2017 Microbiology - Prions, DNA Viruses and Diseases Flashcards Preview

2017 Semester 1 > 2017 Microbiology - Prions, DNA Viruses and Diseases > Flashcards

Flashcards in 2017 Microbiology - Prions, DNA Viruses and Diseases Deck (37):

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?

-Crutzfeldt-Jakob Disease
-Variant CJD

-Gerstmann-Straussler-Scheinker disease (GSS)
-Fatal familial insomina


Characteristics of PARVOVIRUS and example disease

Linear ssDNA
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



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
conjunctivitis and keratoconjunctivitis
gastroenteritis and diarrhea
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
latent infections



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
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?

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
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.