E1 - VIROLOGY

44. What is another name for shingles?

Varicella zoster virus reactivation

17. What are oncogenic viruses?

Viruses are involved in cancers because they can either carry a copy of one of these genes or can alter expression of the cell's copy of one of these genes. These are the oncogenic virus (otherwise known as oncoviruses or tumor viruses).

5. What are the steps in viral replication?

Viruses are obligate intracellular parasites, meaning they must be inside a living cell in order to replicate. The first step is adhesion. The virus attaches to specific receptors on the surface of a susceptible cell by means of specialized structures on its surface, called adhesion molecules. The next step is penetration where the virus injects its genome. The final step is the assembly or maturation of the virus particles.

2. Describe the structure of a virus.

Viruses contain a viral genome of either RNA or DNA and a protein coat- the capsid. The genome and its protein coat together are referred to as a nucleocapsid. The entire virus particle is called a virion. Some viruses also have a phospholipid envelope surrounding the virion.

16. What time of year do most cases of influenza occur in the U.S.?

Winter time

12. What is antigenic drift?

A drift is caused by RNA replication errors of the virus. A drift is a minor change in antigenic structures mutations accumulate.

14. What diagnostic tests available for identifying influenza?

A number of commercial rapid kits are available for diagnosis of influenza in about 30 minutes. Influenza viruses can also be identified in the respiratory secretions by DFA, EIA, and optical immunoassays methods.

34. Which viruses are detected in still or rectal swabs?

Adenovirus, HSV, Mumps, VZV, Hepatitis.

19. Which type of swab should not be used for viral cultures because of potential toxicity to cell cultures?

Calcium alginate swabs inhibit the replication of some viruses and can interfere with nucleic acid amplification tests.

26. How are viruses grown in the laboratory?

Cell cultures can be divided into three categories: primary, low passage (or infinite), and continuous. Primary cell cultures, Finite cell line are diploid and continuous cell cultures are heteroploid.

35. Which viruses are detected in vesicular lesions of skin and mucous membranes?

Varicella Zoster virus

54. What laboratory tests are available for the diagnosis of SARS?

Electron microscopy, ELISA, and RT-PCR

45. Which virus causes infectious mononucleosis?

Epstein Barr virus

36. Which virus is detected by culture of blood?

HIV

38. Which virus is found in WBCs and cells of various organs and is transmitted by blood transfusions, organ transplants, and congenitally?

HIV/AIDS

33. Which viruses can be detected in urine?

HPV

47. Which virus is associated with genital warts and cervical carcinoma?

HPV-2

9. Name two retroviruses.

HTLV-1, HIV/AIDS

53. What is SARS?

It is known as sever acute respiratory syndrome, which is characterized by high fever, pneumonia, and in some patient's acute respiratory distress syndrome.

6. Which viruses are included in the family Herpesvirus?

Herpes simplex virus type 1(HSV-1) and 2 (HSV-2 or HHV-2) Varicella zoster virus (VZV or HHV-3) Epstein Barr virus- kissing disease (EBV or HHV-4) Cytomegalovirus-(CMV or HHV-5) Human herpes virus 6 (HHV-6) Human herpes virus 7 (HHV-7) Human herpes virus 8 (HHV-8)

46. Which virus is thought to cause Kaposi's sarcoma and some B-cell lymphomas?

Human Herpes virus 8

21. Which specimens should be obtained when aseptic meningitis due to an enterovirus is suspected?

If meningitis is suspected, naso-oropharyngeal swabs, rectal swabs, stool, cerebrospinal fluid, blood, and serum are collected and sent to the laboratory for testing.

37. Which age group is particularly susceptible to respiratory syncytial virus (RSV) bronchiolitis?

Infants & immunocompromised patients

56. Which viruses exhibit seasonal variation?

Influenza

55. Which virus cause avian flu?

Influenza A

8. Which of the following are RNA:

Influenza A, parainfluenza, mumps, measles, respiratory syncytial virus (RSV), rotavirus, human immunodeficiency virus.influenza A, , mumps, measles, respiratory syncytial virus (RSV), human immunodeficiency virus

57. For which viral infections is effective antiviral chemotherapy available?

Influenza, HSV-1, VZV,CMV and RSV

49. What does Sin Nombre Virus (SNV) cause?

It can cause fever, chills, myalgia, hypotensive shock and pulmonary edema.

11. How are influenza viruses unique?

It has the ability to change its antigenic structure in a major (hemagglutinin-H and neuraminidase-N) or minor way. The H antigen bins to host cells and neuraminidase cleaves budding viruses from infected cells. The Key to the persistence of the influenza virus if it antigenic variation.

22. What is the preferred specimen for detection of respiratory syncytial virus and influenza and parainfluenza viruses?

Nasopharyngeal secretions, aspirates or swabs, sputum, throat swabs, or bronchial specimens are collected.

23. What is the specimen of choice for detection of rhinovirus?

Nasopharyngeal swabs

57. What are the advantages of polymerase chain reaction (PCR) in the diagnosis of viral infections?

One of the advantages is that it is faster, and more specific and sensitive.

30. For viruses that cannot be grown in culture, what other laboratory methods may be used for diagnosis?

PCR, Nucleic acid hybridization tests, and EIA.

48. Which virus causes fifth disease?

Parvovirus B19 or erythema infectiosum

40. What is the major cause of viral respiratory disease in young children?

RSV

24. A specimen for viral culture is received in the lab at 12:00 P.M. The virologist is at a continuing education program and will not be back until 1:30 P.M. What should be done with the specimen?

They should be stored at 4 degrees Celsius.

43. What is another name for chicken pox?

Varicella zoster virus

7. Which virus causes chicken pox and shingles?

Varicella zoster virus (VZV or HHV-3)

4. What is the most common portal of entry for viruses?

Respiratory Tract

32. Which virus is the most common cause of gastroenteritis in infants, children, and the elderly?

Rotavirus

41. What is another name for measles?

Rubeola, Morbillivirus

42. What is another name for rubella?

Rubivirus, German measles

20. Name a transport medium for specimens for viral culture.

Several viral transport systems are available. Most media consist of buffered isotonic solution with some type of protein, such as albumin, gelatin, or serum, to protect less stable viruses. Antibacterial and antifungal agents are added in some transport systems to inhibit contaminating bacterial and fungal biota. Virocult, tryptose phosphate broth and in no transport medium.

25. A small microbiology laboratory only process specimens for viral culture on Fridays during the day shift. A specimen is submitted Friday evening and must be held for processing until the following Friday. What should be done with the specimen?

Should be frozen and held at 70 degrees Celsius

29. What are cytopathic effects (CPE)?

Some viruses produce characteristic cytopathic effects which provide a presumptive identification of a virus isolated from a clinical specimen.

13. What is antigenic shift?

Sometimes the surface antigens can change drastically causing an antigenic shift that can lead to pandemics, these results in new H or N antigen. There are two mechanisms of antigenic shift.one is genetic reassortment & the second is an adaptive mutation.

39. What is TORCH testing?

The TORCH screen is a group of blood tests that check for several different infections in a newborn. TORCH stands for toxoplasmosis, rubella, cytomegalovirus, herpes simplex, and HIV, but it can also include other newborn infections.

18. What is the optimum time to collect specimens for viral studies?

The best specimens are those collected as early as possible. The sensitivity of viral culture may decrease rapidly 3 days after the onset of symptoms.

31. What is the best method for diagnosis of rabies?

The fastest and most sensitive method of identifying rabies is by using direct IF techniques.

1. How do viruses differ from bacteria?

The main differences between the two organisms really relate more to their structure, size, and function. Bacteria are complex cells that have the ability to replicate, while viruses are about 100 times smaller, much simpler on a cellular level, and don't have the tools to replicate themselves. Viruses, which can be transmitted from hand-to-hand or mouth-to-mouth contact (the common cold) as well as sexually (HIV), need you in order to replicate. A virus works by invading one of your cells and hijacking it-essentially taking over its genetic code. They are obligate intracellular parasites. When the virus takes control of those healthy cells' replication machinery. Aside from lacking the ability to replicate themselves like bacteria, viruses have another weakness: in order for a virus to invade a cell, it needs some mode of transportation-it needs a chemical transporter to get to the cell. New therapies are focusing on blocking these transporters so viruses can't invade healthy cells.

10. In what way are retroviruses unique?

The retroviruses have a unique mode of replication; they require an RNA-dependent DNA polymerase to synthesize DNA from the RNA genome

27. Why are cell culture tubes placed on roller drums during incubation?

The roller drum provides motion that has been show to enhance the viral replication process

15. How accurate are the rapid antigen/ enzyme membrane test that are commonly used for the detection of influenza virus and RSV?

The sensitivity of these tests for influenza viruses and RSV are 10 to 85% and 50 to 98%.

28. What are shell vials and what is their advantage?

The shell vial culture technique is a simple method that more rapidly identifies viruses than the does the traditional cell culture method.

50. What is West Nile Virus (WNV)?

The west Nile virus is a single stranded RNA virus and a member of the Japanese encephalitis antigenic complex which is transmitted by a mosquito vector between birds and humans.

52. How is West Nile virus diagnosed?

They are diagnosed using IgG and IgM ELISA, including rapid WNV ELISA assays, and indirect immunofluorescent assay to screen for flavivirus.

3. What is a naked nucleocapsid?

They are viruses which lack an envelope.