Overview principles Of Viral Infection

Question 1

Essential components of a virus

Answer 1

DNA/RNA (NEVER BOTH)
capsid core
Polymerase protein

Question 2

Non essential part of protein

Answer 2

Envelope

Question 3

Characteristics of viruses used for classification

Answer 3

Type of acid (dna/rna)

Presence of lipid envelope

Symmetry of nucleocapsid

Number of strands of nucleic acid

Polarity of viral genome

Question 4

Adenovirus is

Answer 4

Spread by GI or respiratory route

Question 5

Cell functions required for viral propagation

Answer 5

Machinery for translation of viral mRNAs

Enzymes for replication of genome and assembly of new virions

Transport pathways to reach the sites of replication, viral assembly

Energy source

Question 6

Types of capsid symmetry

Answer 6

Icosahedral
Helical
Complex

Question 7

Envelope on virus decides what

Answer 7

Non enveloped viruses are stable in environment (transmitted by food or water)

Enveloped viruses - only survive transiently outside the host

Question 8

Viral surface proteins do what

Answer 8

Attach to membrane proteins in host cell

Target for antibodies

Determinants of antibody specificity

Question 9

Viral protein synthesis is completely dependent on

Answer 9

Cellular translation machinery

All viral genomes must produce MRNA to express viral proteins

Question 10

Stages of infections disease progression

Answer 10

Incubation

Prodrome

Illness

Recovery

Question 11

Imcubation

Answer 11

Time between exposure and onset of specific sign

Question 12

Prodrome

Answer 12

Nonspecific constitutional symptoms occur

Not all infections have prodromol stage

Question 13

Illness

Answer 13

Period in which clinical features of the infection manifests

Question 14

Types of infection

Answer 14

Superficial

Systemic

Question 15

Superficial infection is

Answer 15

Self limiting, microorganisms replicate in the epithelium at the site of entry and local damage caused

Question 16

Systemic entry is

Answer 16

Replication of microorganism at multiple sites.

Infection of deeper tissues

Spread in body through lymph or blood

Question 17

Acute infection

Answer 17

Rapid onset with brief period of symptoms

Usually cleared in days

Question 18

Persistent infection

Answer 18

Pathogen not cleared the host following primary infection

Remains in tissues

Question 19

2 types of persistent infection

Answer 19

Latent - microorganism persists after initial clearance .
Can be symptomatic or asymptomatic on reactivation

Chronic: continued production of the infectious organism and immune evasion

Infected hosts are carriers

Question 20

Types of viral infections based on occurrence

Answer 20

Sporadic- occasionally

Endemic- continuously present in a population (hiv)

Epidemic- greater number of cases than normal in short period of time in area

Pandemic- epidemic disease but worldwide

Question 21

Nosocomial infections.

Answer 21

Any infection acquired in hospital or medical facility

Question 22

Common nosocomial infections

Answer 22

Influenza 
Onto iris
Rsv
Chickenpox
Measles 

Transmitted easily, can’t always. Be prevented by proper hand washing

Question 23

Determinants of pathogenisis: host

Answer 23

Age
Underlying characteristics 
Genetic variation
Immunodeficiency 
Immune response 
Trauma/surgery

Question 24

Diagnostic virology

2 ways to test for virus

Answer 24

Direct tests presence

Indirect tests response

Question 25

Determinants of pathogenisis: tropism

Answer 25

Host range: refers to different species of host a given pathogen can infect Tissue tropism- tissues than can be infected by pathogen. Depends on the attachment A permissive cells allows a pathogen to replicate. Lacks defence against pathogen

Question 26

Pathogenicity is

Answer 26

Ability of microbe to cause disease

Question 27

Virulence is

Answer 27

The level of pathogenicity in an microorganism

Question 28

Virulence depends on?

Answer 28

Tropism Invasiveness Production of factors that increase toxicity

Question 29

Difference between lethal dose and infectious dose

Answer 29

LD50- lethal dose- number of pathogens that kill 50% of an experimental group of hosts Infectious dose ID50- number of pathogens that infect 50% of experimental group of hosts

Question 30

Super antigens are

Answer 30

Toxins that stimulate the immune system Can bind to MHC II and stimulate many T cells

Question 31

Viral DNA / RNA detected how

Answer 31

NAAT A Nucleic acid amplification technique (pcr)

Question 32

What do you do to detect RNA viruses

Answer 32

Use reverse transcriptase to mak e DNA then dna is identified

Question 33

Serological techniques

Answer 33

Add antigen to patient serum If binding occurs then virus present

Question 34

What’s used. to inference acute infection

Answer 34

IGM first

Question 35

Control of viral infections

Answer 35

Public health Immunisations Antiviral therapies

Question 36

Classification of polymerase inhibitors

Answer 36

By nucleic targeta DNA polymerase RNA polymerase Reverse transcriptase By chemical structure Nucleoside inhibitors Nucleotide inhibitors Non nucleoside inhibitors

Question 37

Adaptive immunisation types

Answer 37

Passive | Active

Question 38

Active adaptive immunity

Answer 38

Exposure to infectious antibody or vaccination