Lesson 1 Flashcards
(36 cards)
How many annual deaths are attributable to alcohol abuse?
100,000; more than half of which are due to long-term use
How many annual deaths are attributable to smoking?
480,000
A pandemic is…
An epidemic occurring worldwide, crossing international boundaries and affecting a large number of people.
An epidemic…
Affects a disproportionately large number of individuals within a population at the same time in a population that was no prior exposure / immunity.
An endemic…
Refers to constant rates of infectious agents within a population.
R Naught
The number of infections you expect to see in other individuals from one infected person in a population w/o immunity.
A virus is…
An obligate intracellular parasite (infects cells because it cannot replicate on its own)
Viral genomes may contain…
RNA or DNA, but not both.
SARS-CoV
Severe Acute Respiratory Syndrome Coronavirus; circulated 2002-2004 following a spillover event from an animal host.
MERS
Middle East Respiratory Syndrome; emerged in 2012 and causes ongoing infection associated with spillover events from camel reservoirs.
Coronavirus Structure
- Corona = Crown
- Enveloped = Easier to kill
- Helical
- Largest single stranded RNA virus
- Proofreading RNA-dependent-RNA polymerase but not greatly efficient
Coronavirus spike proteins…
binds to ACE2 (angiotensin converting enzyme 2). ACE2 converts angiotensin II (vasoconstrictor) into angiotensin (vasodilator). Spiked glycoprotein allows the virus to be more detergent resistant and survive in the GI tract.
Inability to degrade ACE2 leads to…
localization of vasoconstriction –> raise in blood pressure, increased inflammation
TMPRSS2
Transmembrane serine protease; co-receptor; if the gene is deleted, virus cannot infiltrate the cell
3CL Protease
Cleaves translated polypeptide into individual proteins after auto-cleaving. Inhibition will stop reproduction of the virus.
ACE2 is expressed in the…
- Lung type II alveolar cells
- Enterocytes of the small intestine
- Arterial and venous endothelial cells
- Arterial smooth muscle cells
Anosmia and dysgeusia in COVID-19 may be caused by…
infection of the cortical neuron and glial involvement.
Zoonosis
Human infection acquired from animals
COVID-19 Life Cycle
1) Spike protein on virus binds to ACE2 and TMPSSR2
2) Virus enters cell via endocytosis, forming endosome
3) Virus released into cytoplasm and positive strand RNA is treated like mRNA –> translated into protein
RNA Dependent RNA Polymerases
Required by viruses to replicate; turns RNA into more RNA
Not present in humans, only have DNA dependent RNA polymerases (DNA –> RNA)
Low fidelity of RNA polymerases causes…
incorrect coding of amino acids, leading to different antigens –> new variants of the virus, unrecognized by the immune system.
Symptoms of COVID-19
Fever, chills, cough, dyspnea, anosmia, diarrhea, dysgusia, myalgias, weakness, headaches
Likely a very high number of asymptomatic infections.
Incubation of COVID-19
Mean incubation period started at 5-7 days, has since moved to 3-5 with new variants.
Time to hospitalization was 7-10 days, now 5-7.
Sudden Death from COVID-19
Likely a result of embolic events complication the clinical picture (PE, stroke, MI) also with myocarditis and CHF and arrhythmia.
