Emerging + Re-emerging viruses Flashcards
define zoonotic disease (zoonosis)
- A zoonotic disease is a disease/infection that can be transmitted naturally from vertebrate animals to humans or vice versa
*Zoonotic diseases are amplified in an animal host where host isn’t dying from disease, virus gets chance to amplify which causes more mistakes/mutations/genome recombination so more chances for ability to infect humans
what is the life cycle of coronaviruses
*coronaviruses enter the cell through endocytosis
*enters the cytoplasm
*Coronaviruses (CoVs) are enveloped positive-sense RNA viruses [characterized by club-like spikes]
* CoV can make proteins immediately cuz CoV looks like mRNA it ‘tricks cell’
* it then exits through the golgi apparatus
* and is exocytosed and spread through body
which transmission is more contagious as it stays in air for longer
* airbone transmission
* droplet tranmission
airbone transmission; tiny patricles can be produced by talking/singing are suspended in the air longer and travel further, as opposed to droplet transmission from coughs/sneezes
define dyspnea, a symptom of SARS-CoV2. What other symptoms of SARS-CoV2 are there?
dyspnea= shortness of breath
*dry cough/ respiratory distress
*anosmia {loss of smell either partial or full}
*dysgeusia {a foul, salty, rancid, or metallic taste sensation persists in the mouth}
*fever
*altered mental status
explain:
*the viral replication phase n.b. which immunoglobulin is produced first?
*inflammatory phase
viral replication phase:
* at exposure there’s sudden increase of viral DNA (can last up to 2 weeks)
*then immune system response producing neutralising antibodies IgM first, then IgG
inflammatory phase
* Need correct therapeutics at right time
* Don’t want anti-inflammatory drugs at viral replication period, want to target virus but allow immune system to clear virus
what family of viruses does Influenza A belong to?
Influenza virus classification
* A/B/C influenza viruses
* Influenza A is Orthomyxoviridae family - enveloped virus with -ve sense genome, single-stranded, segmented RNA
* Only influenza A further classified by subtype based on 2 main surface glycoproteins HA/NA
explain the life cycle of an influenza A virus (IAV)
- IAV binds to target cell through interaction between sialylated receptors and HA/NA
- IAV envelope fuses with endosomal membrane under low pH, releasing viral genetic materials into cytosol
- Viral replication happens in nucleus and golgi apparatus
- Progeny virions are assembled, budded, and released from infected host cell to infect neighbouring cells
explain what we mean by
*antigenic drift
*antigenic shift
antigenic drift= slowly drifting mutations; these are minor changes to antigenic markers on the viruses
(Mutation rate highest for type A viruses, lowest for type C viruses,Most meaningful mutations occur in HA1 protein)
antigenic shift= rapidly emerging new mutations; these are dangerous + unpredictable
n.b. Phylogenetic evolution accounting for emergence of new virus strains
explain the replication cycle of HIV-1 (Human Immunodeficiency Virus)
- HIV doesn’t have cytoplasmic replication or reverse transcription - goes straight into nucleus (careful of textbook since this is new info!)
n.b. HIV usually requires both a CD4 + a chemokine {CXCR4/CCR5 aka fusin/CD184} receptor to infect target cells - Plasma membrane fusion - RNA released straight into nucleus then single stranded DNA made first followed by double-stranded DNA
- Then integrates into host genome
- Makes it hard to cure
- Viral genome transcribed and RNA exported, translated then proteins assemble and virus released
*it invades the dendritic cells which then go to the lymph nodes(through afferent lymphatic vessels) and now HIV contaminates the CD4+ CELLs attacking our immune system noe these CD4+ cells getting destroyed so smth small like flu/pneumonia will kill u as u have no immune system (i.e. normal commensal bacteria can even kill u that we usually live with fine)
