Question

A patient presents with flu-like symptoms. It is possible that the patient in fact has the flu, but another option is COVID-19 or even early stages of HIV. You have access to an advanced microscope where you are able to observe the morphology of the virions and their movement in and out of the cell. You also have access to assays that test for presence of viral enzymes. Using these methods only, how would you determine which of the three viruses the patient has been infected with?

Answer 1

I. Flu also known as Influenza

It enter into human body through the respiratory tract. Even a small dose of organisms can initiate the infection. The viscocity of the mucus te mucus fine linig of the respiratory tract and the surface of the cell exposed to viruse adsorption by the viral nuraminidase. It is a respiratory tract infection.

* Incubation period 1-3 days

* THe clinical symptoms fever,generalised myalgia and head ache.

* In the type B infection vomiting and abdominal pain in children. Also causes gastric Flu.

* Pneumonia is most important complication.

MORPHOLOGY:

* Spherical

* 80- 120 nm diameter

* pleomorphisms

* Filamentous form, seen through dark ground microscope, seen frequently in freshly isolated strain.

* Ribonucleoprotein ( helical symmetry) in virus core.

* Single strand RNA genome, segmented into 8 pieces

* Viral RNA- dependent RNA polymerase - In infected cell it causes transcription of viral RNA

* Necleocapisd surrounded by an envelop, outer lipid membrane ( from modofied host cell) and inner membrane protein ( M protein, M1 and M2)

* 2 types spikes ( peplomers) : hemagglutinin - triangle cross section

nuraminidase - mushroon shaped ( less in number)

Assays for the detection of viral enzyme

1. Complement fixation test: Detection of antibody

2. Hemagglutination inhibition: sensitive and convient

3. Enzyme nutralisation test for neuraminidase

II. COVID-19

Corona viruse is the infectious bronchitis virus. The incubatio period 2-5 after the common cold. It appears as second common cause of common cold. Thses causes seivere respiratory infection, with deep cough , difficult in breathing. Asymptomatic cases are also seen.

MORPHOLOGY:

* Spherical / Pleomorphic

* RNA virus

* Club shaped / Carrying petal shape peplomers on their surface.

*It mainly SARS - Severe Acute Respiratory Syndrome.

Assays

PCR- Polymerised Chain Reaction.

ELISA - Enzyme Linked Imunnosorbant Assay

HIV

The viruses entered into the body through blood or tissue or body fluid, mainly through the blood transfusion or physical contact. In the 3-6 weeks the infection being to appear with low grade fecer, nheadache, malaise and lymphadenopathy. Thses patient always suspected to any infection due to the low immunity.

MORPHOLOGY:

* spherical

* 90-120 nm in size

* nucleocaspid has inner cone shape core and outer icosahedral

* diploid. 2 identical stranded. positive sense RNA copies in th genome.

* reverse trancriptase enzyme

* envelop glycoprotein spike

* Transmembrane pedicle glycoprotein cause cell fusion.

Assays:

1. Antigen detection

2. Virus isolation

3. Polymerised Chain reaction

4. Antibody detection

a. ELISA tests

b. Western blotting

5. Serological test

a. Screening