Virus Lecture Exam Flashcards
What are viruses considered?
Obligate intracellular parasites
What are possible things viruses can have?
DNA or RNA
Protein Coat or no Protein Coat
Envelope or No Envelope
Viruses are able to pass through a filter as small as…?
0.2 um filters so find a smaller one to exclude viruses bigger than 0.2um
What are some things viruses lack?
Cytoplasm, cell membranes, ribosomes, other organelles, machinery that produces energy or biosynthetic things for an independent life
What are two kinds of things that are the same size or smaller than a virus?
Viroids and prions
What part of the virus directs the synthesis of viral components by hijacking cellular systems in the host?
viral genome
Define virions
A single infectious virus particle
What are the steps of the virus’ infectious cycle?
- Attachment
- Penetration
- Uncoating
- Replication
- Maturation
- Release - Lysis (ideal) and apoptosis (less than ideal)
What organization is responsible for viral nomenclature?
International Committe on Taxonomy of Viruses (ICTV)
True or false, ICTV, internaltional committee on taxonomy of viruses classify viruses past the species level.
False they do not. They don’t recognize subspecies level of viruses
In viral taxonomy, The order of viruses would have what suffix?
-virales
In viral taxonomy, the family level of viruses would have what suffixes?
-viridae
In viral taxonomy, the subfamily level of viruses would have what suffixes?
-virinae
In viral taxonomy, the genus level of viruses would have what suffixes?
-virus
Describe the baltimore classification
A scheme for classifying viruses based on the type of genome and its replication strategy. The characteristics are viral genome ‘s nucleic acid ( DNA or RNA ), strandedness (single-stranded or double-stranded), Sense, and method of replication determine its class.
What are the 7 groups of baltimore classification?
I: dsDNA viruses (e.g. Adenoviruses, Herpesviruses, Poxviruses)
II: ssDNA viruses (+)sense DNA (e.g. Parvoviruses)
III: dsRNA viruses (e.g. Reoviruses)
IV: (+)ssRNA viruses (+)sense RNA (e.g. Picornaviruses, Togaviruses)
V: (−)ssRNA viruses (−)sense RNA (e.g. Orthomyxoviruses, Rhabdoviruses)
VI: ssRNA-RT viruses (+)sense RNA with DNA intermediate in life-cycle (e.g. Retroviruses)
VII: dsDNA-RT viruses (e.g. Hepadnaviruses)
What are examples of the first group of the baltimore classification?
Group I, double strand DNA viruses. Examples are Adenoviruses, Herpesviruses, Poxviruses
What are examples of the second group of the baltimore classification?
Goup II, single strand DNA viruses that are positive sense. One example is Parvoviruses
What are examples of the third group of the baltimore classification?
Group III, double strand RNA viruses. An example is Reoviruses
What are examples of the fourth group of the baltimore classification?
Group IV, (+) single strand RNA viruses, Positve sense RNA. Examples are picornaviruses and togaviruses
What are examples of the fifth group of the baltimore classification?
Group V, (-) single strand RNA viruses, negative sense RNA. Examples are orthomyxoviruses and rhabdoviruses
What are examples of the sixth group of the baltimore classification?
Group VI, single strand RNA reverse transcript viruses, positive sense RNA with DNA intermediate in life cycle. Examples are retroviruses
What are examples of the seventh group of the baltimore classification?
Group VII, double strand DNA reverse transcript viruses. Examples are hepadnaviruses.
List DNA virus families
H2A2P2P2Y
Hepadnaviridae
Herpesviridae
Adenoviridae
Anelloviridae
Parvoviridae
Papillomaviridae
Polyomaviridae
Poxviridae
What disease or condition can hepadnavirus cause? What can be taken to prevent an infection from the virus?
Hepatitis B, there is a vaccine available to reduce the chance of being infected.
Describe hepatitis B
A hepadnavirus that targets the liver. The infection is usually asymptomatic that can be acute or chronic. The outcomes can be fatal or limiting but the risk of the disease being fatal increases if there is a co-infection with hepatitis D. If the damage progresses the patient may require a transplant.
A patient is tested for Hep B. The patient has HbsAb floating in their system. What does this mean?
Immune system is actively fighting against the virus in other words an active infection.
A patient is tested for Hep B. They have HBsAg and HBeAg only. What does this mean?
Early acute hepatitis B
A patient is tested for Hep B. They have HBsAg, HBeAg, and HBcAb. What does this mean?
The patient has acute or chronic HBV
A patient is tested for Hep B. They have HBsAg, HBeAg, and HBcAb. What does this mean?
Patient is a chronic HBV carrier
A patient is tested for Hep B. They have HBsAb, HBeAb, and HBcAb. What does this mean for the patent?
They are recovering with Hep B immunity.
A patient is tested for Hep B. They hav HBsAb only. What does this mean for the patient?
Distant infection or vaccinated
What virus family causes Hep A?
Picornaviridae
What virus family causes Hep C?
Flaviviridae
What virus family causes Hep E?
Hepeviridae
HAV route of infection, where does in shed the most, and who are usually infected?
Picornaviridae
Fecal-Oral Route
Virus copies found most in feces
Children are most infected
Besides HAV shed in feces, what other frequent sources can it be found on?
Water (contaminated), shellfish, and salads
True or false, is there a cure for HCV?
Yes, drugs are available that can cure HCV with a 95% chance of person reducing risks of cirrhosis and cancer. There are no vaccines available.
What are the long term effects of HCV?
~30% spontaneously clear their infection within 6 months without treatment
~70% develop chronic HCV
* Of the 70%, there is 15-30% chance to develop cirrhosis within 20 years.
What viruses are in the herpes virus family?
HSV-1, HSV-2, VZV, EBV, CMV
Whats the percentage of adults infected with HSV -1 ?
80% its prevalent (oral area and other places)
Whats the percentage of people with HSV-2 infection?
20% infections (genital area)
What are treatment options for HSV infection?
- Acyclovir
- Valacyclovir
- Foscarnet if there is acyclovir resistance suspected
______ people have been exposed to CMV
Most people
Symptoms of CMV can be ______ but reoccur in _______ patients
- Asymptomatic
- Immunocompromised patients
What is the statistics of infection in age five patients for CMV?
1 in 3 have been infected
By age 40, what percentage of people have been infected with CMV?
50% and stays in the body for life
What is a distinguishing feature of CMV?
It can be found almost anywhere on the body unlike other viruses that favor certain tissue. It can be detected in blood, eye, pneumonia, GI tract, and brain
What family is EBV part of?
Herpesviridae, dsDNA
How does EBV spread?
Through saliva. It infects the oropharyngeal epithelial cells and enters B- cells for live.
Describe latent infection of EBV in B-cells
Virus attaches, and infects a healthy B-cell with high efficiency. The infected B-cell is proliferates and eventually becomes immortalized because of viral proteins that result in dysregulation or uncontrolled cell proliferation.
What diseases is associated with EBV?
Hodkin’s lymphoma, hepatitis, gastric cancer, nasopharyngeal cancer, multiple sclerosis, herpes, burkett’s lymphoma, and inflammatory bowel disease.
What kind of conditions can EBV cause in AID patients?
Oral leukoplakia and chronic interstitial pneumonitis
What is the principle of test for mononucleosis?
Monospot test is a latex agglutination test which utilizes equine erythrocytes as the primary substrate and tests for specific heterophile antibodies produced by the human immune system in response to EBV infection. It is 70% - 90% sensitive to the virus.
A positive result is agglutination. A negative is no agglutination observed.
VZV establishes latency where?
DNA virus that establishes latency in the dorsal nerve root ganglions. It reactivates later to cause zoster which is a limited form of varicella.
What is the ideal specimen for a VZV?
Newly formed vesicle before it opens and crusts over.
The virus can be detected by staining cells from the base of the vesicles by culturing cells and vesicular fluid, or by PCR testing of fluid and cells.
Describe HPV
There are over 70 types of HPV. They are considered DNA viruses. Associated with plantar warts, condylomata acuminata, and cervical cancer.
What are guidelines for cervical cancer from the American Cancer Society (ACS)?
- All women should begin cervical cancer testing at age 21
- Women aged 21 - 29 should have a pap test every 3 years. HPV testing should not be used for screening in this age group unless it is needed as after an abnormal pap smear result
- Beginning at age 30, women should be screened with a pap test combined with an HPV test every 5 years as long as the test results are normal. This rule is referred to as co-testing and continues until age 65.
What HPV genes are associated with viral replication and transcription?
E1, E2, E6, and E7.
L1 and L2 are used for protein coat.
In HPV which genes are associated with inactivation of host anti-oncogenes?
E6 and E7
In HPV type 16 and 18, what do they lack?
They lack L1, and L2 genes which are used for protein coats.
In the adenoviridae family, what genus is associated with human infection?
Mastadenovirus, they are associated with respiratory and gastrointestinal diseases. It can dessiminate to multiple organs in compromised hosts.
Which adenovirus serotypes are associated with gastroenterisits?
Adenovirus serotypes 40 and 41.
Which adenovirus serotypes are associated with conjunctivits and keratitis?
All other adenovirus serotypes but not 40 and 41.
How do adenoviruses spread?
Through aerosolized droplets or contact with contaminated respiratory secretions, stool, or fomites. The virus is very stable and can last for weeks . The incubation for respiratory disease is 2 to 14 days.
What is a unique feature of adenoviruses?
The ability to cause severe, acute respiratory disease epidemics in military recruits with considerable morbidity and mortality.
What specimens are appropriate for a suspected adenovirus infection?
Respiratory secretion or stool in cell culture.
JC virus of Polyomaviridae is associated with…?
Causing progressive multifocal leukoencelphalopathy (PML) which is inflammation of white matter at multiple locations.
Parvovirus B19 is associated with…
Fetal loss, erythema infectiosum (slapped cheek syndrome), and aplastic crisis (lysis of erythrocytic precursors)
Poxviridae characteristics are?
Brick-shaped virion with nonconforming symmetry, double-stranded DNA genome..
What viruses are part of poxiviridae?
Smallpox, Monkeypox, and Molluscum contagiosum virus
Retroviruse characteristics
-(+) strand RNA with DNA intermediate
-Retroviruses are unique (+) strand RNA viruses
-dsDNA intermediate is produced from genomic RNA by a viral RNA-dependent DNA polymerase called reverse transcriptase (RT)
-DNA then serves as the template for viral mRNA and genomic RNA synthesis
Whats a key feature of HIV (retrovirus)?
Contains reverse transcriptase
What does reverse transcriptase?
Synthesize DNA from RNA by using the enzyme reverse transcriptase
