Diagnostics and Vaccines

Question 1

when is the highest number of viruses available for sample collection ?

Answer 1

during early stages of disease

Question 2

what is the gold standard for diagnosing viruses ?

Answer 2

virus isolation

Question 3

virus isolation

Answer 3

1) cell culture and CPE (serial dilution of virus samples in wells, where virus kills cells we have an infection)
2) viral quantitation (count plaques and perform calculation)
3) egg culture (add virus to an egg to see what happens, older technology)

Question 4

how do we know if a culture is infected in the lab?

Answer 4

TCID 50 : 50% of tissue is infected and show CPE at a certain viral dilution

Question 5

viral AG detection

Answer 5

• ELISA (only works if there is protein present, which means the virus is replicating)
• immunohistochemistry/ immunofluorescence

Question 6

viral nucleic acid detection

Answer 6

• done with PCR (denatue dsDNA, primer annealing, extension)
• the nucleic acids do not last long in the cell
• piece of diagnostic picture but cannot stand alone
• easy to contaminate, don’t trust positive results with the absence of lesions

Question 7

AB ditection

Answer 7

• ELISA

- viral neutralization (virus + patient serum, the more Ab present in serum the longer it will take for Ag to kill cell)

Question 8

virus visualization

Answer 8

-done with electron microscopy

Question 9

live vaccines

Answer 9

• more effective, less safe
• longer lasting immunity
• can be given by natural route
• disadvantage: reversion to virulence, spread

Question 10

what is an adjuvant ?

Answer 10

• used to enhance immunologic response to inactivated vaccines
• cause slower release of Ag and stimulate phagocytosis