2017 Microbiology - Prions, DNA Viruses and Diseases Flashcards
Understand the PrP gene, PrPc protein and what changes take place in protein structure to cause disease
PrP found on chromosome 20
creates the protein PrPc which undergoes gylcosylation to become PrPsc -> structural change from a-helix to b-sheet.
B-sheet forms peptide aggregates to make amyloid fibrils
What is the difference between horizontal and vertical transmission?
Horizontal - one person to another via contact (ingestion, transplant, etc.)
Vertical - familial cases, prior gene
What are some examples of acquired prion diseases and examples of inherited prion diseases?
Acquired:
- Kuru
- Crutzfeldt-Jakob Disease
- Variant CJD
Inherited:
- Gerstmann-Straussler-Scheinker disease (GSS)
- Fatal familial insomina
Characteristics of PARVOVIRUS and example disease
Linear ssDNA
icosahedral
naked
smallest DNA virus
Erythrovirus B19
Erythrovirus B19 (Parvoviridae) Transmission, Pathology, Disease, Dx.
TRANS: respiratory droplets or transplacental, Nasopharynx -> bone marrow, kills erythroid precursors
PATH: 1. Viremia and anemia, 2. Immune response (rash and arthralgia)
DISEASE: late winter/spring
-fifth disease (slapped face rash)
-aplasitc crisis in chronic hemolytic anemia pts
-acute polyarthritis
-spontaneous abortion
DX: clinical presentation, ELISA, PCR
Characteristics of PAPILLOMAVIRUS and example disease
DNA, naked, icosahedral, dsDNA
Prickled appearing virus
HPV
Which types of HPV cause warts and which are associated with cancers?
Type 1-4 cause warts
Types 16, 18 (31,45 less common) associated w/ cancer
What is the pathology of HPV?
warts appear in keratinized skin which stimulates hyperplasia
Koilocytes develop = enlarged keratinocytes with clear halos around condensed nuclei.
What are diseases of HPV?
Papillomas (warts) - children/young adults
Laryngopapillomas: infant to 50 yo., single, peduculated, can block airways in infants
Anogenital (condylomata acuminata)
Cervical dysplasia, CIN & carcinoma
Characteristics of POLYOMAVIRUSES and example disease
Naked, DNA virus
2 diseases: BK & JC
typically only symptomatic in IC patients
POLYOMAVIRUS (JC & BK) epidemiology key points, what CNS cell is targeted by injection?
enters via respiratory droplets, goes to epithelia cells then lymphocytes -> travels to kidneys
in lytic infectious there is demyelination of oligodendrocytes.
Which Polyomavarius causes the following:
Hemorrhagic cystitis, nephritis and/or urethritis?
Progrssive multifocal leukoencephalopathy?
BK virus
JC virus
Characteristics of ADENOVIRUSES? What does it do to MHC 1 Receptors, and why is that important?
linear dsDNA, icosahedral, naked
has a characteristic long fiber extending from capsomer at corners which are hemagglutinators
Can down regulate MHC Class 1 receptors thus helping the infection avoid Tc cells.
Examples of diseases/conditions caused by ADENOVIRUS
acute febrile pharyngitis and pharyngoconjunctival fever acute respiratory tract disease Colds conjunctivitis and keratoconjunctivitis gastroenteritis and diarrhea Intussesception sepsis in IC patients acute hermorrhagic cystitis
How is Adenovirus dx? What are some cytological clues?
ADV produces nuclear inclusion bodies.
ADV is cultured in epithelium derived cells
Characteristics of HERPESVIRUSES and example disease
dsDNA, enveloped, Icosahedral
8-types
latent infections
HSV1, HSV2, VZV, EBV
What are example symptoms and complications caused by HSV-1 infection?
Mucocutaneous infection
Acute hepatic gingivostomatitis
Herpes labialis
Herpetic whitlow - lesion of distal phalanx
Encephalitis - dx w/ MRI and CSF (PCR for HSV)
What are some DX. tests for HSV-1
Tzanck smear or Pap test of material from vesicle -> shows syncytia and Cowdry type 1 intranuclear inclusions
What are example symptoms and complications caused by HSV-2 infection?
Genital herpes
Herpes urethritis
Perinatal infection & encephalitis - if mother infected
Herpes pharyngitis
What are example symptoms and complications caused by Varicella-zoster virus (HSV-3) infection?
VZV or chickenpox virus
Shingles - zoster
Pneumonia - adults and IC patients
Prenatal infection - CNS abnormalities when fetus infection <20 weeks, neonates may show skin lesions
What are example symptoms and complications caused by Epstein-Barr Virus (EBV/HHV-4) infection?
invades oral epithelial cells and B cells (tonsil).
Mononucleosis refers to T-cell lymphocytosis and typical lymphocytes (Downy cells)
Infectious mononucleosis laryngitis hepatitis encephalitis, aseptic meningitis burkitt's lymphoma, Hodgkin's lymphomas Nasopharyngeal carcinoma Hairy oral leukoplakia (in AIDS pts)
What are DX tools for Epstein-Barr Virus (EBV/HHV-4) infection?
clinical picture - namely malaise
atypical lymphocytosis
heterophil antibody
viral capsid antigen specific antibody
Explain the epidemiology of Cytomegalovirus (HHV-5) infection? What are some ways it is acquired?
it is a common lymphotrophic lifelong recurrent infection.
Acquired transplacentally or during birth, from milk, saliva, tears, urine in infants, and semen (a major route), or blood in adults.
What are some example diseases of Cytomegalovirus?
CMV Mono - similar but more mild than IM
Cytomegalic inclusion disease - fetal and IC patients, can be fatal. MOST COMMON VIRAL CAUSE OF CONGENITAL DEFECTS
transplant/transfusion infections - severe in neonates and IC pts
What are some example DX techniques for Cytomegalovirus?
Owl’s eye inclusion/cells
Explain the epidemiology of Human B-lymphotropic virus (HHV-6,7) infection? What disease is associated with infection?
is a common lymphotrophic (t-cell) viral infection of infants or very young children
results in Roseola infantum
Sx. high very (103-105) w/ rapid onset, can induce febrile seizures
Explain the epidemiology of HHV-8 or Kaposi’s sarcoma assoicated virus infection? What are some ways it is acquired?
STD
AIDS associated
results in Kaposi’s sarcoma in AIDS patients - CT cancer resulting in dark skin spots
Characteristics of POXVIRIDAE and example disease
dsDNA, complex symmetry, two membrane layers, brick or ovoid shaped
largest of all viruses
replication occurs in cytoplasm and use viral DNA-dependent RNA polymerase
Variola virus Molluscum contagiosum virus Cowpox Monkeypox Orf Virus
What are some epidemiological features of Variola Virus and disease it causes?
virus initiates quickly, human-to-human contact via droplets or contact.
starts respiratory and spreads via lymphatics
rash on skin that becomes herorrhagic
Example: Smallpox
What are some epidemiological features of Molluscum Contragiosum Virus and disease it causes?
slowly developing infection spread by contact
AIDS association
Skin develops flesh-color or white smooth, waxy bumps w/ dimple in center
Example: Molluscum Contagiosum: lesions found on trunk or genitalia (adults)
Dx: large, eosinophilic, scallop shell like inclusions in epithelia cells
What are some epidemiological features of Cowpox, Pseudocowpx, Vaccina Viruses and symptoms it causes?
Zoonotic disease, slowly developing, self limiting
results in singular, vesicular, pustular or hemorrhagic lesions on finger, hands or arms
What are some epidemiological features of Monkeypox Virus and symptoms it causes?
zoonotic disease from monkeys
appears like smallpox
What are some epidemiological features of Orf Virus and symptoms it causes?
zoonotic disease from sheep
single, nodular, or granulomatous lesions on fingers, hands, arms.
contagious pustular dermatitis, an epithelial cell infection
Characteristics of HERPADNAVIRIDAE and example disease
partially dsDNA
Hepatitis B
Explain the pathology of Hep. B Infection?
HBV is liver tropic; can integrate into hepatocyte DNA in cases of hepatocarcinoma. Normally, viral replication does not involve integration into the host chromosome. CMI is critical to recovery; Tc kill HBsAg expressing hepatocytes
What are some clinical Sx. of Hep. B infection?
Dark urine
Jaundice and scleral icterus
What are diseases associated with Hep. B infection?
Type B hepatitis, serum hepatitis (long incubation hepatitis) – insidious development of icterus (yellow skin, dark urine, pale stools), fever, upper right quadrant pain, increased liver enzymes in blood, anorexia, nausea and malaise; 5-10% develop chronic hepatitis and cirrhosis, especially perinatally infected infants.
HBV-HDV Co-infection: fulminant, fatal cases of serum hepatitis.
Primary hepatocellular carcinoma – highly fatal cancer, 80% associated
with chronic hepatitis.
