Virus 1

Question 2

What are the characteristics of medically important DNA viruses and prions?

Answer 2

Based on morphology, host, mode of transmission, and the diseases caused.

Question 3

What is the classification basis for viruses?

Answer 3

Based on nucleic acid and the capsid (its size and symmetry and whether it is enveloped).

Question 4

What type of parasites are viruses?

Answer 4

Obligate intracellular parasites.

Question 5

Are all DNA viruses double-stranded?

Answer 5

No, all DNA viruses are double-stranded except parvoviruses, which have ssDNA.

Question 6

Are all RNA viruses single-stranded?

Answer 6

No, all RNA viruses are single-stranded except for dsRNA reoviruses.

Question 7

What virus causes smallpox?

Answer 7

Variola virus.

Question 8

When was smallpox declared eradicated by WHO?

Answer 8

1980.

Question 9

What are the two types of variola virus?

Answer 9

• Variola major - fatal disease
• Variola minor - mild disease.

Question 10

What is the portal of entry for variola virus?

Answer 10

The mucous membranes of the upper respiratory tract.

Question 11

What are the stages of clinical findings in smallpox?

Answer 11

• 1-5 days of fever and malaise
• Exanthems: macules, papules, vesicles, pustules.

Question 12

What is the case fatality rate for smallpox?

Answer 12

Varies from 5% to 40%.

Question 13

What chemotherapeutic agent was used against pox viruses?

Answer 13

Methisazone.

Question 14

What virus causes molluscum contagiosum?

Answer 14

Molluscipox virus.

Question 15

What are the symptoms of molluscum contagiosum?

Answer 15

Small, pink, wart-like tumors on the face, arms, back, and buttocks.

Question 16

How is molluscum contagiosum spread?

Answer 16

By direct and indirect contact.

Question 17

What are the routes of transmission for Herpes Simplex Virus (HSV)?

Answer 17

• HSV-1: Respiratory droplets or infected saliva
• HSV-2: Genital routes, sexual contact.

Question 18

What is the primary lesion of oropharyngeal disease caused by HSV?

Answer 18

Gingivostomatitis.

Question 19

What characterizes genital herpes?

Answer 19

Vesicular lesions of the penis in males, vulva, vagina, and perineum in females.

Question 20

What is the mortality rate for neonatal herpes?

Answer 20

50%.

Question 21

What is the treatment for herpes infections?

Answer 21

Acyclovir, Valacyclovir, and Vidarabine.

Question 22

What causes varicella (chickenpox) and zoster (shingles)?

Answer 22

Varicella-Zoster virus.

Question 23

What are the earliest symptoms of varicella?

Answer 23

Malaise and fever.

Question 24

What are the complications associated with zoster?

Answer 24

Postherpetic neuralgia and pneumonia.

Question 25

What virus leads to congenital anomalies and infectious mononucleosis?

Answer 25

Cytomegalovirus (CMV).

Question 26

What are the clinical findings in normal hosts infected with CMV?

Answer 26

Exudative pharyngitis, malaise, myalgia, protracted fever, liver function abnormalities, lymphocytosis.

Question 27

What is Burkitt’s lymphoma associated with?

Answer 27

Epstein-Barr virus (EBV).

Question 28

What is the treatment for Burkitt’s lymphoma?

Answer 28

Rituximab and chemotherapy.

Question 29

What does Human Herpes virus 8 cause?

Answer 29

Kaposi’s sarcoma.

Question 30

What is the primary mode of transmission for Hepatitis B virus (HBV)?

Answer 30

Parenterally/percutaneously, sexually, and vertically/perinatally.

Question 31

What is the incubation period for acute Hepatitis B?

Answer 31

30-180 days.

Question 32

What are the symptoms of acute Hepatitis B?

Answer 32

* Myalgia * Malaise * Nausea * Fatigue * Abdominal pain * Jaundice.

Question 33

What is the most common type of minor salivary gland malignancy?

Answer 33

Mucoepidermoid carcinoma.

Question 34

What virus causes warts?

Answer 34

Human Papillomavirus (HPV).

Question 35

What are the types of warts caused by HPV?

Answer 35

* Common seed warts * Plantar warts * Genital warts.

Question 36

What is the treatment for genital warts?

Answer 36

* Cryotherapy * Laser therapy * Electrosurgery * Surgery.

Question 37

What is the only known parvovirus pathogenic for humans?

Answer 37

B19.

Question 38

What is the most common manifestation of human parvovirus infection?

Answer 38

Erythema infectiosum (fifth disease).

Question 39

What is the mode of transmission for parvovirus B19?

Answer 39

Through respiratory droplets and fomites.

Question 40

What laboratory diagnosis method is most sensitive for parvovirus B19?

Answer 40

Polymerase chain reaction.

Question 41

What types of diseases can adenoviruses cause?

Answer 41

Diseases in the respiratory, gastrointestinal, urinary tracts, and in the eye.

Question 42

How many serotypes do human adenoviruses have?

Answer 42

Nearly 51 serotypes.

Question 43

What is the main method for transfusion therapy?

Answer 43

Transfusion therapy may be required for certain conditions.

Question 44

What do commercial immunoglobulin preparations contain?

Answer 44

Neutralizing antibodies to human parvovirus.

Question 45

Is there a vaccine against human parvovirus?

Answer 45

No.

Question 46

In which tracts can adenoviruses replicate and produce disease?

Answer 46

Respiratory, gastrointestinal, urinary tracts, and the eye.

Question 47

How many groups and serotypes do human adenoviruses have?

Answer 47

Six groups (A–F) and nearly 51 serotypes.

Question 48

Can a single adenovirus serotype cause different clinical diseases?

Answer 48

Yes.

Question 49

What is a common outcome of eye infections caused by adenoviruses?

Answer 49

Complete recovery with no lasting sequelae.

Question 50

What is epidemic keratoconjunctivitis?

Answer 50

A serious, highly contagious disease mainly occurring in adults.

Question 51

What percentage of pneumonias in childhood are caused by adenoviruses?

Answer 51

About 10–20%.

Question 52

What is the mortality rate of pneumonia in the very young caused by adenoviruses?

Answer 52

8–10%.

Question 53

What gastrointestinal disease is associated with adenoviruses?

Answer 53

Infantile gastroenteritis.

Question 54

What is the mechanism of oncogenesis for DNA oncoviruses?

Answer 54

Transform infected cells by integrating their DNA into the host cell’s genome.

Question 55

What are the roles of Rb and p53 in cancer?

Answer 55

They regulate the cell cycle.

Question 56

Which virus is associated with cervical cancer?

Answer 56

Human papilloma virus (HPV).

Question 57

What cancer is associated with HHV-8?

Answer 57

Kaposi's sarcoma.

Question 58

What cancers are associated with Epstein–Barr virus?

Answer 58

Nasopharyngeal carcinoma, Burkitt’s lymphoma.

Question 59

What cancer is associated with cytomegalovirus?

Answer 59

Mucoepidermoid carcinoma.

Question 60

What is a prion?

Answer 60

A proteinaceous infectious agent.

Question 61

What is the incidence of all human prion diseases?

Answer 61

1 in 1,000,000.

Question 62

Name a human prion disease.

Answer 62

Creutzfeldt-Jakob disease (CJD).

Question 63

What are the causes of prion disease?

Answer 63

Acquired, genetic, sporadic.

Question 64

What are the clinical features of prion diseases?

Answer 64

Loss of motor control, progressive dementia, paralysis, and wasting.

Question 65

What unique change occurs in neurons due to prion diseases?

Answer 65

Large vacuoles can form, leading to spongiform changes.

Question 66

How do prions differ from viruses?

Answer 66

Prions are protein molecules with no nucleic acid; viruses have nucleic acids packed in a protein capsid.

Question 67

Why are prions nonimmunogenic?

Answer 67

Normal protein PrP^C renders the host tolerant to PrP^Sc.

Question 68

What is the difference in structure between PrP^C and PrP^Sc?

Answer 68

PrP^C has a predominantly α-helical structure, while PrP^Sc has high β-sheet content.

Question 69

What therapeutic approaches have shown limited effects in prion disorders?

Answer 69

Polyene antibiotics, dextran sulfate, and β-sheet breaker peptides.

Question 70

What is the WHO recommendation for sterilizing surgical instruments contaminated with prions?

Answer 70

Immerse in 1N sodium hydroxide and autoclave at 121 °C for 30 minutes.

Question 71

Fill in the blank: PrP^C contains 40% _______ and little β-sheet.

Answer 71

α-helix

Question 72

Fill in the blank: PrP^Sc contains 30% α-helix and _______ β-sheet.

Answer 72

45%