Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
56 Cards in this Set
- Front
- Back
|
What are the 3 classes of mRNA in Herpes viruses?
|
alpha polypeptides - function not clear, may be related to latency
beta polypeptides - virus specific thymidine kinase and DNA polymerase (important targets for development of antivirals). Synthesis of beta polypeptides shuts off synthesis of alpha polypeptides and initiates synthesis of gamma polypeptides Gamma polypeptides - structural components of virus particle |
|
|
Herpes virus stucture
|
dsDNA
Enveloped - buds through nuclear membrane Linear genome, which becomes circular during latency state |
|
|
Where is the site of Herpes simplex 1 latent infection?
|
Trigeminal nerve root ganglion
|
|
|
Herpetic whitlow
|
Cause by HSV-1 and HSV-2
|
|
|
Clinical manifestations of herpes simplex viruses
|
Herpetic whitlow - Infection of finger or nail. Result of inoculation of cut, abrasion with secretions - often from patient's own saliva. Painful vesiculating, pustular lesions.
Corneal and conjunctival infections - may lead to conjuctival scarring and blindness. Characterized by distinct dendritic ulcerations: pathognomonic. DO NOT GIVE TOPIC STEROIDS Encephalitis - up to 10% of all cases of viral encephalitis. Devastating illness - mortality untreated about 70%, survivors often have extensive neurologic deficits. Intravenous acyclovir decreases mortality. |
|
|
What are the rates of recurrent genital herpes?
|
80% of primary infections lead to latency and recurrence
Median recurrence rate is 4-5 episodes per year |
|
|
Neonatal herpes
|
Usually results from contact with infected genital secretions of mother during delivery.
Lack of normal immune response in neonate leads to devastating, disseminated disease: overall mortality rate of 60%, high rate of neurologic sequelae in survivors. |
|
|
Cytomegalovirus
|
dsDNA
Enveloped Isolated from saliva, cervical secretions, semen, urine, and white blood cells (specifically neutrophils) Infects epithelial cells ("owl's eye effect") and leukocytes Congenital infection is really bad |
|
|
Congenital CMV infection during pregnancy
|
Most infants appear normal
20% develop sensory nerve hearing loss, psychomotor mental handicap, or both Almost all infants with congenital infection are born to mothers who experience primary infection pregnancy |
|
|
Epstein-Barr virus
|
dsDNA
Enveloped Can be isolated only from lymphoblastoid cell lines derived from human B cells Does not produce cytopathic effect No vaccine |
|
|
What antibody is diagnostic of acute infectious mononucleosis?
What about chronic? |
Acute: IgM anti-VCA (viral capsid antigen)
Chronic: anti-EBNA (nuclear antigens) |
|
|
Which malignancies are associated with Epstein-Barr virus?
|
African Burkitt's lymphoma
Anaplastic nasopharyngeal carcinoma B-cell lymphomas |
|
|
Which cells does Epstein-Barr virus infect and through which receptor?
|
Cell - B cells
Receptor - C3d (complement) receptor |
|
|
What are heterophile antibodies?
|
Unrelated antibodies of IgM class which respond with all kinds of crazy antigens
Probably due to polyclonal activation of B cell by Epstein-Barr virus |
|
|
What are the laboratory diagnoses for Epstein-Barr virus infection?
|
Detection of heterophile antibodies and detection of specific pattern of anti-EBV antibodies
|
|
|
What percentage of the mammalian genome is made up of endogenous retroviruses?
|
10%
|
|
|
What are the human retroviruses?
|
HIV
human T-cell leukemia virus type 1 and 2 (HTLV-1 and HTLV-2) |
|
|
Tat gene (HIV)
|
Major transcriptional transactivator of HIV-1 and essential for the activity of the LTR promoter. The Tat protein stimulates HIV-1 transcription via an RNA intermediate called the TAR region, which is found just downstream of the 5'LTR.
|
|
|
Rev gene (HIV)
|
Rescues the unspliced viral RNA from the nucleus of infected-cells by increasing transport through the nuclear pore.
|
|
|
Vpu gene (HIV)
|
Stimulates viral release.
|
|
|
Vif gene (HIV)
|
Prevents hypermutation of viral genome by cellular deaminase APOBEC3G.
|
|
|
Human Papillomavirus (HPV)
|
dsDNA
Non-enveloped Small Transformation ability Virions only produced in cornified epithelium HPV types 6 and 11 - associated most frequently with benign genital warts in males and females; associated with some instances of cervical dysplasia in females; lesions only rarely become malignant. HPV types 16, 18, and 31 - Cause warty lesions of vulva, cervix, penis, and anus; more often progress to malignancy |
|
|
What changes are seen in cells infected with HPV?
|
Perinuclear cytoplasmic vacuolization, nuclear enlargement, and other changes in epithelial cells of the cervix and vagina.
Seen in pap smears |
|
|
What strains of HPV does Gardasil create immunity for?
|
Types 16, 18, 6, and 11
|
|
|
JC virus
|
dsDNA
Non-enveloped Small Transformation ability Diagnosis - urine from patients excreting polymoa viruses may contain cells similar to those found in patients excreting CMV; Immunoassays can also demonstrate viral antigens. Diseases caused : Progressive Multifocal Leukencephalopathy (PML) and urinary tract infection |
|
|
Progressive Multifocal Leukoencephalopathy (PML)
|
Associated with JC virus
Virus reactivates in immunocompromised individuals (i.e. AIDS). Causes subacute, degenerative disease of the brain. Symptoms: - Impaired memory, confusion, and disorientation initially - Followed by hemiparesis, visual disturbances, incoordination, and seizures - Progressive; death occurs 3 - 6 months after onset of symptoms CSF testing often normal; foci of demyelination due to damage to oligodendroglial cells; JC virus particles visible by EM No treatment, except reduction in immunosuppression if possible |
|
|
BK virus
|
dsDNA
Non-enveloped Small Transforming ability Causes urinary tract infections and hemorrhagic cystitis in bone-marrow transplant patients BKV can be readily isolated in fibroblasts and other cells |
|
|
Rabies virus
|
ssRNA
Enveloped Bullet-shaped Virus enters unmyelinated peripheral nerves, possibly by attachment to Ach receptor; virus travels to CNS (replication and assembly of mature virions); Virus migrates from CNS through nerve terminals of organs, especially salivary glands Incubation period: Typical - 4 to 6 weeks Range - 7 to 10 days to 7 to 8 years |
|
|
Rabies vaccine and immune globulin
|
Vaccine - human diploid cell vaccine commonly employed in USA; active induction of virus neutralizing antibody in 7 to 10 days; IM administration most common
Rabies immune globulin - rapid, passive viral neutralization (but short duration); HRIG - human origin, prepared from pooled rabies-immune donor sera |
|
|
Clinical manifestations of hepatitis A virus
|
Incubation period 14-40 days (mean 25 days)
Liver enlarged and tender; abnormal liver function tests Chronic HAV rare or non-existant; fulminant, fatal hepatitis associated with extensive liver necrosis can occur Immune serum globulin (ISG) - 80-90% effective Vaccine - administered as 2 doses, recommended for all infants 1 year of age |
|
|
Hepatitis B virus replication cycle
|
Involves reverse transcription step, unique to DNA viruses.
One strand, short strand of variable length, is associated with viral DNA polymerase and is positive-sense. Other strand, long strand, is completely and of negative-sense. Full length viral positive sense RNA transcripts are inserted into maturing core particles; these mRNAs serve as templates for reverse transcriptase that synthesizes a full length negative sense DNA strand. Positive sense DNA strand is initiated but not completed prior to virus maturation and release. |
|
|
Hepatocellular carcinoma is strongly associated with what virus?
|
Hepatitis B virus
|
|
|
What symptom of HBV is not typical of HAV?
|
Rash or joint pain
|
|
|
Hepatitis B prevention
|
Hepatitis B immune globulin - emergency measure
Vaccine - recombinant vaccines; immunization requires 3 doses Infants born to infected mothers require a combination of passive and active immunization Active immunization recommended for all infants (first dose on day of birth) |
|
|
Hepatitis B treatment
|
No good treatment
Some use for interferon, some use for lamivudine (reverse-transcription inhibitor) |
|
|
Hepatitis D
|
ssRNA
Small Requires presence of HBsAg for transmission but not replication Causes rapid progression of disease already present with HBV |
|
|
Hepatitis C
|
ssRNA, actually a flavivirus
Chronic carrier state is common - 70% of those infected Transmitted by blood Greatly increased risk for liver cancer; one of the 3 most common reasons for liver transplantation Tx - best results w/ pegylated INF-alpha and ribavirin |
|
|
Clinical disease manifestations and outcomes for polio
|
Abortive poliomyelitis - nonspecific febrile illness, 3 - 5 days duration, no signs of CNS involvement.
Aseptic meningitis - non paralytic poliomyelitis; signs of mental irritation (stiff neck, pain & stiffness in back), no permanent effect. Paralytic poliomyelitis - asymmetic flaccid paralysis, no significant sensory loss. Extent of nerve involvement varies: all four limbs may be involved, or brain stem may be involved - leading to respiratory problems. |
|
|
What are the 2 types of polio vaccine?
|
Inactived polio vaccine - "Salk" vaccine
Oral polio vaccine - live, attenuated vaccine; "Sabian" vaccine Recent recommendation in USA: 2 doses of IPV, followed by 2 doses of OPV |
|
|
Most common manifestations of coxsackieviruses and echoviruses
|
Aseptic meningitis - usually mild and self-limited, often characterized by sufferers as "the worst headache you've ever had in your life." Encephalitis is possible, but rare.
Rashes - usually in children. Best example is hand-foot-and-mount disease; frequently associated with coxsackievirus A16 and enterovirus 71. Acute inflammation of the heart muscle (myocarditis); group B coxsackieviruses are the most frequently implicated. |
|
|
Rhinoviruses
|
(+) ssRNA
Optimum temperature is 33 degrees C Incubation period 2-3 days Duration of acute symptoms about 3-7 days Frequent causes of the "common cold" Epidemic peaks in early fall or spring No vaccines, no specific therapy |
|
|
Rotavirus
|
dsRNA, 11 segments, no envelope, but 3 concentric capsids
1-3 day incubation period Abrupt onset of vomiting, followed quickly by watery, brown, copious stools; stools may become clear; low-grade fever often present. Vomiting: 1-3 days Diarrhea: 5-8 days Vaccine - first one caused intussusception (Rotashield); RotaTeq now routine vaccination of US infants By age 4, 90% of children have serum antibodies |
|
|
Norwalk viruses
|
ssRNA, non-enveloped, small
Brief illness - 1-2 days Similar symptoms to Rotavirus Protective effect of antibodies appears minimal; reinfection/illness with same serotype occurs repeatedly Common source of outbreaks associated with water - uncooked shellfish No vaccine available; by 5th decade of life, 50% of people have antibodies |
|
|
What are the laboratory tests for Rotavirus?
|
ELISA assay to detect virus Ag in stool specimens
|
|
|
What is the immune response to Rotavirus?
|
Type specific serum (IgG) and secretory antibodies (IgA) - long lasting, probably protective
Breast feeding seems protective (probably via transfer of maternal IgA) |
|
|
Enquine Encephalitides
|
(+) ssRNA
Buds through host cell membrane All mosquito transmitted Natural reservoir of these diseases is birds and small animals Incubation period 4 to 21 days; sudden onset of severe headache, chills, fever, nausea, vomiting, generalized pain, and malaise. Within 24 to 48 hours, marked drowsiness, stupor may occur (invasion of CNS); nucchal rigidity common. Mental confusion, tremors, convulsions, coma may develop in severe cases. Fever lasts 4 to 10 days. Sequelae: mental deterioration, personality changes, paralysis, aphasia, and cerebellar signs. No immunzation available |
|
|
St. Louis Encephalitis (SLE)
|
(+) ssRNA
Mosquito is vector Similar to equine encephalitides |
|
|
Japanese B Encephalitis
|
Endemic to Japan and China
Vector is mosquito, swine are important reservoir host |
|
|
Yellow Fever
|
(+) ssRNA
Initial multiplication of virus in regional lymph nodes; viremia and dissemination to liver, spleen, kidney, bone marrow, and other lymph nodes. Secondary multiplication of virus, cellular destruction. Destruction of liver cells leads to jaundice. Death may occur from necrosis of liver or kidney. Clinical findings: incubation period 3 to 6 days. Fever, chills, headache, backache, nausea, and vomiting. Short period of remission. Day 4, serious symptoms develop: slow pulse, jaundice, hemorrhagic phenomena, signs of kidney damage. Live attenuated vaccine available |
|
|
Dengue (Breakbone Fever)
|
(+) ssRNA
In most respects similar to Yellow Fever, except site of virus is in small blood vessels, not regional lymph nodes Clinical findings: Fever, possibly after prodrome of malaise, chills, and headache. Pains soon develop in back, joints, muscles, and eyeballs. Temperature returns to normal, may rise again ("saddleback" fever curve). Rash may develop on 3rd or 4th day (secondary viremia), lasts 1 to 3 days, disappears with desquamation. Convalescence may take weeks. Death is rare Variant: Denge hemorrhagic fever No vaccine |
|
|
Dengue hemorrhagic fever
|
Occurs in individuals with passively acquired maternal antibody or in those repeatedly infected with heterologous strains of dengue virus; an immune phenomenon.
Initial course resembles normal dengue infection. Manifestations of coagulation abnormalities appear (shock, bleeding). Caused by plasma leakage through damaged endothelial cells; shock is hypovolemic. |
|
|
California encephalitis
|
(-) ssRNA
Enveloped Buds on Golgi apparatus Clinical findings: Abrupt onset, typically with severe bifrontal headache, fever of 38-40 C, sometimes vomiting or lethargy or convulsions. Prognosis good, though convalescence may be prolonged. Natural hosts probably small woodland mammals |
|
|
Lassa Fever
|
(-)ssRNA
Enveloped Double-segmented Probably transmitted by contact with rodent urine High fever, mouth ulcers, severe muscle aches, skin rash with hemorrhages, pneumonia, heart and kidney damage. Often fatal when contracted as an adult Ribavirin is reportedly effective in Tx |
|
|
Lymphocytic Choriomeningitis Virus
|
(-)ssRNA
Enveloped Double-segmented Presents as either aseptic meningitis or as mild flu-like illness. Probably transmitted by contact with or inhalation of mouse droppings and urine No specific therapy Transplacental transmission - for God's sake stay away from hamsters |
|
|
Marbug virus
|
(-) ssRNA
Hemorrhagic fever - bleeding from mucosa, shock, and virus is located in all body secretions |
|
|
Ebola virus
|
(-) ssRNA
Hemorrhagic fever - bleeding from mucosa, shock, and virus is located in all body secretions |
