Common cold, flu, and other respiratory disease-related viruses

Amaris Chen

Table of content

1. The pandemic
2. General knowledge about virus

a. viral structure and characteristics

b. quasispecies concept and viral mutation

3. The common cold

4. The influenza virus

5. Diagnosis and treatment of virulent diseases

Table of content

1. The pandemic
2. General knowledge about virus

a. viral structure and characteristics

b. quasispecies concept and viral mutation

3. The common cold

4. The influenza virus

5. Diagnosis and treatment of virulent diseases

The COVID-19

​

• COVID-19 (2019): 700,066,617 cases, 6,958,603 deaths, 671,338,160 revovered.

​

• People who had severe illness with COVID-19 might experience organ damage affecting the heart, kidneys, skin and brain
• In lungs, the air sacs can be filled with fluid leaking from tiny blood vessels in lungs, causing acute respiratory distress syndrome (ARDS), a form of lung failure.

magnetic resonance imaging (MRI) scan after xenon inhalation. Greater areas of darkness shows greater abnormality.

BBC. (n.d.). "Long Covid: Hidden lung damage spotted on scans - BBC News" [Photograph]. Retrieved from https://ichef.bbci.co.uk/news/976/cpsprodpb/1752E/production/_123043559_dac8c2fc-f6dd-4c13-885b-26ef778276a3.jpg

​

Social & economical impact

• Many countries (The US, European countries, China…) experienced recession due to lockdown, travel restrictions, and disruption in business.
• Unemployment surged due to inactivated market and bankrupcy
• Individuals suffer from financial and mental distress

The Spanish flu (1918-1920)

• The estimate number of deaths in this pandepic was 21 million, beyond the casualties of WWI.
• First developed in the US, the Spanish flu virus is said to come from those working closed to swines and fowls (cross species)

Everett/Shutterstock (n.d.).  [Photograph]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSfptmSOocpecjY280wQIcZ8AjrN0IUJ1MI9wz8ky58Mg&s

​

The purple death

• The first wave of 1918 pandemic was genarally mild: patients carry typical flu symptoms as chills, fever, and fatigue, while the number of reported death was low.
• The second wave was highly contagious. Victims died within hours or days of developing symptoms. Their skin turned blue and their lungs were filled with fluid, which suffocated them.

Table of content

1. The pandemic
2. General knowledge about virus

a. viral structure and characteristics

b. quasispecies concept and viral mutation

3. The common cold

4. The influenza virus

5. Diagnosis and treatment of virulent diseases

• What is virus?
• In what ways do they affect our health?
• What are characteristics of virus?

​

Table of content

1. The pandemic
2. General knowledge about virus

a. viral structure and characteristics

b. quasispecies concept and viral mutation

3. The common cold

4. The influenza virus

5. Diagnosis and treatment of virulent diseases

What is virus?

• An infectious, obligate intracellular parasite comprising genetic material (DNA or RNA) surrounded by a protein coat, sometimes a membrane

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTlvy6Q1GTi8zVhRuRHlROB3qMRm8itP5XinhhkQQo-ug&s

Different types of virus have different shapes

Tobacco mosaic virus

Adenovirus

Influenza virus

Bacteriophase T4

Campbell (n.d.). “Viral structure” [Image]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTlvy6Q1GTi8zVhRuRHlROB3qMRm8itP5XinhhkQQo-ug&s

​

Characteristics of living organisms

Unknown. (n.d.). [Characteristics of Living Things] [Image]. Retrieved from https://media.geeksforgeeks.org/wp-content/uploads/20230724124131/Characteristics-of-Living-things.png

Virus is an organism with two phases

Infectious particle

Infected (host) cell

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTdtq6yq85xtV6r2QTS1sYlA2jsjPk8QwZ7XPyll5ya-A&s

Table of content

1. The pandemic
2. General knowledge about virus

a. viral structure and characteristics

b. quasispecies concept and viral mutation

3. The common cold

4. The influenza virus

5. Diagnosis and treatment of virulent diseases

The quasispecies concept

“The genome of Qß cannot be described as a defined unique structure, but rather as a weighted average of a large number of different individual sequences."

E. Domingo, D. Sabo, T. Taniguchi, C. Weissmann. 1978. Nucleotide sequence heterogenity of an RNA phage population. Cell 13:735-744.

​

For a given RNA virus population, the genome sequences cluster around a consensus or average sequence, but virtually every genome can be different from one another.

The quasispecies concept

As a rare genome with mutations survive a selection event, other linked but unselected mutations take the free ride

​

New, diverse population emerged after replication

Unknown. (2009). [Quasispecies selection] [Image]. Retrieved from https://www.virology.ws/wp-content/uploads/2009/05/quasispecies-selection.jpg

• All mutations have error rate
• Low mutation rate is neither selective nor advantageous in nature
• Mutants are often less pathogenic under low mutations.

Unknown. (n.d.). [COVID-terminology-article] [Image]. Retrieved from https://www1.racgp.org.au/getattachment/newsGP/Clinical/What-s-the-difference-between-mutations-variants-a/COVID-terminology-article.jpg.aspx

The error threshold

The genetic bottleneck

The limited population (diversity) and rapid replication may accumulate the deleterious mutations

​

The progeny becomes less fit

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTomTdpOhL7ix7NXwoSCX9WQmgNmqZrho33vcEkvwOMkA&s

Real life example:

​

1.Small droplets of suspended virus during aerosal transmission

​

2. Activation of a latent virus from a limited population of cells

​

3.Small volume of inoculum introduced in infection by insect bites

The muller’s ratchet

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSKJrkGJYPfM6gmw9yMRNKzTu06r5IK-hlwJU4_1BtGrA&s

Solution: Exchange of genetic information

To sum up:

Diversity in a viral population is important for the survival of individual members

Table of content

1. The pandemic
2. General knowledge about virus

a. viral structure and characteristics

b. quasispecies concept and viral mutation

3. The common cold

4. The influenza virus

5. Diagnosis and treatment of virulent diseases

Why is common cold/influenza important?

The variants of their causative agents caused some of the world deadliest pandemics (COVID-19, Spanish flu, Asian flu, SARS pandemic)

​

High prevalance and global impact

​

High seasonal outbreaks and pandemic potencial

The Common Cold

1. Definition
2. Causative agents
3. Pathogenesis of rhinovirus
4. Viral replication
5. Symptoms
6. Bacterial complication
7. Transmission of virus
8. Prevention and treatments

The common cold

• Definition: A self-limited disease caused by viral infection of upper respiratory track

​

Pathogenesis of rhinovirus

• The virus deposits in the anterior nasal mucosa or in the eyes (get to nose through lacrimal duct)
• The viruses are transported to posterior nasopharynx by mucocilliary action

Unknown. (2020). [Throat Overview] [Image]. Retrieved from https://thancguide.org/wp-content/uploads/2020/01/04s-throat_overview-Artboard-1@2x.png

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcTCeo8VS-mAcAu4ATEK7ZZcfWP2b8urHlf6WzdYT9foQA&s

Replication

• In the adenoid area, the virus gains entrance to epithelial cells by binding to specific receptors (mostly ICAM-1) as their receptor.

​

• Once inside the cell, the virus begins its replication

​

• The virus sheds on the second day after inoculation

Symptoms

• There is a lack of epithelial destruction during rhinovirus infections, so symtoms are primarilly caused by inflammatory response of the host

Sore throat

Runny and stuffy nose

Sneezing

Coughing

Fatigue

Headache

fever

Bacterial complications

• In children, the most common complication is acute otitis media (occurs in 20% of children)

​

• Other common complications include sinuitis and pneumonia

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://media-us.amboss.com/media/thumbs/big_637c96a11e82b3.82653657.jpg

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQUR4x2LAeoMsTCsGWhAY62u-0UaFL6qtzcz2wN2nQHMg&s

National Heart, Lung, and Blood Institute (NHLBI). (n.d.). [Pneumonia] [Image]. Retrieved from https://www.nhlbi.nih.gov/sites/default/files/inline-images/pneumonia.png

�

​

How does the virus spread?

In infected host, the virus spreads mainly in respiratory droplets with several approaches:

​

1. Direct contact

2. airborn trasmission

3. Contaminated surface

4. close personal contact

5. poor hand hygiene

Treatments

• Due to the cold’s sel-limited and mild nature, vaccines are not necessities. Instead, patients may take treatments that alleviate the cold symptoms.

​

• To supress symptoms: Over-the-counter medications (Pain relievers, decongestants, cough suppressants and expectorants)
• To support immune system: sufficient intake of nutrients (Vitamin C is recommended), rest,

Table of content

1. The pandemic
2. General knowledge about virus

a. viral structure and characteristics

b. quasispecies concept and viral mutation

3. The common cold

4. The influenza virus

5. Diagnosis and treatment of virulent diseases

The influenza

1. Definition
2. Causative agents
3. Influenza A&B structure
4. Genetic drift and shift in inflenza virus
5. Symptoms

Influenza

• Definition: a highly contagious viral infection that primarily affects the respiratory system, attacking lungs, nose, and throat.

Influenza A & B virus

The hemaglutin (HA) facilitates viral entry

​

The neuraminidase (NA) facilitates viral release

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://media.springernature.com/m685/springer-static/image/art%3A10.1038%2Fs41572-018-0002-y/MediaObjects/41572_2018_2_Fig1_HTML.jpg

Influenza virus is capable of evading the antibody-mediated immunity induced during previous infections or vaccination by gradually accumulating mutations in HA and Na

​

antigenic drift of T cell epitopes has been observed but not as frequently as antibody-mediated drift

​

one or very few amino acid substitutions take place adjacent to the functional sites in the head (but not the stalk) of the HA protein

​

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRHK0AA6Q_AWcf9_6xmNMGt1_EdiLLWpPqp7f1Wx7_Ymg&s

drastic changes in the antigenicity of the HA of circulating influenza A viruses

​

molecules of pandemic viruses are derived from antigenically diverse animal strains of influenza virus, which can be acquired by human influenza strains through reassortment

​

Antigenic shift

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSuf60JPbxllepkDVdUqh8ZY-njrTuJJbD76Y_kibGTcg&s

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRHK0AA6Q_AWcf9_6xmNMGt1_EdiLLWpPqp7f1Wx7_Ymg&s

Pathogenisis of influenza A virus

The virus replication mainly takes place in epithelial cells of the respiratory tract in humans

​

The viral HA binds to sialic acids presents in the oligosaccharides of the glycoproteins at cellular surface, triggering a conformational change in HA that induces the fusion of viral envelope with that of endosome

Symptoms

The onset of flu is more sudden

​

The symptoms are more severe

Table of content

1. The pandemic
2. General knowledge about virus

a. viral structure and characteristics

b. quasispecies concept and viral mutation

3. The common cold

4. The influenza virus

5. Diagnosis and treatment of virulent diseases

Diagnosis and treatments

Diagnosis: virus culture

Virus is detected by the appearance of cytopathic effect

​

Advantage: high specificity

​

Disadvantage: slow (>3days)

​

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcQd43fQ4rEzhQFjZnHKxZonwAvF3ZmD0Swzun-PVdhNDg&s

Diagnosis:PCR (Polymerase chain reaction)

Unknown. (n.d.). [Polymerase chain reaction] [Image]. Retrieved from https://upload.wikimedia.org/wikipedia/commons/thumb/a/ab/Polymerase_chain_reaction-en.svg/1024px-Polymerase_chain_reaction-en.svg.png

RT-PCR: add one step

Advantage: High specificity, high sensitivity, moderately fast

​

​

Disadvantage: expensive, more prone to false positive results due to nucleic acid contamination

Preventions: pharmaceutical methods

Inactivated influenza A vaccine

​

Since 1970, the whole virus is now subjected to treatment with ether or detergent to make subvirion (or split) preparations, which are much less reactogenic and are more tolerable for the patient

​

mRNA vaccine

McGill University. (2022, June 8). [mRNA vaccine processing] [Image]. Retrieved from https://www.mcgill.ca/gci/files/gci/2022-06-08_mrna_vaccine_processing_1.png

�

​

Unknown. (n.d.). [Untitled image] [Image]. Retrieved from https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcRihRqSfrgnejMTjRUecZlTmEQObfrBZ8baPCZCBXxI4w&s

Thank you

Reference

1. Krammer, F., Smith, G.J.D., Fouchier, R.A.M., Peiris, M., Kedzierska, K., Doherty, P.C., Palese, P., Shaw, M.L., Treanor, J., Webster, R.G. and García-Sastre, A. (2018). Influenza. Nature Reviews Disease Primers, [online] 4(1). doi:https://doi.org/10.1038/s41572-018-0002-y.

2. Shi, Q., Xia, F., Wang, Q., Liao, F., Guo, Q., Xu, C. and Wang, J. (2022). Discovery and repurposing of artemisinin. Frontiers of Medicine, 16(1), pp.1–9. doi:https://doi.org/10.1007/s11684-021-0898-6.

3. Heikkinen, T. and Järvinen, A. (2003). The common cold. The Lancet, [online] 361(9351), pp.51–59. doi:https://doi.org/10.1016/s0140-6736(03)12162-9.

​

​