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Microbiology 2 > Lecture 14: retroviruses > Flashcards

Lecture 14: retroviruses Flashcards

1
Q

Are retroviruses enveloped or non-enveloped, + sense ssRNA or - sense ssRNA

A

enveloped, +sense ssRNA

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2
Q

what are the 3 major genes that encode for general structure of retroviruses

A
  1. Env gene
  2. Gag gene
  3. Pol gene
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3
Q

what does env gene do

A

envelope glycoprotein
Encodes for
1. Surface glycoproteins- bind to host cell receptor
2. Transmembrane glycoproteins: mediate membrane fusion

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4
Q

what does gag gene do

A

encodes for
1. Nucleocapsid
2. Capsid
3. Matrix

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5
Q

what does pol gene do

A

enzymes
Encode for
1. Reverse transcriptase: RNA—> RNA
2. Integrase: integrate pro viral DNA into host genome
3. Protease: cleave polypeptide into functional proteins

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6
Q

what is retrovirus life cycle

A
  1. Attachment of envelope glycoproteins to host cell receptor
  2. Fusion
  3. Reverse transcription of ssRNA to DNA
  4. Integration of pro viral DNA into host cell chromosome
  5. Viral replication and protein synthesis
  6. Assembly of nucleocapsid and insert glycoproteins into host membrane
  7. Release of virions by budding from plasma membrane
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7
Q

what is main target of retroviruses

A

immune cells

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8
Q

what are the 3 ways retroviruses can result in cancer

A
  1. Capture and transfer of a host cell proto-oncogene
  2. Insertional mutagenesis
  3. Encoding of proteins that are directly oncogenic to infected cells
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9
Q

how does capture and transfer of host cell proto-oncogene work

A
  1. Incorporates host proto-oncogene into viral genome forming viral oncogene
  2. Infection of another host cell results in transformation
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10
Q

how does insertional mutagenesis work

A
  1. Pro viral insertion near host proto-oncogene may disrupt regulation= conversion of host proto-oncogene to oncogene
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11
Q

What is the important structure in FeLV that we detect antigen for in flow by assay

A

p27 capsid protein

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12
Q

what viral subtype of FeLV is only transmitted between animals

A

FeLV-A

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13
Q

how do other subtypes of FeLV arise

A

mutations and recombination events

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14
Q

FeLV-T arises from mutations in FeLV-A and causes what

A

infects and destroys T cells, leading to lymphoid depletion and immunodeficiency

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15
Q

what is most common mode of transmission for FeLV

A

saliva, grooming, feeding, bites

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16
Q

what are some signs of FeLv

A

Fever, diarrhea, weight loss, anorexia, pale gums, poor coat condition, enlarged LN, leukopenia, anemia, recurrent secondary infections, neurlogical

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17
Q

what cancers are most commonly associated with FeLV

A

lymphomas/leukemias

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18
Q

what is pathogenesis of FeLV

A
  1. Virus replicates in local lymphoid tissue, often oropharynx
  2. Virus infected WBC’s enter blood= primary viremia (bone marrow)
  3. Secondary viremia leading to infection of endothelial cells that can allow for viral replication and shedding
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19
Q

what are the 3 outcomes of FeLv infection

A
  1. Abortive infection
  2. Regressive infection
  3. Progressive infection
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20
Q

what happens in abortive infection of FeLV

A
  1. Effective immune response
  2. Elimination of virus
21
Q

what happens in regressive infection of FeLV

A
  1. Effective immune response- virus contained after systemic spread
  2. Generally aviremic
  3. Remains latent can reactivate if immune system declines
22
Q

what happens in progressive infection with FeLV

A
  1. Ineffective immune response
  2. Viral replication and viral spread- persistent viremia
  3. Clinical disease- often fatal
23
Q

t of f: most cats infected with FeLV will eventually develop a progressive infection

24
Q

what are some FeLV associated diseases

A
  1. Cancers
  2. Myelosuppression
  3. Secondary infections
  4. Other disorders
25
Q

cat dx with FeLV based on signs and IHC. Findings also consistent with lymphoma- based on CD79a IHC is it likely B or T cell lymphoma

A

B cell lymphoma- CD79a part of B cell receptor complex

26
Q

what are the two ways FeLV can lead to development of tumors

A
  1. Insertion of FeLv genome near proto-oncogene or causing disruption of tumor suppressor gene
  2. Recombination of FeLV with cellular proto-oncogenes
27
Q

what tumor is commonly associated with insertion of FeLV genome near proto-oncogene or causing disruption of tumor suppressor gene

28
Q

what cancer is assocaited with recombination of FeLV with cellular proto-oncogenes

A

Results in feline sarcoma virus associated with fibrosarcomas

29
Q

What are some CBC signs of FeLv

A

anemia, leukopenia, thrombocytopenia

30
Q

how do you dx FeLV

A
  1. ELISA and IFA tests- lateral flow assay to detect FeLV p27 antigen
  2. RT-PCR to detect viral RNA, PCR to detect proverbial DNA
31
Q

which lane positive for FeLv

32
Q

what are the lab results of abortive FeLv infection

A

all Ag/PCR tests negative, only indicated of FeLv infection is presence of antibodies

33
Q

what are lab results of regressive FeLv

A

variable Ag/PCR test results

34
Q

what are lab results of progressive FeLV infection

A

all Ag/PCR tests are positive

35
Q

what is tx for FeLV

A

supportive care, minimize stress, antimicrobials for secondary infection

36
Q

how do you prevent FeLV

A

Minimize exposure, vaccinate

37
Q

what FIV structure are antigen and antibody tests looking for

A

p24 cap side and p15 matrix proteins

38
Q

what is the most common mode of transmission of FIV

A

saliva (bite wound)

39
Q

what are some signs of FIV

A

anything that decreases immune status

40
Q

what is FIV pathogenesis

A
  1. Infects CD4+ T lymphocytes resulting in destruction
  2. Virus binds CD134 and CXCR4 expressed by activated and memory CD4+ T lymphocytes
  3. Progressive immune dysfunction
41
Q

what are some signs of primary/acute phase FIV

A

fever, malaise, lymphadenopathy, GI disorders, stomatitis

42
Q

what are some signs of subclinical (asymptomatic phase) of FIV

A

cat are carriers, some recurrent infections, neoplasm

43
Q

t or f: most cats with FIV progress past subclinical phase to clinical/terminal phase

44
Q

what are some signs of clinical/terminal phase FIV

A

various signs due to generalized immunosuppression

45
Q

what does CBC of FIV show

A

lymphopenia, anemia

46
Q

How do you dx FIV

A

ELISA and IFA- detect anti-p15 antibodies and/or P24 antigens

47
Q

what lane shows results for FIV

48
Q

what is tx for FIV

A

supportive care, antimicrobials for secondary infections

49
Q

how do you prevent FIV

A
  1. Minimize exposure
  2. Quarantine/isolate infected cats

Microbiology 2 (24 decks)

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