diagnosis of viruses

Question 1

symptomology clinical categories

Answer 1

Jaundice, febrile polyarthritis, haemorrhagic fevers, SARI, encaphalitis, meningitis, rash, diarrhea, arboviruses, rodent feacal-oral

Question 2

jaundice

Answer 2

Hep A - E and G. Yellow fever. Human cirrhosis virus (unclassified)

Question 3

Febrile polyarthritis

Answer 3

(joint inflammation + fever) Dengue virus, ross river virus, O’nyong’nyong virus, Chikungunya virus

Question 4

Haemorrhagic fevers

Answer 4

Yellow fever, Lass/Tacharibe viruses, Crimean-congo/Dugbe viruses, Ebola and Marburg virus

Question 5

Severe acute respiratory infections

Answer 5

Influenza, SARS/MERS, Hantavirus, Adenovirus 14, Nipah/Hendra virus

Question 6

Encaphalitis/meningitis

Answer 6

Cyclovirus Vietnam, West Nile virus, Tick-borne encephalitis virus, Lymphatic choriomeningitis virus, Rabies, Thogotoviruses

Question 7

Rash

Answer 7

Herpes, roseolavirus, HPV, smallpox/cowpox, dengue fever, ross river virus, rubella, measles, hand-foot-mouth disease, erythrovirus,

Question 8

Diarrhea

Answer 8

Noroviruses, rotaviruses, hand-foot and mouth disease

Question 9

Arboviruses

Answer 9

Flaviviruses -> West nile, dengue, tick-borne encephalitis, yellow fever
Togaviridae -> all except rubella
Bunyavirdae -> dugbe, rift valley fever, crimean congo haemorrhagic fever
Orhtomyxoviridae -> dhori virus, thogoto virus

Question 10

Rodent faecal-oral

Answer 10

Arenaviridae -> lassa viruses
Bunyaviridae -> hantavirus

Question 11

Functional technique - Pfu

Answer 11

plaque forming units - quantifies the presence of a virus

Question 12

Functional technique - haemagglutinin inhibition assay

Answer 12

serial dilution of virus added to wells and RBC’s added. The more virus is present, the greater the degree of agglutination

Question 13

COVID-19 diagnosis through PCR

Answer 13

nasopharyngeal swab is collected
RNA is extracted from the deactivated virus
purified RNA is reverse transcribed to DNA and amplified by PCR
Positive patients cross the threshold line within 40,000 cycles (flourescence shows)

Question 14

COVID-19 diagnosis through serologic test (lateral flow assay)

Answer 14

sample added to well with dilution phosphate saline solution
antibodies with specificity for COVID-19 bind to gold covid19 antigen coagulates in conjugate pad
sample enters testing well and covid-19 A-A complex binds to immobilised anti-human IgG/IgM antibodies on test strip
Rabbit antibody gold conjugate binds to immoblised anti-rabbit IgG antibodies on control strip

Question 15

Sandwich ELISA

Answer 15

Quantifies presence of viral proteins antibody A at the bottom of the well - specific for antigen of virus being tested
test sample is added and any antigen binds to the antibody
everything washed
antibody B is added and binds to antigen being tested for
excess washed away
an enzyme conjugated secondary antiobdy is added - specificity for Ig from species of anitobdy B. binds only if antiobdy B is bound
chromogenic substrate of the enzyme is added and colour intesity after a fixed period of time determines the result of the test

Question 16

Antibody capture ELISA

Answer 16

Quantifies presence of antibodies to a virus
Well is coated with a viral antigen
Test samples are added to the wells in serial dilutions
the unbound Ig is washed away and any antibody is detected by addition of a secondary antibody which is enzyme coupled
A positive result is detected by the enzyme converting the substrate into a coloured product

Question 17

Neutralisation assay

Answer 17

Quantifies presence of functional antibodies to a virus