Virology 1

Question 1

How many known viruses are there and approx how many is unknown.

Answer 1

Approx 5000 known viruses
Probably thousands more as yet undiscovered

Question 2

define host range for viruses

Answer 2

the range of host organisms that a virus can infect

Question 3

Name the 4 types of shape visible in viruses under the microscope

Answer 3

○ Head and tail
○ Helix
○ Icosahedron
○ Variable(pleomorphic)

Question 4

Name examples of viruses where the 4 different types of shapes are visible in viruses under the microscope

Question 5

classification of viruses

Answer 5

Viruses can be classified based on molecular principles (Baltimore classification) or biological principles (International Committee on Taxonomy of Viruses system).

Question 6

structure of virions

Answer 6

Virions consist of a protein outer coat (capsid) and nucleic acid (DNA or RNA). Capsid proteins form regular structures called capsomers, which give the virus particle its symmetry.

Question 7

What is viral replication?

Answer 7

The process by which viruses produce more copies of their viral genome and viral proteins. Replication strategies vary depending on the type of virus (DNA, RNA, retrovirus).

Question 8

laboratory identification of viruses

Answer 8

Methods such as polymerase chain reaction (PCR) can be used to detect and analyze viral RNA sequences in samples. This helps determine the presence and type of virus.

Question 9

poliovirus

Answer 9

A virus that causes poliomyelitis, a disease characterized by flu-like symptoms and, in severe cases, paralysis. It is a vaccine-preventable disease.

Question 10

Herpes simplex virus

Answer 10

A virus that causes oral and genital herpes infections. It has an enveloped particle with a characteristic ‘fried egg’ appearance.

Question 11

influenza virus

Answer 11

A virus that causes seasonal flu. It has a variable, unstructured shape (‘pleomorphic’) and its particles are irregularly shaped and fused together.

Question 12

Norovirus

Answer 12

A virus that causes gastroenteritis (stomach flu). It is a non-enveloped virus with particles of around 110 nm in size.

Question 13

Echo Virus

Answer 13

A group of ‘orphan’ viruses that can cause unexplained illnesses. They are enteric cytopathogenic human orphan viruses.

Question 14

Monkeypox virus

Answer 14

A virus that causes monkeypox, a disease similar to smallpox. It has symmetrical particles of around 22 nm in diameter.

Question 15

SARS-CoV-2

Answer 15

The virus responsible for the COVID-19 pandemic. It is a novel coronavirus with symmetrical particles of around 22 nm in diameter.

Question 16

Nipah Virus

Answer 16

A virus that causes Nipah virus infection, a zoonotic disease. It has symmetrical particles of around 22 nm in diameter.

Question 17

head + tail

Answer 17

One of the four possible shapes of virus particles, characterized by a head containing nucleic acid and a tail that penetrates the host cell wall for DNA injection.

Question 18

helix

Answer 18

One of the four possible shapes of virus particles, characterized by a helical structure with nucleic acid wrapped around it.

Question 19

Icosahedron

Answer 19

One of the four possible shapes of virus particles, characterized by a helical structure with nucleic acid wrapped around it.

Question 20

Variable (Pleomorphic)

Answer 20

One of the four possible shapes of virus particles, characterized by an irregular and unstructured shape.

Question 21

Bacteriophage fX174

Answer 21

A virus with a head and tail structure. The head contains single-stranded DNA (ssDNA) and the tail penetrates the host cell wall for DNA injection.

Question 22

Tobacco Mosaic Virus

Answer 22

A helical virus with nucleic acid and glycoprotein capsid. It is approximately 18 X 300 nm in size.

Question 23

Polio virus

Answer 23

An icosahedral virus with capsid proteins arranged in an icosahedral form. It has four different glycoproteins: VP1, VP2, VP3, and VP4.

Question 24

Influenza virus

Answer 24

A variable, unstructured virus with irregularly shaped particles of 80-120 nm. The particles have fused membranes and contain haemagglutinin and neuraminidase glycoproteins.

Question 25

Herpes virus

Answer 25

An enveloped virus with a lipid envelope and a core virus particle containing double-stranded DNA. It has a characteristic ‘fried egg’ appearance.

Question 26

Escherichia coli

Answer 26

A bacterium that is approximately 1300 x 4000 nm in size.

Question 27

Poxviridae

Answer 27

A family of viruses, including the smallpox virus, that are approximately 300 x 240 x 100 nm in size.

Question 28

Herpesviridae

Answer 28

A family of viruses, including the herpes simplex virus, that are approximately 120-200 nm in size and have an envelope.

Question 29

Bacteriophage - T4

Answer 29

A bacteriophage virus with a diameter of 200 nm.

Question 30

Picornaviridae

Answer 30

A family of viruses, including the polio virus, that have a diameter of 22 nm.

Question 31

capsid

Answer 31

The protein outer coat of a virus particle.

Question 32

Nucleic acid

Answer 32

The genetic material (DNA or RNA) of a virus.

Question 33

nucleocapsid

Answer 33

The combination of nucleic acid and protein in a virus particle.

Question 34

Viral reverse transcriptase

Answer 34

An enzyme used by retroviruses to convert their RNA genome into DNA, which is then integrated into the host genome

Question 35

Positive sense single stranded RNA virus

Answer 35

A virus with a single-stranded RNA genome that can act as mRNA inside the host cell.

Question 36

Negative sense single-stranded RNA virus

Answer 36

A virus with a single-stranded RNA genome that needs to be copied into a positive sense RNA before it can act as mRNA inside the host

Question 37

Double-stranded RNA virus

Answer 37

A virus with a double-stranded RNA genome that can be transcribed into viral mRNA by viral RNA polymerase.