8.2 Emerging Viral Diseases Flashcards
List three animal reservoirs that have played an important role in recent emerging viruses and provide one viral example for each
- bird ,, avian influenza
- bat ,, Ebola virus
- rodent ,, hentavirus
List the factors affecting disease emergence
- microbial ,, altered virulence + evolution and adaptation
- social/behavioural ,, sexual behaviour, increased childcare centres + widespread business and leisure travel
- demographics ,, population growth (overcrowding and increase person to person contact) + urbanisation
- international travel and trade ,, one billion air passengers annually + mosquito transport
Changing ecosystems, economic development and land use, modern medicine, breakdown of public health measures + intent to harm
What are the primary and intermediate hosts that led to the emergence of SARS-CoV-1?
Primary host ,, bats
Intermediate host ,, civets
What mutation, in which viral protein, led to the SARS-CoV-1 emergence?
The spike (s) protein ,, it is hypothesised that palm civets act as an important intermediate for the transfer of SARS-CoV to humans which allows for the emergence of viruses with mutations at 479 and 487
What is the major difference between Bat SL-CoV-2 and Human SARS-CoV-1?
In comparison to Human SL-CoV, Bat SL-CoV uses a different (unidentified) receptor ,,
It is further hypothesised that intermediate (civet) SARS-CoV strains arose from the recombination between bat SL-CoV and another (animal) ACE2-binding CoV
What is the main reason for SARS-CoV-2 spreading greater than SARS-CoV-1
CoV-2 sheds and therefore spreads whilst a person is asymptomatic therefore leading to raid spread through a community whereas CoV-1 sheds only when a person is symptomatic.
Describe the replication cycle for SARS-CoV-2
It uses the genetic molecular ribonucleic acid, or RNA, to provide instructions to infected host cells to build more copies of the virus. A molecular cap on one end of the viral RNA serves multiple functions to accomplish this goal.
Why is it thought that the Pangolin is the intermediate host for SARS-CoV-2?
This guy an interacting arginine is conserved between SARS-CoV-2 and pangolin-CoV-2 and therefore displays a structural similarity in glycine binding between SARS-CoV-2 and pangolin-CoV-2020.
What were the effects of the D614G mutation for SARS-CoV-2?
The mutation is just outside of the RBD however increases the binding affinity for ACE2.
Is associated with three other mutations (Haplotype). Outside of the spike, one is silent.
Name the mutations in the RBD for the UK, South African and Brazilian variants. Which mutation seems to be the most important and why?
UK ,, N501Y (aspartame to tyrosine)
South African ,, N5017 + E484K (glutamine to lysine) + K417N (lysine to asparagine)
Brazilian ,, N501Y + E484K
The outbreak of the Chikungunya virus in the Indian Ocean was due to which vector? Which vector was associated with other outbreaks?
Aedes spp. (mosquito vector)
Ae Albopictus
Explain the effect of the E1-226 mutation in Chikungunya
Due to the widespread distribution of Ae. Albopictus, this mutation increases the potential for CHIKV to permanently extend its range into Europe, America and Australasian regions.
How was it shown that the E1-226 mutation occurred in mosquitoes?
Via three important observations ,,
- E1-226V genotype was dominant and appeared to be fitter than the E1-226A
- E1-226 mutation mediated efficient infection of Ae. Albopictus
- Major vector in Indian Ocean outbreak was Ae. Albopictus not Ae. Aegypti
This led researchers to test for fitness in different vector species
What is a micro evolution and how does it apply to the Chikungunya virus outbreak in 2005?
A micro evolution is genetic changes over a relatively short period of time within populations eg. The Indian Ocean outbreaks were of an unprecedented magnitude
