected
vaccine can induce soft tissue sarcoma at injection site
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control program
test and removal program in shelters
- test all cats... if neg, retest after 3 months... if still negative then FeLV negative
- if FeLV exists in cattery, all cats that test positive should be removed... retest after 2 months (and every 3 months thereafter)
51
how quickly can we clear a cattery of FeLV
within 6 months
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Treatment of FeLV
chemotherapy- cyclophosphamide + vincristine + prednisone
or treat with AZT to decrease amount of virus shed
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Feline Sarcoma Virus
endogenous virus
highly oncogenic, defective virus associated with tumors
~fibrosarcoma of skin
carry v-onc gene that replaces part of ENV Gene
Lack capsid and envelope proteins
can hijack FeLV capsid and leave the cell this way
54
FIV
classify
any subtypes?
Feline Immunodeficiency Virus
caused by a retrovirus within genus lentivirus
3 subtypes in US (differentiated by envelope glycoproteins)
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FIV family and genus
family Retroviridae, genus Lentivirus
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what percentage of clinically ill cats test positive for FIV
4-25%
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transmission of FIV
fighting disease
biting during cat fights OR saliva contamination of wounds OR blood transfusion
- virus infects and circulates in CD4 Th cells as a PROVIRUS (integrated int he chromosome)
- also present in blood as free virus
- also present in saliva
58
Is a blood transfusion a possible route of infection?
YES
because it infects Th cells, transmitted lymphocytes are infectious ... also free virus in blood would infect
59
how common is horizontal transmission of FIV in multi-cat housholds?
infrequent
60
what gender and age of cats are more commonly infected with FIV?
2-3X higher incidence in males than females
Adults >6 years more often infected than kittens
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recap of transmission of FIV
```
fighting
saliva contamination of wound
iatrogenic/needle/blood transfusion
transplacental
transmammary
```
62
pathogenesis of FIV
after primary infection, virus replicates in lymphocytes within lymnphoid tissue
-THYMUS is primary site of replication
-FIV infects and replicates in T-cells (especially in Th cells/CD4), but eventually also infects B cells and mononuclear cells
-viremia occurs as result of primary infection
host mounts solid immune response within 2-4 weeks
-viremia decreases, infection goes latent
-latent period can last several years (chonically infected)
-during latent chronic period, FIV replicates in lymphocytes and can be isolated from lymphocytes... however, higher level of virus replication occurs during stress and episodes of illness
63
what triggers FIV out of latent chronic phase?
stress or other infection/illness
64
what clin path is seen with FIV infection?
progressive disruption of immunity
marked decrease in CD4 cells, disruption in cytokine production
secondary infections with resident microflora occur on skin and mucosal surfaces of chronicall infected cats
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what cats have more severe FIV infections?
young cats
| cats with FeLV infections too
66
clinical signs of FIV: 3 phases
1) acute phase
- may go unnoticed, fever with malaise (and general lymphadenopathy)
2) asymptomatic phase
- lasts weeks,months, or years
3) terminal phase
- "wasting syndrome"... stomatitis and gingivitis common... most consistent neurological sign is behavioral changes, but also paresis and seizures
67
What is the most common neoplasia associated with FIV?
Lymphomas of B-cell origin
68
Diagnosis of FIV
History
-older male cat with recurrent infections, stomatitis/gingivitis, abnormal behavior
Clin Path
Pathology... NOT (none are specific for FIV)
-ANEMIA, NEUTROPENIA, and LYMPHOPENIA are seen in 1/3 of ill cats
Virus Isolation (difficult)
Detection of viral antigen (NOT DONE)
Detection of Virus/Viral Nucleic Acid
-RT-PCR to test for FIV provirus (viral DNA) in lymphocytes
detection of circulating Ab (serology)
-IgG response... ELISA test
69
what is the most important test to diagnose FIV infection?
serology- look for Ab in blood (IgG)
ELISA
70
when is IgG detectable to FIV?
within 8 weeks post infection, remain seropositive from then on
... cats in acute phase may be seronegative because they haven't had enough time to develop IgG, so retest in 6 weeks
71
If a cat is seropositive, assume that RT-PCR positive
_
72
If seropositive on ELISA, how long do they stay seropositive?
FOREVER, through all 3 phases of infection
exceptions:
some cats may become seronegative during terminal stage of infection
kittens are seropositive if they acquire maternal antibodies from a positive dam (retest in 6 months)
73
major drawback of ELISA test/serology?
Since we are detecting IgG (not IgM), we cannot differentiate current infection from vaccinated cats
74
Prevention of FIV
there is an inactivated vaccine for FIV, but efficacy is debatable
75
Treatment of FIV
AZT gives mixed results
in cats with stomatitis, antibiotics + dental hygiene
76
recommendation for HEALTHY FIV positive cats
vaccinate them routinely to prevent infection with other pathogens (prevent as much immunosuppression from FIV as possible)
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FIP/Feline Coronavirus Infection
Feline Infectious peritonitis
SPORADIC but HIGHLY FATAL disease
78
cause of FIP
Feline Enteric coronavirus (FeCoV) from family Coronaviridae
79
what is the virus that is isolated from cats with FIP?
a type of FeCoV that has mutated into FELINE INFECTIOUS PARITONITIS VIRUS (FIPV)
80
How does FIPV differ from FeCoV?
differs genetically but not antigenically
FIPV arises naturally in vivo by mutating and acquiring enhanced ability to replicate in tissue macrophages and circulating macrophages
81
what aged cats is FIP most common in?
young cats <2 years, sometimes very old cats
multi-cat households
82
GeCoV seropositive?
40% of cats in US are seropositive for FeCoV... but FIP is a SPORADIC disease even though FeCoV is common
83
what types of cats does FIP affect?
all cats, even wild cats--> lion, leopard, cheetah, lynx
84
transmission of FIP
ingestion
inhalation is possible, but not common
also by saliva
85
FeCoV is shed by what?
shed in feces of infected cats during active infection
remains in dry feces for a few weeks, serves as source of infectious FeCoV
86
Is FeCoV similar to other coronaviruses?
yes, similar to coronaviruses of pigs, dogs, and humans
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Risk factors of FIP
repeated exposure
large quantities of FeCoV
stress
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incubation period of FeCoV vs incubation of FIP
FeCoV incubation is just a few days
| FIP incubation is > 4 months
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pathogenesis of FIP
- cats infected with FeCoV by ingestion, virus replicates in intestinal epithelial cells, shed in feces
- virus enters blood and infects circulating macrophages
- immune response is induced (IgA, IgG, T cells)
- cat recovers from disease and stops shedding
- minority of cats don't stop shedding upon recovery, remain shedders as a persistent infection in healthy cat
90
How does FIP cause disease
via immune-complexes, antiviral antibodies, and complement
**Cats that have no antibodies to FeCoV DO NOT develop FIP
**Cats with no complement system DO NO develop FIP lesions
91
what % of cats that have been infected with FeCoV develop antibodies to FeCoV and develop FIP?
1-2%
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what is associated with development of FIP?
Stress and environments where cat is exposed to high concentrations of FeCoV
93
describe cellular pathogenesis of FIP
- infection with FeCoV results in seropositive cat with persistent infection (low levels of virus in tissue macrophages)
- when immunosuppressed with Stress, CMI is depressed... allows latent FeCoV to replicate and acquire mutations to replicate even better in macs
- binding of virus to pre-existing Ab cause more macs to get infected when they phagocytose the FeCoV/Ab complex
- infected macs leave blood and enter tissue... virus replication in macs in teh vicinity of blood vessels attracts more Ab, and these Ab fix complement
- C3a and C5a release results in anflammation, which attracts NEUTROPHILS, eventually forms PYOGRANULOMA around the blood vessels
-->causes vasculitis
94
what are the clinical signs seen with FIP?
VASCULITIS
inflammation leads to increased vascular permeability
-protein-rich exudates (in wet form)
95
clinical signs of FeCoV infection
diarrhea or upper respiratory infection
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3 disease forms of FIP
1) effusive form (wet form)
2) Granulomatous form (dry form)
3) mixed form of both 1 and 2
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Effusive form of FIP
development of excessive fluid in chest or abdomen (thoracic effusion of ascites)
anorexia, weight loss, depression, dehydration, and anemia
unresponsive fever
icterus
98
non-effusive/dry form of FIP
granulomatous lesions or pyogranuloma in many areas of body
same general signs (anorexia, weight loss, depression, dehydration, anemia, unresponsive fever)
OCULAR lesions: iritis with color change in iris, keratic precipitates caused by fibrin clot in anterior chamber, retinal hemorrhage, and "cuffing" of retinal vasculature
BEHOVIORAL changes- CNS lesions in 12% of cats with FIP... incoordination, paralysis, seizures
GRANULOMATOUS LESIONS
99
Diagnosis of FIP
History (multicat environment, history of stress in last few months)
clinical pathology (effusive fluid in wet form is clear, straw-colored, clots on standing, and slimy... cellularity is low consisting of macrophages mostly, A:G ratio is 3.5... non-regenerative anemia common, neurtophilia with left shift, hypergammaglobulinemia, increase in acute phase proteins)
Pathology
(if wet form, see rough white deposit on serosal surfaces of abdomen and thorax- exudate is fibrinous... can see pyogranulomas on serosal surface)
(if dry form, see pyogranulomas on various organs... can also see necrotic vasculitis in organs)
Detection of viral antigen (IHC, easily done)
Detection of Virus/Viral nucleic acid
(RT-PCR to detect viral RNA... but RT-PCR also picks up FeCoV that is present in tissues/macrophages of persistently infected cats that do not have FIP)
Detecting of viral specific Ab
(immunofluorescence, monoclonal Ab kit... but problems with these tests)
100
FIP A:G ratio
must be less than 0.45
if >0.8, then it is not FIP
101
what is the only definitive way to make a positive FIP diagnosis
histopathology
102
what is the problem with diagnosing FIP using antibody tests?
presence of circulating Ab to FeCoV does not tell you much, even if it is high... the test cannot distinguish cats infected with FIP from cats infected with FeCoV
"more cats have died of FIP Ab tests than of FIP"
if Ab test comes back negative, you can rule out FIP ONLY if no clinical signs present
advanced cases of FIP can come back Ab negative
103
what has to happen to cause effusion due to FIP
Ab-Ag complex deposited in the vascular bed
104
Vaccine for FIP
Primucell vaccine (attenuated temperature sensitive vaccine)... given IN
-virus vaccine replicates in respiratory tract and does not go systemic, causes good CMI response
105
what is the problem with Primucell vaccine
safe but only partially effective
106
Treatment of FIP
NO TREATMENT
best rpevention is good hygiene and disinfection... can have test and slaughter to reduce FeCoV carrier cats
107
Feline Panleukopenia synonyms
Feline Distemper
Feline Infectious Enteritis
Cat Fever
Cat Plague
108
Feline Panleukopenia characteristics
highly contagious, sometimes fatal viral disease of cats
vomiting, sever dehydration, and neutropenia
109
age most susceptible to panleukopenia
kittens... primarily young unvaccinated kittens (<6months)
110
what causes panleukopenia
a parvovirus (very resistant, can persist for months)
family Parvoviridae (only one serotype is recognized)
111
in natural population, what % is seropositive?
70% of cats
| 75% of unvaccinated cats become seropositive within 1 year of age
112
How susceptible is the panleukopenia virus?
Parvoviridae family (unenveloped)
very resistant, can only be killed by 1:32 bleach or formalin
not killed by iodides, phenol, or alcohol
113
what is panleukopenia virus related to antigenically?
mink enteritis virus and canine parvovirus-2
114
what species can panleukopenia cause disease in?
domestic and wild cats
mink
raccoons
115
how is panleukopenia transmitted?
orally by contact with infected cats or contaminated fomites (fecal-oral)
infected cats can shed virus for 6 weeks after initial infection
116
who is most susceptible to panleukopenia?
all ages susceptible, but mostly seen in unvaccinated young kittens (2-6 months)
117
pathogenesis of panleukopenia
primary site of repliaction is oropharynx
viremia follows, and lymphocytes and fast dividing cells are infected
virus replicates only in fast-dividing cells
118
what cells does panleukopenia virus infect
ONLY fast dividing cells (high mitotic index)
1) lymphocytes in bone marrow, thymus, spleen, LN
2) undifferentiated epithelial cells at the base of crypts
3) myeloid cell precursors- neutrophils
119
what is the result of panleukopenia virus infecting cells
infects myeloid precursors/neutrophils--> SEVERE NEUTROPENIA
infects crypt cells--> necrosis of villi, shortening of villi in jejunum and ileum
120
Can panleukopenia be transmitted transplacentally?
yes!
if fetus infected:
early in gestation- fetal death, reabsorption, infertility
mid gestation- abortion/birth of mummified fetus
late in gestation- cerebellar hypoplasia and optic nerve atrophy
121
What kind of disease is seen with Panleukopenia in kittens vs older cats?
Kittens: acute and lethal infections if kittens have no immune protection
in cats, there is partial protection by Ab, so milder disease
122
what plays a rold in pathogenesis of Panleukopenia?
secondary bacterial infection
123
what type of disease is seen in older cats with panleukopenia?
mild, subclinical or asymptomatic disease unless the cats are immunosuppressed/FIV positive
124
Stages of Panleukopenia disease
Peracute- young kittens
-overwhelming infection... no clinical signs, death within 1 day
Acute disease
- fever, depression, anorexia, vomiting
- EXTREME dehydration
- characteristic posture: hunching over water bowl with head between paws
- 25-90% case fatality
Cerebellar hypoplasia
- seen in kittens born to dams infected late in pregnancy
- incoordination, hypermetria, ataxia
125
Diagnosis of Panleukopenia
History (young cat, anorexia, vomiting, dehydration)
clinical patho
- LEUKOPENIA (<4000 cells/uL)
- neutropenia, sometimes anemia
pathology:
- at necropsy, dehydration with dilated SI (turgid hose-like appearance); edematous LN; petechial hemorrhages
- Histopath: ballooned crypts, shortened villi, IN inclusions in jejunum and ileum
```
Virus isolation (not frequently done because FA faster)
-easily isolated on feline tissue culture cells
```
Detection of viral Ag
-FA test or immunohistochemistry or ELISA
Detection of Virus/Viral Nucleic acid
- can be done by electron microscopy (not done usually)
- PCR
Detection of Ab
-serology
126
Prevention of Panleukopenia
- kittens receive maternal antibodies via colostrum (half-life 8 days)... vaccinate at 9-10 weeks and again in 2 wks
- can give hyperimmune serum prophylactically
- disinfect premises with parvo scrub
- vaccine
127
treatment of panleukopenia
withold food, give fluids and antibiotics
128
what age felines will we give MLV to?
NOT IN YOUNG KITTENS (<3wk) OR PREGNANT QUEENS
| -for these, you will give inactivated vaccine
129
by when will all kittens respond successfully to vaccination for panleukopenia
12 weeks of age (before 12 weeks, 70% of kittens will respond...maternal Ab interfere)
