Section 3.2

Question 1

Describe astroviruses

Answer 1

• representative virus = astrovirus
• infections = gastroenteritis in children, elderly, and immunocompromised

Question 2

Describe Hantaviridae

Answer 2

• representative virus = hantavirus (sin nombre virus)
• infection = hantavirus pulmonary syndrome (HPS)

Question 3

Describe calciviruses

Answer 3

• representative virus = noroviruses
• infections = most common cause of infectious gastroenteritis in US

Question 4

Describe Coronavirus

Answer 4

• representative virus = coronavirus
• infection = severe acute respiratory (SARS), cold-like infections, pediatric diarrhea, COVID-19

Question 5

Describe filoviruses

Answer 5

• representative virus = Marburg and Ebola viruses
• infections = hemorrhagic fever

Question 6

Describe flaviviruses

Answer 6

• representative viruses = yellow fever virus, Japanese encephalitis virus, dengue virus, West Nile virus, Zika virus; note: above viruses are Arboviruses (arthropod-borne viruses) AND Hepatitis C virus
• infections = yellow fever, Japanese encephalitis, dengue fever, West Nile virus infection, Zika AND Hepatitis C

Question 7

Describe Orthomyxoviruses

Answer 7

• representative viruse = influenza A, B, and C
• infection = influenza

Question 8

Describe paramyxoviruses

Answer 8

• measles virus = measles (rubeola)
• mumps virus = mumps
• parainfluenza virus = RTI in children
• Respiratory syncytial virus (RSV) = RTI in infants, elderly, immunocompromised
• human metapneumovirus (HMPV) = RTI

Question 9

Describe Picornarvirus

Answer 9

• enteroviruses (polioviruses, coxsackieviruses A and B, echoviruses, enteroviruses) = polio, hand-foot-mouth disease, aspetic meningitis, others
• hepatitis A virus (HAV) = Hepatitis A
• Rhinovirus = common cold

Question 10

Describe reoviruses

Answer 10

• representative virus = rotavirus
• infections = most common cause of gastroenterisitis in infants and children

Question 11

Describe Retroviruses

Answer 11

• HIV-1, HIV-2 = AIDs
• Human T-lymphotropic viruses (HTLV-1, HTLV-2) = T-cell leukemia and lymphoma, tropical spastic paraparesis

Question 12

Describe Rhabdoviruses

Answer 12

• representative virus = rabies virus
• infection = rabies

Question 13

Describe Togaviruses

Answer 13

• rubella virus = rubella (German measles)
• Eastern, western, and Venezuelan equine encephalitis viruses = eastern, western, Venezuelan encephalitis

Question 14

Describe common viruses found in specimens of the central nervous system

Answer 14

• specimens = CSF, throat swab, stool, brain tissue, blood
• enterovirsuses
• HSV
• arboviruses

Question 15

Describe common viruses found in specimens of eye

Answer 15

• specimen = conjunctival swab, corneal scraping
• HSV
• adenoviruses

Question 16

Describe common viruses in specimens of the genital tract

Answer 16

• specimen = genital swap, vesicle swab, or fluid, lesion biopsy
• HSV
• HPV

Question 17

Describe common viruses in specimens of the respiratory tract

Answer 17

• nasal aspirate, throat swab, nasopharyngeal swab, bronchoalveolar lavage, lung biopsy
• influenza A and B
• parainfluenza virus
• adenoviruses
• RSV
• HMPV
• rhinovirus
• enteroviruses
• coronavirus

Question 18

Describe common viruses in specimen of GI tract

Answer 18

• specimens = stool, rectal swab
• adult = noroviruses, adenoviruses, enteroviruses
• infants/children = rotavirus, adenoviruses

Question 19

Describe common viruses in specimens of skin

Answer 19

• specimens = vesicle fluid or scrapings
• HSV, VZV, measles, rubella, enterovirus, parvovirus B19

Question 20

Describe common viruses in specimens of urinary tract

Answer 20

• specimens = urine
• adenovirus
• HSV
• CMV

Question 21

Describe viral specimen collection and transport

Answer 21

• time of collection = during acute phase (1st 3-5 days)
• site of collection = site of infection, entry nad exit sites
• collection container = sterile, leak-proof, nonbreakable
• swabs = Dacron, rayon, or other polyester tips. Plastic or aluminum shafts. Calcium alginate, cotton, wood are inhibitory for some viruses
• transport media = VTM, Amies, or Stuart transport media. Not required for blood, CSF, urine
• transport = deliver immediately. If not possible, keep at 2-8C and deliver within 2 hours. Exception = keep whole blood at room temp.
• storage = best to process upon arrival. If not possible, hold at 2-8C for up to 48 hours, freeze at -70C (not recommended)

Question 22

What are methods of diagnosis of viral infections?

Answer 22

• cytology/histology
• electron microscopy
• direct fluorescent antibody stain
• antigen detection
• shell vial culture
• molecular methods
• serology

Question 23

Describe cytology/histology for diagnosing viral infections

Answer 23

• microscopic examination of specimen for viral cytopathic effect (CPE)

Question 24

Describe electron microscopy for diagnosing viral infections

Answer 24

• rarely used
• labor intensive
• expensive

Question 25

Describe direct fluorescent antibody stain

Answer 25

- fluorescent- labeled antibody added to patient cells fixed to slide - if viral antigen present, antibody binds. - fluorescence seen with fluorescent microscope

Question 26

Describe antigen detection for diagnosing viruses

Answer 26

- solid-phase and membrane ELISAs

Question 27

Describe shell vial culture for diagnosing viruses

Answer 27

- rapid modification of conventional cell culture - detection in 1-2 days - specimen centrifuged onto monolayer of cells growing on coverslip - coverslips stained with viral-specific immunofluorescent conjugate. - used primarily by reference labs

Question 28

Describe molecular methods for diagnosing viruses

Answer 28

- PCR, real-time, PCR, branched DNA, nucleic acid hybridization - faster and more sensitive than cell culture - can detect multiple viruses simutaneously

Question 29

Descibe serology for diagnosing viruses

Answer 29

- detects antibodies in serum - presence of antibodies isn’t always indicative of current infection - useful in evaluating immune status or diagnosing - alternatively, can detect antigen from swabbed site