COVID-19 (5.2) Flashcards
What does a virion contain?
Each virion, or viral particle, contains the minimum equipment to allow it to replicate: a protective outer layer (envelope) and its genetic blueprint (genome).
True or false: are viruses alive?
False: Viruses are not living bc:
- They are not made out of cells
- Don’t grow
- Cannot make their own energy
True or false: A common cold id caused by a large number of different viruses
True
True or false: viruses can not transfer between animals and humans?
False:
There has been evidence of viruses originating in birds, pigs, bats and other animals that mutated to become dangerous to humans
Viruses:
- Come in all shapes and sized
- Contain single-stranded or double-stranded DNA or RNA
- Surrounded by a capsid or a protein coat -> contains viral proteins that allow it to interact with receptor proteins on the host cells -> these allow the virus to attach to the cell and enter it
- Have an outer envelope derived from the membrane of their host
They MUST replicate inside the host cell to cause an infection disease
Viral life cycle:
- Viral attachment to a host receptor protein -> which gives them access to the inside of the cell
Every virus has a different mechanism for entering the cell, uncoating and synthesizing its genome, translating viral proteins and assembling into virions. BUT ALL VIRUSES require the host cell machinery to replicate.- Once virions are assembled, each virus utilizes a particular process to release them into the extracellular envirm -> they go to infect more cells.
What is the difference between SARS and COVID?
The diseases that are caused by viruses often have different names than the viruses themselves. For example, both COVID-19 and SARS (Sudden Acute Respiratory Syndrome) are caused by coronaviruses. The virus that causes SARS was first identified in 2003 and named SARS-CoV, while the virus that causes COVID-19 is known as SARS-CoV-2.
What is the difference between a pandemic and an epidemic?
Epidemic: A widespread occurrence of infectious disease in a community for a period of time.
Pandemic: A widespread occurrence of infectious disease worldwide, or over a large area, for a period of time.
1918 influenza?
- Several waves (e second wave being especially lethal)
- The virus spread in three waves, until eventually evolving into the annual influenza seasons found worldwide today.
- Little was unknown about the disease so it was difficult to manage.
- The origins of the virus are still unknown
- Death were common in young healthy adults (20-45 yo)
- Current theories suspect that an overactive inflammatory immune response in young adults lead to secondary pneumonia and tissue damage, ultimately leading to death
- Movement of the troops brought the virus
- No quarantine
- Prohibition of public gatherings and isolating the sick -> didn’t work
- There were no social safety nets, and medical treatment was available for only those who could afford it.
- Many had to work through illnesses so they could keep their jobs and afford food and rent
- Many children forced to leave school to work
- In the winters, many people froze to death if they were unable to cut firewood and maintain their fires for heat
Deaths among Indigenous people were higher than among non-Indigenous people
What happen in response to the 1918 pandemic?
In response to the crisis, the federal government founded the Department of Health in 1919. This helped lay the groundwork for managing the next pandemic 100 years later
How did some communities evade the 1918 virus?
Shishmaref, an island community north of the Bering Strait, halted the virus by stationing guards a few miles south. They were ordered to not allow anyone in or out during the outbreak, protecting the village and other communities in Northern Alaska and Arctic Canada.
Compare COVID and 1918
- Both were caused by novel virus: both viruses that humans had not seen before, and consequently, had no established immunity against.
- Unrelated viruses
- Sudden onset
- Multiple wave and mutations
- Overwhelmed healthcare system
Deadly results
COVID
- New vaccine development
- Deploy medical treatments and technology
- Modern infectious control and public health practices
Vaccine strategies in Ontario and the rest of Canada have been implemented to protect frontline healthcare workers and the most vulnerable and at-risk people. This included beginning with individuals in long-term care homes as well as Indigenous Peoples, especially those on reserves and remote communities. As the elderly are most susceptible, the general population was given priority by descending age
Symptoms of covid:
fever, cough, and fatigue
In many mild cases, patients develop a loss of sense of smell and taste.
“Brain fog” has been reported in some patients, which persists for months after infection is cleared.
Coronavirus family:
- Spherical
- Enveloped
- Single-stranded RNA genomes
SARS-CoV-2 virus contains special proteins known as spike proteins
Mechanism of infection of COVID?
- Entry: Virions enter the body and travel to the lungs through the oral (mouth) or nasal passage (nose).
- Attachment: SARS-CoV-2 particles can then enter cells in the lungs by attaching to receptors known as A C E 2. More specifically, it is the spike protein found on SARS-CoV-2, that binds to A C E 2 receptors. This binding is the lock and key that allows the virus to gain entry into the cell.
- Replication: The virus hijacks the machinery of the host cell to replicate itself.
- Release: New SARS-CoV-2 virions bud out of the host cell.
- Infection: These virions proceed to infect other tissues in the body. They may also infect other people or organisms if they are expelled from the host (e.g., by coughing or sneezing).
Why does COVID have a such wide variety of symptoms?
SARS-CoV-2 is able to infect a wide variety of cells (and tissues) because many human cell types have A C E 2 receptors. This is likely the reason why COVID-19 presents with such a broad range of symptoms
How does SARS enter the body?
The spike protein undergoes a shape change when it binds to the ACE-2 receptor, which then allows a protease to cut it and activate its ability to fuse the virus to the host cell membrane
SARS-CoV-2 requires a host to replicate. It spreads from host to host via droplets and aerosols, and does not survive long on surfaces
Measure to stop the spread of COVID?
- Distancing Social: distancing of at least 2 meters between individuals.
- Closures: Closing areas and activities that allow close contact with large numbers.
- Masking Wearing: face masks and shields, to prevent person-to-person transfer.
- Washing: Handwashing, hand sanitizing, and cleaning commonly touched surfaces.
- Staying :Stay-at-home orders to prevent community spread.
- Quarantining: Quarantining travelers and individuals with symptoms or close contacts.
Tracing: keeping track of infected persons and their close contacts
First problems with testing early in the pandemic:
We had basically three challenges. The challenge was that we didn’t have enough staffing to do the testing. We didn’t have the, enough equipment or even some of the essential equipment in place to do the testing. And then what became very apparent was we did not have the disposables that the petri place, the petri dishes, the tips for pipettes, none of those were available
Types of vaccines:
Viral vector, mRNA, whole virus, protein subunit, virus like particles
(Vaccine) Viral vector:
use of an unrelated, harmless virus to deliver the gene sequence for a protein virus of interest> The viral vector used in these types of COVID-19 are adenoviruses that encode the SARS-CoV-2 spike protein. EXEMPLE: : AstraZeneca: Vaxzevria, Janssen (Johnson & Johnson): Ad26.COV2.S
(Vaccine) mRNA
contains a synthetic portion of an mRNA that codes for a piece of a protein found in the virus -> covid: mRNA that codes for a harmless piece of spike protein. EXEMPLE: Pfizer-BioNTech: Comirnaty, Moderna: Spikevax
(Vaccine) whole virus
contains a live attenuated (weakened) or inactivated (killed) version of the virus. Covid: , the vaccine contains inactivated SARS-CoV-2 viral particles to expose the body’s immune system to the virus without risking a serious disease response. EXEMPLE: Sinovac: CoronaVac, Bharat Biotech: Covaxin
