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286 Cards in this Set

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  • Back
Can viruses replicate outside of another living cell?
No, they are obligate intracellular parasites.
Which virus is shaped like a bullet?
Which viruses are shaped like long cylindrical rods?
Marburg and Ebola.
Which one of the DNA viruses is the only one that does not have iscahedral symmetry?
Pox virus. Its symmetry is complex.
Are viral genomes composed of RNA or DNA?
They may be one of the following: ssDNA, dsDNA, ssRNA or dsRNA, linear or circular.
Can the nucleic acid of a virus be segmented?
Yes. Orthomyxoviruses have 8 segments to their RNA genome.
Which is the only virus that has a diploid genome?
The retroviruses.
What is meant by the term "infectious nucleic acid"?
This means that if only viral nucleic acid were added to a tissue culture, complete virus could be produced. This usually does not happen with viruses that must bring some of their own replicating enzymes into the cell.
What constitutes the nucleocapsid of a virus?
The nucleic acid core of the virus and the capsid (or coat) of the virus.
What is a capsomer?
The individual repeating subunits (building blocks) of the viral capsid.
What is meant by icosahedral symmetry of a virus?
The virus is composed of 20 triangles that form a symmetric figure.
What type of symmetry is called helical?
Capsomers arranged in a hollow coil. The coil may be rigid or flexible.
What is meant by the designation that a virus is enveloped?
The virus has a lipid membrane surrounding the nucleocapsid.
What is a peplomer?
A glycoprotein spike that protrudes from the outer leaflet of a viral envelope.
Where is the "matrix protein" of the viral envelope located?
Associated with the inner leaflet of the membrane.
What is the function of the viral capsid proteins?
To protect the viral genome.
What is the function of the envelope glycoproteins of the virus?
They mediate attachment of the virus to specific host cell receptors.
What is the function of the polymerase of a virus?
It allows replication of the virus genome.
Viruses that are stable to heat, detergents and lipid solvents are enveloped.
The correct answer is: False
What type of virus needs a "helper virus"?
A defective virus.
What term is term applied to an infectious virus particle?
A virion.
What is a pseudovirion?
A virus particle that contains host cell DNA instead of viral DNA and is replication defective.
What is a viroid?
A small circular RNA that can infect plant cells.
What is a prion?
An infectious particle composed solely of protein.
Can a prion be inactivated by the usual agents that inactivate viruses?
Where is the genetic material for the prion located?
It is a cellular gene and part of the host genome.
What is the period of time just after viral infection when no infectious virus can be found?
The eclipse period.
What is the first step in virus replication?
Attachment and penetration.
When does uncoating of the viral genome occur after infection?
Soon after penetration.
Which viral proteins appear first in the infected cell?
The early protein antigens. They are involved in virus replication.
Do double stranded DNA viruses need to bring any replicative enzymes into the cell?
No, they can use host enzymes to replicate their genome and produce proteins.
What enzyme must a RNA+ virus synthesize in the cell in order to replicate?
An RNA-dependent, RNA-polymerase. Host cells do not have this enzyme and the virus must make negative sense RNA from which copies of the genome will be made.
What enzyme must be incorporated into the virus that has a negative sense RNA genome that allows replication in the cell?
A RNA-dependent, RNA-polymerase. The enzyme must be preformed so that it can convert the (-)RNA into a (+)RNA which will be used to make protein and copies of the (-) RNA genome.
What unique enzyme is used to replicate the genome of retroviruses?
Reverse transcriptase. It converts RNA into DNA. Host cells do not have this enzyme.
What is a general theme of protein synthesis used by viruses that is not used by host cells?
Viruses make precursor polypeptides that must be cleaved by proteases into individual peptides.
How are non-enveloped viruses released from an infected cell?
By lysis.
How are enveloped viruses released from infected cells?
By budding through the cell membrane.
What type of nucleic acid comprises the genome of the herpesviruses?
What is the most important characteristic of the herpes viruses?
They can establish latent infection and persist for life.
What are the general features - size and DNA - of the herpesviruses?
Large with a dsDNA genome.
What are the three waves associated with replication of herpesviruses and what is synthesized during each wave?
alpha - immediate early genes and proteins. beta - early genes and proteins. gamma - late genes and proteins that assemble into the capsid.
Where does herpes simplex virus (HSV) establish latency?
Nuclei of the sensory ganglion.
When HSV reactivates where does it go?
It moves to a site at or near the portal of entry.
In what socioeconomic group are more herpes infections found?
Lower socioeconomic.
How many adults are infected with HSV worldwide?
60 to 90 percent.
What correlates with infection with genital herpes?
The number of lifetime sexual partners.
What is characteristic about the pathology of HSV infection?
Formation of multinucleated giant cells. Vesicular lesions containing large quantities of virus.
Where does HSV-1 infection usually occur and what ganglion is colonized?
Infection of the oropharyngeal mucosa. Trigeminal ganglion colonized.
How is HSV-2 usually transmitted and which ganglion is colonized?
Sexual contact. Sacral ganglia.
How does HSV-1 inhibit host responses?
Inhibition of MHC expression. Inhibition of IFN-induced antiviral cascade. Presence of pseudo-Fc receptors. Inhibition of apoptosis of infected cells. Dormancy in neurons.
At what age doe most primary infections with HSV-1 occur?
In children between 1-2 years of age.
Who transmits HSV to newborns?
Nursery personnel and mothers.
Where do recurrent HSV-1 infections occur?
At the vermillion border of the lip.
What are the clinical findings in primary genital (HSV-2) infection?
Macules and papules followed by vesicles, pustules and ulcers.
What are the most common complications associated with HSV-2 infections?
Meningitis and extragenital lesions.
Does the presence of anti-HSV-1 antibodies affect the severity of HSV-2 infection?
Yes, it can ameliorate the infection but does not protect the individual.
What three routes of infection with HSV occur in neonates?
In utero. Intrapartum contact (most by this route). Post-natal acquisition - nursing or transmission via oral lesions.
What are the consequences of neonatal herpes infection?
It is symptomatic and frequently fatal.
What are the three types of infections found in babies infected with herpes simplex virus (HSV)?
Infection of the skin, eye and mouth. Encephalitis with our without skin involvement. Dissemination.
What type of skin infection with HSV is common among health care workers?
Herpetic whitlow.
Who is at increased risk following herpes infection?
The immunosuppressed.
What is the method of choice for diagnosis of herpes infections?
What is used in the treatment of HSV infection?
What is the etiologic agent of chicken pox?
Varicella Zoster Virus (VZV).
What is the etiologic agent of shingles?
Reactivation of prior VZV infection.
What types of clinical features are seen in primary VZV infection?
Pruritic rash accompanied by fever in adults. Usually a self-limiting infection in children.
How is chickenpox transmitted?
By aerosol or by contact with the infected lesion. In utero transmission is possible.
What groups of individuals are susceptible to the development of shingles?
Immunosuppressed. Older patients due to loss of immunity (usually over the age of 50).
Where does the VZV virus replicate after primary infection?
In capillary endothelial cells.
What is characteristic of cells infected with VZV?
Eosinophilic inclusion bodies.
During what seasons is VZV infection more prevelent?
In winter and early spring.
Does zoster occur primarily in winter and spring?
No, it occurs throughout the year.
What patient population is particularly at risk to varicella infection with dire consequences?
Children with leukemia.
What patient population is at increased risk of shingles?
Immunocompromised, especially those undergoing bone marrow transplantation.
What is the pathogenesis of VZV infection?
Infection followed by spread to regional lymph nodes. Multiplication in the lymph nodes. Secondary viremic phase delivers virus to the skin.
What pathologic features are associated with shingles?
Dorsal root ganglion of the affected dermatome exhibits a mononuclear infiltrate and may show demyelination of the axons.
What is characteristic of the rash in shingles?
Occurs in "crops" on the trunk and head.
What is the most frequent complication of VZV infection?
Secondary bacterial infection of skin, lungs or bones.
What is the primary symptom of zoster infection?
Protracted pain or postherpetic neuralgia. Can last for months to years.
What is done to diagnose VZV infection in the laboratory?
Immunofluorescence of scrapings or vesicle for VZV antigen.
What does the presence of persistent VZV antibody in infants mean?
Sign of intrauterine infection.
What is the best way to prevent VZV infection?
What drug is used for treatment of VZV?
Acyclovir. Also used for prophylaxis.
What type of disease does cytomegalovirus cause in the normal human host?
What groups are at risk when infected with cytomegalovirus?
Fetus. Transplant patients. AIDS patients and other immunosuppressed groups.
What is the most common cause of congenital abnormalities induced by viral infection?
CMV infection.
How is CMV transmitted?
Vertically - mother to child. Horizontally - person to person.
What are the primary routes of transmission of CMV?
Intrauterine. Perinatal - via breast milk. Saliva. Sexual contact. Blood transfusion. Organ transplantation.
What is the source for CMV infection in most bone marrow transplant patients?
Reactivation of the virus.
In what patient group should "pre-emptive therapy" for CMV infection be instituted?
In patients with viremia as this probably indicates that the immune system has been overwhelmed.
In what group of patients should suppressive therapy for CMV infection be instituted?
In patients with viruria as there is a direct correlation between virus recovered in the urine and disease symptoms.
What is cytomegalic inclusion disease (CID)?
Disease in babies congenitally infected with CMV - includes growth retardation, jaundice, hepatosplenomegaly, thrombocytopenia, microcephaly and retinitis. Brain damage results in mental retardation, seizures, blindness, deafness. Easier to remember: lots of damage especially to the CNS.
What types of abnormalities are more common than cytomegalic inclusion disease and are a result of intrauterine CMV infection?
Hearing defects or impaired intellectual performance or pneumonitis.
What types of symptoms occur in the occasional immunocompetent individual during primary CMV infection?
Name a major concern regarding organ transplant patients who may develop CMV infection.
Graft rejection may be precipitated by the infection.
What types of problems are found in bone marrow transplant recipients who develop a CMV infection?
Pneumonitis that is life threatening. Delay of marrow engraftment. Increased incidence of graft-vs-host disease (GVHD).
What is the major clinical condition in AIDS patients with CMV infection?
How is CMV infection diagnosed?
Detection of virus in urine, saliva or blood. PCR is probably the best way.
What can be done to prevent spread of CMV to susceptible populations?
Screen tissue and blood for transfusion prior to engraftment.
What is the treatment for CMV infection?
What cell type harbors the Epstein Barr virus (EBV)?
B lymphocytes.
Which is the most common type of EBV virus, EBV-1 or EBV-2?
How does EBV virus enter the human body?
Probably via the oropharynx where it can replicate in epithelial cells.
Does EBV establish a latent infection?
Yes, multiple copies of closed episomal DNA are maintained in B lymphocytes.
When EBV infection causes a primary clinical disease, what is that disease?
Infectious mononucleosis.
At what age does the highest incidence of infectious mononucleosis occur?
15-24 years of age.
What is the "hallmark" of Epstein Barr virus infection?
The presence of "atypical lymphocytes" in the blood. These are activated T cells and NK cells.
What are two complications that can occur as a result of infectious mononucleosis?
Splenic rupture. Airway obstruction. X-linked lymphoproliferative syndrome. Burkett's lymphoma - in Africa. Post-transplant lymphoproliferative disorders. Other malignancies including nasopharyngeal carcinoma.
What is the treatment for patients infected with the Epstein Barr virus?
Supportive. Acyclovir will reduce viral load during primary infection - no effect on establishment of latency.
How is measles transmitted?
Where does primary replication of the measles virus occur?
In the epithelial cells of the upper respiratory tract.
After primary replication of measles virus in the upper respiratory tract, how does the virus spread throughout the body?
Primary viremia spreads the virus to the RES. Secondary viremia seeds skin, respiratory tract and conjunctiva.
What causes the rash of measles?
The interaction of T cells and infected epithelial cells of small vessels.
What are the three "Cs" that are symptoms of measles infection?
Cough. Coryza. Conjunctivitis.
What finding in the oral cavity is indicative of measles infection?
Koplik's spots on the buccal mucosa.
When does measles virus appear in the respiratory secretions?
2 to 4 days prior to the development of the rash.
What are the most important complications that can follow measles infection?
Acute progressive infectious encephalitis. Acute postinfectious encephalitis. Subacute sclerosing panencephalitis (SSPE).
How is measles transmitted?
Aerosolized droplets.
How is measles diagnosed?
Clinical primarily - rash + Koplik's spots. Serology with a four fold rise in antibody titer between acute and convalescent serum- gives information after the disease is over.
What is the best way to prevent measles infection?
A live attenuated vaccine is available. Included in the MMR vacccine (measles, mumps, rubella).
What is the pathogenesis of mumps virus infection?
Spread by droplets. Primary replication in epithelial cells of the upper respiratory tract. Viremia spreads virus to parotid glands and other organs (kidneys, ovaries, testes, CNS).
What is the primary clinical finding in mumps infection?
Enlargement of the salivary glands.
What is the most common problem that may occur in males with mumps infection?
25% may exhibit orchitis.
What other complication is of particular importance during mumps infection?
Development of aseptic meningitis.
How is the diagnosis of mumps made?
Clinical symptoms.
How do you prevent mumps infections?
Live, attenuated virus vaccine (MMR trivalent).
In which groups is the use of the MMR vaccine contraindicated?
Pregnant women. Immunodeficient persons. Persons allergic to eggs or neomycin.
What is the pathogenesis of the rubella virus?
Transmitted by aerosol. Replication in upper respiratory tract and/or local lymph nodes. Viremia distributes virus widely. Skin rash appears.
What is the basis of the skin rash in rubella infection?
Probably an antigen-antibody reaction.
Why is it a concern for nonimmune pregnant women who are exposed to rubella?
Congenital rubella may occur. The worst consequences of infection occur during the first trimester but complications can develop throughout pregnancy.
What is the best way to prevent rubella infection?
The MMR vaccine contains a live attenuated rubella virus.
How do you diagnose rubella infection?
Mimics many other childhood diseases. Serology would give information after the fact but is not often used.
What is the etiologic agent of erythema infectiosum?
The human parvovirus B-19.
How is the B-19 virus spread among the human population?
Via the respiratory route - i.e. droplets.
What cell type is infected by the B-19 virus?
Erythroid precursors.
What is characteristic of fifth disease?
A rash develops. Looks like a cheek that was slapped. After the cheek rash a maculopapular rash appears on the trunk and limbs.
What patient population may develop watery diarrhea as a result of B-19 infection?
In what patient population may a transient aplastic crisis occur as a result of B-19 infection?
Patients with underlying hemolytic disorders.
To what virus group do the enteroviruses belong?
What property of the enteroviruses contributes to their spread in the population?
They can exist for hours to weeks on surfaces, in water and in sewage.
How are enteroviruses spread man to man?
Oral-fecal transmission.
What types of diseases are associated with most enteroviruses?
Colds. Flu-like syndrome. Rashes can occur.
What other and sometime more serious infections can be caused by enteroviruses?
Aseptic meningitis. Exanthema. Mycocarditis.
What types of symptoms can occur due to poliovirus infection?
Flaccid paralysis - damage to the anterior horn cells. Bulbar poliomyelitis - damage to medulla and brain stem, often fatal. Encephalitis - damage to motor cortex.
Post-polio syndrome is characterized by:
Symptoms occurring 30 to 40 years after polio. Muscle weakness. New weakness. Paralysis can occur.
What type of immune response provides protection after vaccination with polio vaccine?
Antibodies neutralize the virus and prevent infection of cells.
What is the advantage of vaccination with inactivated (Salk) polio vaccine?
Does not cause polio, therefore safer.
What is the advantage of the attenuated (Sabin) polio vaccine?
Provides community (herd) immunity. Better for travel to endemic areas. Lifelong protection.
What is the current CDC recommendation regarding use of the polio vaccine?
Use only the inactivated vaccine.
What types of disease are caused by infection with coxsackieviruses?
Aseptic meningitis. Hand-foot-and-mouth disease. Pleurodynia. Acute hemorrhagic conjunctivitis. Herpangina. Mycocarditis.
What is the major cause of diarrhea in infants under the age of 2 years that often requires hospitalization?
What is a major cause of nonbacterial diarrhea in children less than two years and is associated with schools, camps and cruise ships?
Norwalk agent.
Where do infections with HIV-1 occur?
Where is HIV-2 disease primarily found in the world?
West Africa.
What type of genome does the HIV virus have?
+ssRNA - diploid
What enzymes are associated with the HIV genome?
Reverse transcriptase. Integrase.
Where does the HIV virus obtain its envelope?
From the plasma membrane of the host cell.
What other enzyme is associated with the HIV virion?
A protease.
What three genes are common to all retroviruses?
Gag, pol and env
What feature of the HIV virus allows it to use a single promoter for gene expression?
Alternative splicing allows expression of a single RNA transcription product.
Which HIV genetic region contains the structural proteins of the virion?
Which HIV genetic region encodes the enzymatic activities of the virion?
Which genetic region of the HIV virus encodes the proteins in the envelope of the virus?
What is the function of the RNase H enzyme of HIV?
It degrades RNA that is in a heroduplex with DNA. This is needed for synthesis of dsDNA after virus infection of the cell.
What is the function of the tat gene of HIV?
The protein produced from this gene is a transcriptional activator needed for expression of viral genes.
What is the function of the rev gene of HIV?
The protein made from this gene is needed to transport mRNA from the nucleus into the cytoplasm.
In order of their occurrence, name the various stages of HIV infection of a cell?
Attachment. Fusion. Reverse transcription. Nuclear Import of the "Preintegration Complex". Integration. Transcription. RNA Export Translation Assembly and Packaging Release Maturation
What molecule serves as the receptor on T cells to which HIV gp120 attaches?
What two molecules serve as co-receptors on T cells that allow HIV to fuse with the cellular membrane?
What happens during the maturation phase of HIV infection?
The protease of the virus cleaves the polyprotein precursors resulting in structural reorganization of the virion.
What cell type is preferentially infected by the HIV virus?
CD4+ T-lymphocytes
What leads to frequent mutations in the HIV genome?
Infidelity of reverse transcriptase leads to errors. The enzyme has no proofreading capability and therefore mutations occur.
What is the most common HIV clade found in north America?
Clade B
What is used to divide HIV into clades A through I?
The coding sequence of gp120.
How is HIV transmitted?
Sexual contact. Perinatal. Vertical through breast milk. Blood transfusions. Contaminated blood products.
How does HIV infection affect the immune system?
Suppression of cell-mediated immunity due to loss of CD4+ cells.
Besides T cells, what other cell type is infected by the HIV virus?
What component of the immune response is best able to eliminate HIV infection?
CD8+ cytotoxic T cells.
What are the three clinical stages of HIV infection?
Acute - mono-like, viremia which stabilizes to a set point. Latent - viremia low and stays at the set point, ARC occurs. Late or Immunodeficiency - CD4 < 400/mm3, opportunistic infections and cancer.
What is the AIDS-related complex (ARC)?
Clinical condition characterized by persistent fever, fatigue, weight loss and lymphadenopathy. Often progresses to AIDS.
What are the most common clinical manifestations of AIDS?
Pneumocystis pneumonia. Kaposi's sarcoma.
What tests are done to make the laboratory diagnosis of AIDS?
ELISA to detect antibody to HIV (primarily to the p24 antigen). Western blot - to confirm a positive test by ELISA. PCR for viral load - this is also the definitive test during the first month after infection.
What type of HIV drug is Combivir?
Reverse transcriptase inhibitor - AZT/3TC
What type of HIV drug is Viramune?
Non-nucleoside reverse transcriptase inhibitor.
What type of HIV drug is Crixivan?
A protease inhibitor.
How is HIV infection prevented?
Use of condoms. No sharing of needles. Screening of blood and blood products.
What is used for post-exposure prophylaxis for an individual exposed to the HIV virus?
Immediate administration of HAART therapy.
What is used for perinatal treatment to prevent neonatal infection with HIV?
AZT or nevirapine
Should HIV+ mothers breast feed their babies?
What is the most common cause of laryngitis/croup?
Parainfluenza virus.
How are the respiratory viruses transmitted?
Droplets Touching contaminated surfaces (fomites)
How many different serotypes of the influenza virus are described?
Three - type A, type B, type C
Which of the influenza virus types causes the most severe disease and pandemics?
Influenza A
Differences in Influenza A occur due to changes in what components of the virus?
The hemagglutinin (HA) and neuraminidase (NA)
What type of nucleic acid do the influenza viruses have and what is unique about their genomes?
They are (-)ssRNA viruses with genomes that contain 8 RNA segments.
What part(s) of the influenza virus is the target for vaccine production?
The hemagglutinin and neuraminidase
What is the function of the influenza virus neuraminidase?
It cleaves sialic acid and enhances release of the virus, clustering of the virus and binding of the virus by mucus.
How is the diagnosis of influenza made?
Mostly by clinical criteria. Lab tests: culture, immunofluorescence, Z-stat test
What is the cause of major mortality during influenza pandemics?
Secondary bacterial pneumonia.
What is meant by the term "antigenic drift" as applied to influenza virus?
Point mutations in the HA and NA. Occurs in influenza A virus and B virus.
What does the term "antigenic shift" mean in relationship of influenza viruses?
A major change in the virus genome with changes in HA and NA. Due to co-infection of two strains in animals. Responsible for pandemics. Only occurs in influenza A.
What viruses are in the influenza vaccine?
Inactivated viruses of current strain of influenza A and influenza B. Influenza C is not in the vaccine.
What groups should be vaccinated with the influenza vaccine?
Over 50 years of age. Nursing home patients. Those with chronic diseases. Children and teens 6 mo to 18 yrs. Pregnant women who will be in the 2nd or 3rd trimester during the season.
What type of RNA makes up the genome of the paramyxoviruses?
What types of infections are caused by the paramyxoviruses?
Colds. Pharyngitis. Croup. Pneumonia.
How are paramyxovirus infections diagnosed?
Mostly clinical. Lab: culture, fluorescent antibody, ELISA.
What is the danger of RSV infections in children under 1 year of age?
Severe complications occur in 25%
Which viral agent is the leading cause of the croup?
Besides croup, what other diseases are caused by Paramyxovirus 1-4?
Bronchiolitis. Pneumonia. Common cold - in adults.
When is the peak occurrence of paramyxovirus infections?
What type of nucleic acid comprises the genome of adenoviruses?
What part of the adenovirus is responsible for attachment to host cells?
The fibers and the base proteins of the fibers.
What diseases are caused by adenovirus infection?
Fatal disseminated infection in neonates. Coryza in infants. Upper respiratory infection, meningitis and hemorrhagic cystitis in children. Acute respiratory disease in military recruits. Keratoconjunctivitis in adults. Pneumonia and disseminated disease in immunocompromised.
How is adenovirus diagnosed?
Cell culture. Indirect immunofluorescence.
What is the treatment for adenovirus infection?
What type of disease is caused by coronaviruses?
Colds with peak incidence in winter. SARS.
How are corona virus infections diagnosed?
Primarily clinical. Lab tests are available but usually not done.
What is the treatment for corona virus infections?
Why is there no vaccine for the rhinovirus?
Because there are 109 different types of the virus.
Is the hepatitis A virus an RNA or DNA virus?
ssRNA(+) - a picornavirus.
What is the primary route of infection for hepatitis A?
Besides oral-fecal, what are other ways that Hepatitis A infection can be acquired?
Blood exposure on rare occasions. Eating shellfish from contaminated waters.
What groups of individuals are at increased risk for contracting hepatitis A?
Household contacts of a patient. Sexual partners of a patient. Those living in areas of increased incidence. Men who have sex with men. Drug users.
Does hepatitis A ever cause a chronic infection?
NO. It may relapse over the first few months but will finally be cleared.
What laboratory tests aid in establishing the diagnosis of hepatitis A?
Elevated ALT. IgM anti-HAV.
What is the best way to prevent disease as a result of the hepatitis A virus?
Vaccination: formalin-inactivated vaccine is available. For the unvaccinated - gamma globulin after exposure or before travel to an area of high incidence.
Is hepatitis B an RNA or DNA virus?
Partially double stranded, circular DNA
How is hepatitis B transmitted?
Blood. Sexual contact. Mother to newborn.
Does hepatitis B infection ever become a chronic infection?
What is the primary concern for patients chronically infected with the hepatitis B virus?
The increased risk of develop hepatocellular carcinoma.
What are the risk groups for hepatitis B infection?
Multiple sexual partners. Infants of infected mothers. Those emigrating from areas with increased hepatitis B infection. Men who have sex with men. Drug users. Health care and public safety workers. Patients on hemodialysis.
Do patients who are chronic carriers of hepatitis B have symptoms?
Which group of hepatitis B patients can develop cirrhosis of the liver and die of their infection?
Patients with the chronic, active form of the disease.
How is hepatitis B diagnosed in the laboratory?
Elevated ALT. Elevated hepatitis B surface antigen - HBsAg indicates active disease or carrier state - i.e. presence of the virus.
What antibody response indicates immunity to hepatitis B?
Anti-hepatitis B surface antigen - anti-HBsAg
Why is total anti-HBc included in the hepatitis profile, rather than anti-HBsAg?
Because of the "window" period after hepatitis B infection when neither HBsAg nor anti-HBs can be found.
What does the serological profile of a long term hepatitis B carrier look like?
Elevated HBsAg. Elevated anti-HBcAg. No anti-HBsAg.
In what age group would you expect the peak occurrence of hepatitis B infection?
20 to 39 years.
What is the treatment for chronic hepatitis B infection?
What is the best way to prevent hepatitis B infection?
Vaccination: Recombivax is a recombinant form of the HBsAg
What groups should be immunized against the hepatitis B virus?
Healthcare workers. Patients with frequent STDs. Drug abusers. Travelers to Asia and Africa. Newborns and adolescents.
Is hepatitis C an RNA or DNA virus?
Do patients with chronic hepatitis C infection have symptoms?
What is the most serious consequence of having chronic hepatitis C infection?
Chronic liver disease leading to hepatocellular carcinoma (3% of patients).
How is hepatitis C primarily transmitted?
From contaminated blood or body fluids.
Besides blood transmission, what are the other ways to be infected with hepatitis C?
Permucosal - during the perinatal period. Sexual contact - rare.
What are the risk factors for obtaining a hepatitis C infection?
Sharing needles. Administration of clotting factors - not since viral inactivation practices instituted. Transfusions. Therapeutic interventions using needles. Accidental needle sticks to healthcare workers.
What laboratory tests help establish the presence of hepatitis C infection?
Elevated ALT. Anti-HCV ELISA followed by RIBA. PCR for presence of the virus.
Does the anti-HCV titer indicate recent infection?
No. The test measures total anti-HCV not IgM anti-HCV.
What does the hepatitis D virus need in order to be able to replicate?
Must have the hepatitis B virus - The hepatitis D virus is a defective virus.
In which group would you expect to find the most severe disease - hepatitis B infection only or coinfection with hepatitis B and hepatitis D?
In the coinfection with hepatitis B and hepatitis D. More likely to develop fulminant hepatitis.
What is the potential risk for a hepatitis B carrier who becomes superinfected with the hepatitis D virus?
The risk of development of cirrhosis of the liver.
What serologic profile is seen during super-infection of the hepatitis B carrier with the hepatitis D virus?
Anti-HDV will remain elevated. Anti-HBs elevated.
What is the serologic profile in patients co-infected with the hepatitis B and hepatitis D viruses?
Total anti-HDV will return to baseline. Anti-HBs will remain elevated.
What is the best prevention for hepatitis D infection?
Same as for hepatitis B. Educate hepatitis B carriers concerning the risks associated with hepatitis D superinfection.
Where are cases of Hepatitis E occur?
Asia, Africa, India, Mexico and travelers to these areas.
What are the clinical features infection with Hepatitis E?
The same as Hepatitis A. Transmitted by the oral-fecal route. A self-limiting disease.
What changes occur in a cell that has undergone malignant transformation?
Altered morphology. Altered growth control with loss of contact inhibition. Altered DNA synthesis, karyotype and antigens. Biochemical alterations - lower cAMP and others.
Carcinogenesis is the multi-step process requiring multiple "hits".
The correct answer is: True
Viruses that cause cancer generally cause an acute viral infection.
The correct answer is: False
Transformation of non-permissive cells leads to expression of viral early genes that are sometimes oncogenic.
The correct answer is: True
Tumor cells induced by viruses have viral genes integrated into their DNA.
The correct answer is: True
List some common molecules that serve as oncogenes.
Growth factors. Growth factor receptors. Signal transduction proteins - G proteins, tyrosine kinases. Second messengers. Cell cycle control regulators - usually transcription factors.
List two tumor suppressors.
p53. Rb.
What is the origin of oncogenes found in RNA viruses (retroviruses)?
Interact with cellular tumor suppressors or oncogenes. Used in the virus cell cycle.
When do oncogenes cause cancer?
When they are overexpressed. When they are mutated.
Several types of classification schemes for retroviruses have been used in the past
however the newest classification depends upon what properties of the virus?
What is meant by the term "simple" retrovirus?
A virus with essential gag, pro, pol and env genes.
What is a "complex" retrovirus?
These retroviruses use multiple splicing to express several additional regulatory and accessory genes.
What two things can cause cancer by "acute transforming" viruses/
Overexpression of the oncogene by the viral promoter. Increased activity of the viral gene due to mutation.
What is the mechanism of carcinogenesis by "slow transforming" viruses?
Insertional activation of a cellular oncogene (could be de-activation of a tumor suppressor.
How does HIV promote the development of cancer?
Suppression of immune surveillance.
What type of cancer does the HTLV-1 virus induce?
T cell lymphomas in adults.
Besides cancer, what other disorder occurs due to HTLV-1 infection?
HTLV-1-associated myelopathy/ tropical spastic paraparesis.
What role is the tax gene thought to play in oncogenesis by HTLV-1?
May play a role through interaction with cell cycle regulators.
What type of cancer is associated with hepatitis C infections?
Hepatocellular carcinoma
What antigen of the papovaviridae must be expressed for the production of the transformed state?
The "T" antigen.
Name two viruses among the polyomaviridae that occur in immunosuppressed humans and can transform rodent cells in vitro.
BK virus. JC virus.
Which virus can cause warts, cervical cancer and oropharyngeal cancer?
Human Papilloma Virus (HPV)
What HPV proteins are expressed in cancer cells and interact with p53 or Rb?
E6. E7.
Which of the early antigens of adenoviruses are responsible for transformation of rodent cells?
E1A. E1B.
What does adenovirus E1A complex with in host cells?
What does adenovirus E1B complex with in host cells?
What 5 types of cancer are associated with Epstein-Barr virus infection?
Burkitt's lymphoma in Africa. Nasopharyngeal carcinoma. Post-transplant lymphomas. Hodgkin's disease. AIDS-associated cancers.
What is the cause of Kaposi's sarcoma and primary effusion lymphoma (PEL)?
What is the viral oncogene of Kaposi's sarcoma?
LANA (latency associated nuclear antigen)