LEC 15 - Retrovirals I Flashcards
Retroviral Characteristics
Enveloped
diploid
+ sense ssRNA
What are the two components of enveloped glycoproteins?
Surface
Transmembrane
What is the function of the surface glycoproteins?
Bind to the host cell receptors
What is the function of the transmembrane glycoproteins?
Mediates membrane function
What are the three common enzymes present in retrovirals?
Reverse transcriptase
Integrase
Protease
What are the steps to a retrovirus entering a host cell?
Attachment + Fusion
Reverse transcription of ssRNA to DNA
DNA into host cell chromosome
Viral replication + protein synthesis
Assembly of nucleocapsid + insertion of glycoprotein
Budding
FeLV: Envelope proteins
gp70 + p15E
FeLV - Capsid proteins
p27
FeLV - Enzymes
RT
Ingegrase
Protease
What are the four subtypes of FeLV?
A
B
C
T
What subtype of FeLV do cats acquire?
subtype A
How do the other FeLV subtypes form?
Via mutation + recombination events
FeLV Subtype A Characteristics -
Contagious
Mildly pathogenic
Immune suppression
FeLV Subtype B Characteristivs -
Neoplastic
FeLV subtype C characteristics -
Erythroid hypoplasia + Anemia
FeLV subtype T characteristics -
Infect/destroy T cells
Who is most susceptible to a FeLV infection?
Kittens
What is the most common mode of transmission for FeLV?
Saliva
via grooming + feeding + biting
What is the pathogenesis of FeLV?
Virus replicates in the local lymphoid tissue
Spreads via the lymphatics
Goes to bone marrow + epithelial lining in the GI tract
Amplification of the virus occurs
Integration of provirus in RBC’s
Spreads to epithelial + glandular tissue
Shedding
Once again, basic stages of the FeLV virus?
Oral cavity
Lymphatics
Bone marrow/Intestinal lining
Blood
Multi-systemic infection
What does the FeLV virus infect in bone marrow?
Perioperal blood leukocytes
Platlets
What are the two ways that FeLV can lead to tumor development?
Random incorporation of provirus DNA into host genome
– or –
Mutations in virus leading to FeSV
What cancer is most commonly seen when the virus becomes a part of the host genome?
Thymic lymphoma
How does FeSV cause cancer to occur?
Genetic exchange between FeLV and FeSV results in recombinant FeSV becoming ocogenic
What are the four stages of FeLV infections?
Abortive
Regressive
Progressive
Focal
What occurs in the abortive stage of an FeLV infection?
Effective immune response
Local replication then does not progress
No viral antigen or DNA detected
NO VIREMIA
What happens in the regressive stage of an FeLV infection?
Effective immune response
Systemic spread then virus becomes contained
Generally aviremic (no shedding, no disease)
Remains latent - reactivate with decline in immune system
Carriers
What happens in the progressive stage of a FeLV infection?
Ineffective immune response
Persistant viremia
Clinical disease
Fatal
What occurs in the focal stage of a FeLV infection?
Atypical local viral replication
What are the symptoms of FeLV?
Fever + diarrhea + wt loss
Enlarged LN
Myleosuppression
Recurrent secondary infections
Neurological disorders
Cancer
How is FeLV diagnosed?
Symptoms - though not enough on own
CBC with diff
ELISA
What is the ELISA testing for with FeLV?
p27 antigen
What do you see in a CBC diff in a cat with FeLV?
Anemia
Leukopenia
+/- thrombocytopenia
What are the treatment options for FeLV?
Supportive care
Antibiotics for secondary infections
Antiviral agents
Lymphocyte T-cell immunomodulator
What are the two antivirals used to treat FeLV?
Interferon
AZT
What is LTCI?
Purified thymic epithelial protein
Promotes T cell production + activation
FIV - Envelope proteins
gp95 + 36
FIV - Capsid proteins
p24
What are the enzymes present in FIV?
RT
Protease
Who has an increased risk of FIV infection?
Older cats
What is the most common mode of transmission when it comes to FIV?
Saliva
Bite wounds
What happens with FIV + FeLV infections?
Abortion
What is the target cell in FIV infections?
CD4+ T Lymphocytes
What does FIV bind to on lymphocytes?
CD134 + CXCR4
What is important about macrophage infection of FIV?
Important viral reservior
What are the three stages of an FIV infection?
Acute
Asymptomatic
Terminal
What symptoms are seen in the acute phase of the FIV infection?
Flu-like symptoms
Fever
Malaise
Lymphadenopathy
GI disorders
Stomatitis
What symptoms are seen in the asymptomatic phase of an FIV infection?
Carrier status
Recurrent infections
Neoplasms
What occurs in the terminal phase of a FIV infection?
Generalized immunosuppression
Leading to many clinical symptoms
What are FIV symtpoms associated with?
Decrease immune status of the cat
What does progonosis depend on in a cat with an FIV infection?
Clinical symptoms
Stage of disease
What is used to diagnose FIV?
Symptoms
CBC with Diff
ELISA + IFA
What is seen on a CBC diff in a cat with a FIV infection?
Lymphopenia in ill cats
Anemia in about 1/3 of cats infected
What is the target of a FIV ELISA test?
p24 antigen antibodies
What cell types are targeted by EIAV?
Monocytes
Macrophages
EIAV - Glycoproteins
gp90
gp45
EIAV - Capsid
p26
What enzymes are present in the EIAV?
RT
Inegrase
Protease
How does EIAV target monocytes and macrophages?
ELR1 receptor
(TNF-family receptor)
What does EIAV cause? (disease names)
Swamp fever
Horse malaria
Equine infectious anemia
How is EIAV spread?
Blood-feeding insects
Horsefly
Deer Fly
Stable Fly
What is clinical disease corrleated to in EIAV?
Viral load
When are viral loads highest in EIAV infections?
Febrile episodes
What is the cause of the clincal symptoms seen? (what is happening at the cellular levels)
Monocytes + macrophages attacked
result in pro-inflammatory cytokines
What three things happen at the cellular level with an EIAV infection?
Inflammation + suppression of platelet production = thrombocytopenia
Ab’s bind to platelets leading to destrcution = splenomegaly and hepatomegaly
EIAV absorb onto RBC leading to phagocytosis = type II reaction
What is the incubation period of EIAV?
2 to 4 weeks
What is clinical disease associated with in EIAV?
Active viral replication
How long does it take a horse to die from EIAV with acute symptoms?
3 to 14 days
What is seen in EIAV chronic disease?
Surive inital effects and then can develop recurring clinical disease with the same symptoms
Highly vairable
What are the characteristics of EIAV inapparent carriers?
No overt clinical disease
Reserviors for virus
Can show symptoms with severe stress
How is EIAV diagnosed?
COggins test with is an AGID
What does the Coggins test look for?
Antibodies to p26 antigens
How should all animals infected with EIAV be handled?
Isolated