Chapt 29 Virology

Question 0

Complement fixation

Answer 0

Activation of complement proteins

Question 1

Capsid

Answer 1

Protein covering a virus

Question 2

Cytopathic effect

Answer 2

Visible changes in cell cultures resulting from toxins or infection by a virus

Question 3

Interferon

Answer 3

Class of mediators that increase the resistance of cells to viral infection by inhibiting viral replication & the growth of some euplastic cells

Question 4

Viruses

Answer 4

Obligate intracellular parasites with 2 basic components: genetic component (DNA/RNA -not both) & Protein coat, some have lipid outer envelope

Question 5

Viral Replication Steps

Answer 5

Attachment-virus attaches to host cell receptor sites
Endocytosis- viral penetration into the host cell
Eclipse phase- synthesis of viral components by host cell
Maturation- reassembly of viral components
Release- virus leaves the host cell

Question 6

DNA viruses replicate in the?

Answer 6

Host’s cell nucleus

Question 7

RNA viruses replicate in the?

Answer 7

Host’s cell cytoplasm

Question 8

How are viral envelopes acquired?

Answer 8

From the host cell’s membrane as the virus leaves the host cell

Question 9

Treatment of viral infections

Answer 9

Antibiotic have no anti-viral properties, anti-virals inhibit viral replication process

Question 10

Passive vaccines

Answer 10

Contain preformed anti-viral antibodies, can be useful to prevent disease after exposure

Question 11

Active vaccines

Answer 11

Stimulates the host to make its own antibodies, can prevent infection prior to exposure: live virus, attenuated (non-pathogenic), & killed virus

Question 12

Viruses can only replicate?

Answer 12

in vivo (inside living cells)

Question 13

Tissue culture

Answer 13

Living cells are utilized to grow viruses (difficult, expensive, & slow)

Question 14

What temperature should viral specimens be stored during transport or storage?

Answer 14

4 degrees C

Question 15

Herpes Simplex Virus

Answer 15

DNA Virus group, most common human virus

Question 16

HSV1

Answer 16

Oral infections in children/young adults “above the waist”, acquired through oral contact & respiratory droplets

Question 17

HSV2

Answer 17

Genital lesions “below the waist”, acquired through sexual contact/childbirth, neonatal HSV infections can cause death or retardation

Question 18

Respiratory Syncytial Virus (RSV)

Answer 18

DNA virus (paramyxovirus), most common cause of respiratory infection in children <1yr, virtually all contact it by age 3, major role of pathogenesis of asthma, significant morbidity & mortality in immuno-deficient, transmitted through respiratory secretions, best detected by Direct Antigen Tests from nasopharyngeal washings

Question 19

Hepatitis A (HAV)

Answer 19

RNA virus (enterovirus), infectious hepatitis, fecal contamination of food & water, 1month incubation, liver dysfunction & jaundice
Symptoms: jaundice & malaise, elevated liver enzymes
Antibodies: anti-HAV (IgG)=past infection, anti-HAV (IgM)=acute infection

Question 20

Hepatitis B (HBV)

Answer 20

DNA virus “Dane particle” (Hepadnavirus) “serum hepatitis” acquired from percutaneous routes, sexual contact, transfusions, 3 month incubation, liver dysfunction & jaundice, most serious threat to healthcare workers

Question 21

Hepatitis C (HCV)

Answer 21

RNA virus (flavivirus) formerly "Non-A/Non-B hepatitis" (NANB), acquired from transfusions, sexual contact & percutaneous routes, 5-10 wk incubation, sub-clinical infection for years prior to chronic liver disease
Diagnosis: elevated liver enzymes & anti-HCV antibodies

Question 22

Hepatitis D (HDV)

Answer 22

RNA virus, super infection-only infects cell already infected with HBV, acquired via sexual contact, transfusions, diagnosed by detecting anti-HDV antibodies

Question 23

Human Immunodeficiency Virus (HIV)

Answer 23

RNA virus (retrovirus), causative agent of AIDS (HIV 1,2,3) acquired via sex, percutaneous routes, transfusion & mother to newborns, prolonged incubation (wks to yrs)

Question 24

Western Blot Test

Answer 24

Utilizes purified HIV antigens to confirm preliminary (+) serological tests

Question 25

HIV infects which cells?

Answer 25

CD4+ (T-lymph helper cells)

Question 26

HIV infection rates?

Answer 26

40,000,000 worldwide, 25,000,000 in sub-Sahara Africa, increasing in China, India, Southeast Asia & Eastern Europe
950,000 infections in US, 20 in every 100,000 people, 40,000 new cases each yr, in 2003 18,000 HIV deaths

Question 27

Varicella-Zoster Virus

Answer 27

DNA virus, acquired via inhalation & dissemination through lymphoid tissue: children-chicken pox, adults-shingles

Question 28

Cytomegalovirus (CMV)

Answer 28

DNA virus, ubiquitos worldwide, flu-like symptoms, severe infections in the immuno-compromised & newborns
Blood products can be screened for CMV antibody, indicating prior exposure, CMV(-) blood products are often requested for immuno-compromised patients

Question 29

Influenza Virus

Answer 29

RNA virus (Orthomyxovirus) common respiratory infection, acquired via inhalation of aerosols & direct contact, annual winter time influenza season, 36,000 deaths/yr, opportunistic pathogen, antigen drift makes manufacture of vaccines an educated guess