Retroviridae-Birnaviridae (exam 2) Flashcards
T/F: Retroviridae may exist as a stable component in the host genome
True
T/F: Reverse transcriptase is an RNA-dependent DNA polymerase
True
What is essential for retroviruses to replicate?
reverse transcriptase
What are the 2 subfamilies within retroviridae?
Orthoretrovirinae and spumaretrovirinae
How do retroviruses acquire their envelope?
By budding from the cell membrane of the cell they replicate from.
T/F: Retroviruses have a diploid genome with 2 copies of single stranded, negative sense RNA.
False. It is positive sense RNA (everything else is true).
How do retroviruses integrate into the host genome?
by using an enzyme called integrase.
What is found within the nucleocapsid of retroviruses?
2 single strands of viral RNA, reverse transcriptase, integrase, and protease.
T/F: retroviridae virions are not resistant to UV or x-rays
False.
How are retroviridae virions inactivated?
lipid solvents or detergents and by heating.
What does the gag gene encode?
capsid, nucleocapsid, and matrix.
What does the pol gene encode?
reverse transcriptase and integrase
Alpharetroviruses are within which family and subfamily?
Family: retroviridae Subfamily: orthoretrovirinae.
What two diseases represent alpharetroviruses?
avian leukosis and sarcoma virus (ALSV)
How are exogenous retroviruses transmitted?
horizontally.
What are endogenous retroviruses and how are they transmitted?
Viruses included in the genome of most, if not all, animals. Vertically as part of the host genome (passed on from generation to generation).
Who are the members of the alpharetrovirus genus?
avian leucosis virus, avian sarcoma virus, avian myeloblastosis virus, Rous sarcoma virus.
What virus is representative of betaretroviruses?
Mouse mammary tumor virus.
What does the sag gene in MMTV code for?
superantigen.
Feline leukemia virus belongs to what genus?
Gammaretroviruses.
T/F: gammaretroviruses affect mammals and reptiles.
True
What is special about the deltaretroviruses genome?
they contain regulatory genes rex and tax that are expressed from an alternatively spliced mRNA.
T/F: deltaretroviruses are endogenous and exogenous.
False. Only exogenous.
What is the prototype of epsilonretroviruses?
Walleye dermal sarcoma virus.
T/F: epsilonretroviruses are the only exogenous retroviruses found in fish and reptiles.
False. Only endogenous retroviruses in fish and reptiles.
HIV, caprine arthritis-encephalitis virus and meadi-visna virus are important members of what genus?
Lentiviruses
What is the purpose of the nef gene and what genus is it found in?
it encodes for the nef protein which is essential for replication in target hosts but not in vitro. It can also downregulate the expression of CD4 molecule and alter the activation status of target cells. It is found in lentiviruses.
T/F: Spumaviruses are zoonotic.
True.
What viruses (genus) are considered complex viruses?
Spumaviruses, lentiviruses, epsilonretroviruses, and deltaretroviruses.
What virus exemplifies spumaviruses?
human foamy virus
What is necessary for retroviruses to enter a cell?
interaction between a cell surface molecule (receptor) and the envelope proteins on the virion surface.
What receptor is present for cat, dog, and primate gammaretroviruses?
GLVR1
What receptors are present for FeLV gammartroviruses?
FeLIX and Pit
What is the core receptor for lentiviruses?
CD4 found on T helper cells.
What are some outcomes of retroviruses?
acute disease due to cell death, latent infection, chronic infection.
What do retroviruses that lead to acute transformations contain?
viral oncogenes
p27 in FeLV is encoded by what gene and what is it’s purpose?
encoded by the gag gene and it is used in ELISA tests.
Do we have to worry about FeLV transmission via fomites? Why or why not?
No, because the virus is readily destroyed by disinfectants, soap, heating and drying.
How is FeLV shed?
in saliva, nasal secretions, feces, and milk.
T/F: FeLV can be transmitted through mutual grooming
True.
T/F: FeLV can be transmitted via individual mammary glands.
True
What is the main determinant of pathogenicity in FeLV?
SU protein.
Tropism to lymphoid tissue is seen with FeLV. What can this lead to?
Immunosuppression, which can lead to secondary infection.
T/F: there is low or no humoral immunity with FeLV.
False. There is low or no cellular immunity.
What role does p15e play in FeLV?
blocks T cell reactivity to IL-1 and IL-12 and blocks production of hematopoietic cells, which leads to anemia.
What immunoglobulin levels are normal in an FeLV infection?
IgG
What are some clinical signs seen with FIV?
dehydration, stomatitis, fever, along with bite wounds and other changes in the oral cavity.
T/F: FeLV can cause lymphoma and leukemia in chronic infections.
True.
What is the diagnostic of choice for FeLV?
p27 ELISA.
T/F: FeLV vaccine prevents infection and provides complete protection.
False.
What interleukin’s production is reduced by FIV? Which is increased?
IL-2 is decreased, IL-10 is increased (leading to immunosuppression).
How does FIV deepen immunosuppression?
by activating CD4+/CD25+ Treg
Who discovered FIV?
Janet Yamamoto and Niels Pederson.
Who is more likely to get FIV, male or female felines?
Males.
How is FIV spread?
Deep bite wounds and scratches. Saliva must enter bloodstream.
T/F: FIV cannot be transmitted in utero or via mother’s milk.
False. It can be, although it is rare.
FIV’s oral clinical signs resemble what other virus?
Calicivirus.
Does FIV cause abortions?
Yes, but indirectly. It is the high fever which is thought to be the reason for abortions.
What is the most common and reliable method of diagnosis for FIV?
ELISA.
T/F: cats affected with FIV cannot live long, happy lives.
False. They can and should not be condemned.
Retroviruses that cause disease in birds belong to what groups?
Alpharetroviruses and gammaretroviruses.
What is the most common form of avian leukosis caused by retroviruses?
Lymphoid leukosis.
What can lead to tumor formation in avian retroviruses?
overexpression of the c-myc oncogene.
What is “thick leg syndrome” and what is it caused by?
osteoporosis, caused by a replication defective avian retrovirus.
What is one example of cellular transformation of oncogenic viruses? What organs may you see swollen due to this?
erythroblastosis, liver and kidneys may be swollen.
Why is equine infectious anemia virus (swamp fever) typically not reported?
Because animals are usually asymptomatic.
How is swamp fever transmitted?
mainly by biting insects.
What is special about the fly’s ability of transmitting equine infectious anemia virus?
It will not transmit the virus if it is able to feed uninterrupted.
Where does swamp fever replicate and how does it get there?
In macrophages. It infects monocytes initially and begins to replicate once monocytes become macrophages.
What are the clinical signs you look for in equine infectious anemia virus?
petechial hemorrhages and edema. Asymptomatic carriers have a decrease in performance.
What is the test of choice for swamp fever?
Coggin’s test, AKA agar gel immunodiffusion.
Paramyxoviruses belong to what order?
Mononegavirales
What genus of paramyxoviruses are of concern?
Henipavirus
What family does Newcastle disease now belong to?
Avulavirus.
What is bovine respiratory syncytial virus used for?
as a model to study the human virus.
T/F: Paramyxoviruses virions are pleomorphic
True
T/F: the paramyxovirus genome is linear, single stranded, negative sense RNA.
True
What are the attachment proteins in paramyxovirus?
HN or G.
How do the antibodies directed against glycoproteins HN, H, or G protect against paramycovirus infection?
They are neutralizing antibodies.
Where do paramyxoviruses replicate?
Cytoplasm of infected cells.
What is the F protein responsible for?
F protein mediates fusion of the viral envelope lipid membrane with the target cell membrane.
What is a distinctive feature of paramyxoviruses that express the H or HN protein?
Hemoadsorption.
T/F: Inclusion bodies are always produced when paramyxoviruses replicate.
True
New Castle Disease is in what genus? What serotype has it been designated?
Avulavirus APMV-1
Does New Castle disease affect turkeys?
Yes, but infection is usually mild.
Who can transmit New Castle disease subclinically?
Wild birds and waterfowl
Is New Castle disease zoonotic?
Yes! Causes mild disease characterized by excessive lacrimation, oedema of the eyelids, conjunctivitis, and sub-conjunctival hemorrhage.
How is New Castle disease transmitted?
Direct contact with secretions of infected birds (ingestion or inhalation), and via fomites.
Where are lentogenic strains of NDV found?
Worldwide.
Can you diagnose NDV by looking at clinical signs alone/
No.
What do you typically see with lentogenic strains of NDV?
subclinical disease with mild respiratory symptoms.
In which strains is mortality low for NDV?
Mesogenic and lentogenic
Which strain of New Castle Disease cause greenish or white diarrhea, dyspnoea, inflammation of the head and neck, and cyanotic discoloration?
Velogenic Strain
Which strain of NDV has high mortality?
Velogenic strain
How do you diagnose velogenic strains of NDV?
tentative dx determined by examining several birds. Final DX determined by virus isolation.
T/F: Velogenic and Mesogenic strains cause significant gross lesions.
False. Only Velogenic strains do.
Is NDV a reportable disease?
Yes.
What is the best way to dx NDV?
Isolating the virus.
Is there a vaccine available for NDV?
Yes, there are 2 groups of vaccines: lentogenic and mesogenic vaccines.
Is there treatment or paramyxovirus 1?
No.
Is the Nipah virus zoonotic?
Yes, it is an emerging zoonosis causing severe disease in animals AND humans.
What does the Nipah virus typically cause?
encephalitis and respiratory illness.
What genus does Nipah virus belong to?
Henipavirus.
What does Nipah virus cause in pigs? And in humans?
severe, respiratory disease in pigs and rapidly progressive encephalitis in humans.
What animals carry the Nipah virus and where is it found?
Flying foxes (aka fruit bats). They carry it in their urine and potentially saliva.
Is Nipah virus stable in the environment? What is it susceptible to?
Yes, especially in bat urine and contaminate fruit juice. Susceptible to common soaps and disinfectants.
What clinical signs are typically seen in young swine 1-6 months old with Nipah virus?
acute fever, labored breathing, nasal discharge, and loud, nonproductive cough. Neurologic signs can be seen.
What clinical signs are typically seen in swine greater than 6 months with Nipah virus?
acute fever, marked neurologic signs, respiratory signs, and first trimester abortions.
This virus is in the genus Henipavirus and is classified as a BSL4 agent.
Nipah virus
What are 3 ways to ID Nipah virus? What is the preferred method of ID?
Virus isolation and characterisation, virus neutralisation, and immunohistochemistry.
What do you do if a pig tests positive for Nipah virus?
Cull them.
T/F: Nipah virus is a biological weapon and can be used in bioterrorism.
True.
What genus does the canine distemper virus belong to?
Morbilivirus.
Which lineage of canine distemper virus is circulating in dogs in north america?
None.
Which lineage of canine distemper virus is circulating in raccoons in the USA?
America 1
What percentage of distemper infections are subclinical or mild?
50%
What is a key sign of distemper?
nasal discharge that starts as serous and quickly becomes mucopurulent.
What is typically seen in dogs with canine distemper that have CNS signs?
seizures, paraparesis, tetraparesis, and hyperkeratosis on footpads and nose.
T/F: canine distemper virus is stable in the environment.
False.
Who is most susceptible to canine distemper?
young dogs, 4-6 months of age.
In what cells does the canine distemper virus replicate?
Upper respiratory tract macrophages.
T/F: Canine distemper virus infects all cells expressing CD150
True
What is the best way to diagnose canine distemper?
virus isolation, by adding the virus to lymphocytes. If the cells become shiny, you know the virus is present.
When do you vaccinate puppies against canine distemper?
Only after maternal antibodies have gone down.
When was the high pathogenicity avian influenza virus isolated?
in 1961
What disease do orthomyxoviruses cause?
Influenza
How are influenza viruses classified?
based on the type of hemagglutinin and neuraminidase
Which strain of influenza was the first high pathogenicity avian influenza virus of the H5 subtype?
H5N1
T/F: orthomyxoviruses are pleomorphic with a segmented genome
True.
Which influenza genus lacks neuraminidase?
Influenza C.
What are the functions of the surface HA?
receptor binding, membrane fusion, and receptor cleavage.
What protein is important in the diagnosis of the influenza virus?
M1- matrix protein.
What causes influenza viruses to be sensitive to heat, acidic pH and lipid solvents?
their lipid envelope.
Are influenza viruses negative or positive sense?
Negative sense.
Where in the cell do orthomyxoviruses replicate?
In the nucleus.
What orthomyxovirus is transmitted by ticks and replicates both in the tick and in mammals?
Thogotoviruses.
Changes in antigenic setup due to point mutations is known as what?
Genetic drift.
Changes in antigenic set up due to reassortment of genetic segments is known as what?
Genetic shift
What is the most important viral respiratory disease of horses?
Equine influenza viruses
T/F: equine influenza virus is zoonotic.
False.
T/F: It is the immune response that makes equine influenza virus worse on the horse, the initial damage of the virus is actually minimal.
True.
When is equine influenza likely to end up as bronchopneumonia or chronic respiratory disease?
When the virus is not taken care of rapidly and secondary infections occur.
What is the normal temperature of a newborn horse? Adult horse?
99.5-102.1 (37.5-38.9) and 99.1-101 (37.2-38.3)
T/F: equine influenza can lead to abortion.
True. Prolonged fever due to the virus can cause abortion.
How long do animals remain infectious with equine influenza virus?
5 days after clinical signs have disappeared.
T/F: equids are not the only source of equine influenza viruses.
False. They are the only source.
What is the diagnostic test of choice for equine influenza?
RT-PCR (it is also quick)
Is there a vaccine for equine influenza virus?
Yes, there are inactivated vaccines or live vectored vaccines.
Who was the person that isolated swine influenza?
Richard Shope
Is swine influenza zoonotic?
yes.
T/F: pigs can become infected with avian and human strains of influenza viruses.
True. This causes them to be known as “mixing vessels”
How is swine influenza transmitted?
through aerosols.
Where does swine influenza replicate?
In the upper respiratory tract.
T/F: swine influenza has a long incubation period.
False.
T/F: you have to cull all pigs diagnosed with swine influenza, despite their ability to recover.
True
What is the preferred method to diagnose swine influenza?
hemagglutination inhibition test. Can indicate whether or not there is an active infection.
Why are swine influenza viruses economically important?
because of the losses caused due to culling the piggies.
Are there vaccines available for swine influenza?
Yes, but they do not provide cross-protection against new subtypes.
What virus is known as the “fowl plague”?
Avian influenza virus.
T/F: you have to cull birds affected with avian influenza, thus bringing about economic losses.
True.
This virus is notifiable, affects poultry, and is divided into highly pathogenic and low pathogenicity.
Avian influenza virus
Where does the avian influenza virus replicate in birds?
In the intestinal and respiratory tracts, which causes very high viremia.
Which subtype of avian influenza may kill birds with no clinical signs?
Highly pathogenic avian influenza
What is a typical clinical sign of both avian influenza viruses?
cessation/decrease in egg production.
How is avian influenza diagnosed?
by RT-PCR to detect the matrix protein gene.
How do you know which subtype of avian influenza is present?
Analyzing the H gene (if H5 or H7) to determine the cleavage site. If the cleavage site is arginine, it is LPAI, if it is basic amino acids it is HPAI.
Is there a vaccine available to control HPAI?
No.
T/F: there is limited person to person spread of swine influenza
True.
T/F: all flaviviruses are transmitted by vectors.
True.
Who recognized flavivirus as a filterable agent?
Walter Reed and James Carrol
Are flaviviruses positie or negative sense? Are they enveloped?
positive, yes.
T/F: flaviviruses have an infectious RNA.
True.
Where does flavivirus replication take place?
In the cytoplasm.
What are flaviviruses susceptible to?
heat, common disinfectants, and lipid solvents.
Which is the only flavivirus resistant to heat?
Classical swine fever
Which West Nile Virus lineage is seen in North and South America and is also enzootic in Australia?
WNV-1