Retroviridae

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Questions and Answers

What type of genome do retroviruses have?

Single-stranded negative-sense RNA
Single-stranded positive-sense RNA (correct)
Double-stranded DNA
Circular RNA

Retroviruses are non-enveloped viruses formed by budding from the cell membrane

False (B)

Which enzyme allows retroviruses to integrate into the host genome?

Reverse transcriptase
DNA polymerase
Integrase (correct)
RNA polymerase

When the retrovirus has integrated the host genome, it’s not considered a virus yet. It’s still a provirus

True (A) Signup and view all the answers

How can retroviruses alter the host genome?

By inserting their genome near host genes, which may activate or inactivate them (B) Signup and view all the answers

What is the morphology of a retrovirus?

Spherical, enveloped (C) Signup and view all the answers

What is found inside the nucleocapsid of a retrovirus?

Viral RNA, reverse transcriptase, integrase, and protease (C) Signup and view all the answers

What are the three enzymatic functions of reverse transcriptase?

RNA-dependent DNA polymerase, DNA-dependent DNA polymerase, and RNase H (B) Signup and view all the answers

Why are retroviruses easily inactivated by detergents and heat?

Because they have a lipid envelope (C) Signup and view all the answers

Which of the following is resistant to ultraviolet or X-rays?

Virions of retroviruses (A) Signup and view all the answers

What is the function of the gag gene in retroviruses?

Encodes viral core proteins such as capsid and matrix (B) Signup and view all the answers

Each RNA genome is between & kb

7 and 11 Signup and view all the answers

The virion of retroviruses has at least 3-4 important genes

True (A) Signup and view all the answers

The pol gene encodes which enzyme(s)?

Reverse transcriptase and integrase (B) Signup and view all the answers

Which retroviral gene is responsible for encoding envelope proteins?

Env (C) Signup and view all the answers

What is the function of the pro gene?

Encodes protease (A) Signup and view all the answers

Which of the following is a characteristic of alpharetroviruses?

They contain gag, pol, env and pro genes (C) Signup and view all the answers

What is an example of alpha retrovirus?

Avian leukosis sarcoma virus (C) Signup and view all the answers

Alpharetrovirus is referred to as simple retroviruses

True (A) Signup and view all the answers

Alpharetrovirus is exclusively exogenous viruses of chickens

False (B) Signup and view all the answers

What is the difference between endogenous and exogenous retroviruses?

Endogenous retroviruses are included in the host genome and passed down generations, while exogenous retroviruses are transmitted horizontally (B) Signup and view all the answers

Which retrovirus group has the largest number of members?

Gammaretrovirus (B) Signup and view all the answers

Gammaretroviruses are also simple retroviruses

True (A) Signup and view all the answers

Which of the following is an example of a gammaretrovirus?

Avian reticuloendotheliosis virus (B) Signup and view all the answers

Which of the following is another example of a gammaretrovirus?

All the above (D) Signup and view all the answers

Gammaretrovirues contain both endogenous and exogenous retroviruses of mammals and _________

Reptiles Signup and view all the answers

What is an example of a deltaretrovirus?

Human T-lymphotropic virus (HTLV) (B) Signup and view all the answers

Deltaretrovirues are considered complex retroviruses

True (A) Signup and view all the answers

The other famous example of Deltaretrovirus is bovine leukemia virus

True (A) Signup and view all the answers

What is the main characteristic of lentiviruses?

They cause slow, progressive diseases (A) Signup and view all the answers

Which of the following is an example of a lentivirus?

Feline immunodeficiency virus (FIV) (A), Humann immunodeficiency virus (HIV) (B) Signup and view all the answers

Which lentivirus affects goats and causes arthritis and encephalitis?

Caprine arthritis-encephalitis virus (B) Signup and view all the answers

Which of the following Genuses is NOT a complex retrovirus?

Gammaretroviruses (D) Signup and view all the answers

Why are lentiviruses considered “slow”?

It’s because they have a long incubation period that slowly develops into the disease! Signup and view all the answers

Which of the following is the correct sequence of retrovirus replication?

Receptor binding → Internalization → Reverse transcription (of RNA to linear dsDNA) → Integration (formation of provirus) (C) Signup and view all the answers

What is the role of reverse transcription in retroviral replication?

Converts RNA genome into linear dsDNA (B) Signup and view all the answers

Which step occurs after the integration of viral DNA into the host genome?

Transcription of provirus to viral RNA (A) Signup and view all the answers

How do retroviruses contribute to oncogenesis?

By inserting viral oncogenes (v-onc) into the host genome (B) Signup and view all the answers

Which statement about viral oncogenes (v-onc) is true?

They are acquired from host cellular proto-oncogenes (c-onc) (A) Signup and view all the answers

Which of the following best describes acute transformation caused by retroviruses?

It occurs when viral oncogenes (v-onc) directly drive rapid tumor formation. (A) Signup and view all the answers

How does chronic transformation differ from acute transformation in retroviral oncogenesis?

Chronic transformation results from proviral insertion/mutation through random integration into the genome of the host near proto-oncogenes, leading to slow oncogenesis. (B) Signup and view all the answers

Such a viral oncogene may lead to transformation of infected cells by acting as a _______, _, or ______

Such a viral oncogene may lead to transformation of infected cells by acting as a growth factor, receptor, intracellular signal transducer or intranuclear transcription factor Signup and view all the answers

Which of the following genes in FeLV codes for the reverse transcriptase enzyme?

pol (C) Signup and view all the answers

What is the function of the env gene in FeLV?

Codes for glycoproteins gp70 (SU) and p15E (TM) (C) Signup and view all the answers

Which FeLV subtype is ubiquitous the result of mutations in the env gene of FeLV?

FeLV C (C) Signup and view all the answers

What is the function of the gag gene in FelV?

Codes for the structural proteins of the virus including p27 (C) Signup and view all the answers

Which FeLV subtype is ubiquitous and involved in every infection?

FeLV A (A) Signup and view all the answers

What are the risk factors for infection with FELV?

Young age, high population density, and poor hygiene Signup and view all the answers

How is FeLV primarily transmitted between cats?

Mutual grooming and bites (B) Signup and view all the answers

How is the virus shed from the infected cat?

It’s shed through saliva, nasal secretions, feces and milk Signup and view all the answers

In viremic queens, what does pregnancy usually result in?

Embryonic death, stillbirth or in viremic kittens Signup and view all the answers

Which viral protein is the main determinant of FeLV pathogenicity?

SU (surface glycoprotein) (C) Signup and view all the answers

How does FeLV primarily spread within the host after infection through the oral or pharyngeal associated tissue?

Through infected monocytes and lymphocytes (B) Signup and view all the answers

FeLV has tropism to lymphoid tissue

True (A) Signup and view all the answers

Which receptors does FeLV use to attack T lymphocytes?

Pit1 and FeLIX (B) Signup and view all the answers

The reduced number of CD4+ Tcells induces ___________

Low or no cellular immunity Signup and view all the answers

What is the main consequence of FeLV-induced immunosuppression?

Predisposition to fungal infections and peritonitis (B), Predisposition to infections like mycoplasmosis and toxoplasmosis (A) Signup and view all the answers

How does the viral protein p15E contribute to FeLV pathogenesis?

It blocks T cell reactivity to IL-1 and IL-12 (B) Signup and view all the answers

What hematologic effect does FeLV-induced p15E protein have?

Blocks production of hematopoietic cells, leading to anemia (C) Signup and view all the answers

Why do FeLV-infected cats develop glomerulonephritis?

Deposition of antigen-antibody (Ab-Ag) complexes (C) Signup and view all the answers

The deposition of Ab-Ag complexes are a type 2 hypersensitivity

False (B) Signup and view all the answers

Which type of anemia is most commonly associated with FeLV?

Non-regenerative anemia caused by myelosuppression (C) Signup and view all the answers

Which of the following is a possible consequence of FeLV-related immune suppression?

Lymphoma and leukemia (B) Signup and view all the answers

Which diagnostic test for FeLV has approximately 90% sensitivity?

p27 ELISA (C) Signup and view all the answers

Which FeLV diagnostic method was the first to detect viraemic cats in field conditions?

Immunofluorescence assay (IFA) (B) Signup and view all the answers

Which FeLV diagnostic method is considered gold standard for ultimate criterion for FeLV infection?

Virus isolation in cell culture (A) Signup and view all the answers

Which molecular diagnostic test is used to detect FeLV provirus?

Reverse transcriptase PCR (B) Signup and view all the answers

Why is serology not widely used for FeLV diagnosis?

Many cats develop antibodies to their endogenous FeLV, making interpretation difficult (A) Signup and view all the answers

Which of the following is a criterion for testing a cat for FeLV infection?

Cats that are sick (B), Cats with known recent exposure to an FeLV-infected cat (C), Cats living in a household with other cats infected with FELV (D) Signup and view all the answers

Which of the following is TRUE regarding FeLV treatment?

The virus doesn’t survive for long periods outside the host , so it’s easily destroyed by disinfectants, soap, heat and drying (A) Signup and view all the answers

Flashcards

Retrovirus genome type?

Single-stranded positive-sense RNA.

Retroviruses: enveloped or non-enveloped?

False. Retroviruses are enveloped viruses that acquire their envelope by budding from the cell membrane.