introduction to virology Flashcards
what’s Pro-MED? what benefit did this initiative bring?
program for monitoring emerging diseases
they promote communication amongst the international infectious disease community
in December 2019, the Wuhan Municipal community issues an urgent notice on the treatment of pneumonia of unknown cause – COVID 19, which will soon quickly spread the world due to its contagious properties
describe measles
a highly infectious disease, resulting in the easy spread in large groups with an infected person
it can be transmitted in aerosols thru cough and sneezes
it has become less prevalent in Canada due to vaccination, some won’t vaccinate in fear of side effects
94% of infected individuals were unvaccinated
still a major problem in certain parts of south america and africa
describe the H1N1 influenza outbreak in Alberta
resulted in 10 deaths
infected all age groups
there was concern for families of infected individuals who had older family members
where did the 2014 Ebola outbreak occur?
in Guinea, Liberia, and Sierra Leone
describe the Zika virus
links to microcephaly, a birth defect where a baby’s head is smaller than expected - often has smaller brains that might not have developed properly
if an expecting mother is infected with this virus, it can cause infants to be born with microcephaly – or other congenital malformations, preterm birth, miscarriage
what are endogenous retroviruses?
e.g. HERVs
“junk DNA” or “fossil records” of ancestral retrovirus invasions
- remnants from infections that occurred millions of years ago but are no longer infectious
they can be transcriptionally active and critical for human development and health – they are dormant (temporally inactive) but can be reactivated by several stimuli such as sickness, stress, and etc.
what are exogenous retroviruses?
e.g. IV
infectious RNA/DNA containing viruses that are transmitted from one organism to another, aka active
what are the levels of defense mechanism?
physical barrier
- skin and mucous of the digestive/respiratory tract
- helps eliminate pathogens and prevents tissues and/or blood infections
innate immunity
- involves immune cells and proteins to non-specifically recognize and eliminate any pathogens that enter the body
acquired immunity
- aims to eliminate specific pathogens which have been encountered by the immune system previously
note that most viruses that infect us do not cause disease
describe an example of how viruses can be beneficial to the host (wasps & eggs)
wasps lays their eggs inside a living insect larva
when female wasp deposits eggs inside a caterpillar, she also deposits her polydnavirus virus genome sequence
the innate immune system of larve would normally kill the egg, preventing its development….
but elements of the polydnavirus virus genome expressed by the wasp suppresses the innate immune response, allowing the survival and growth of the wasp egg
describe an example of how viruses can be beneficial to the host (fungus growth)
fungus cannot grow when temperature is greater than 50 degrees
fungal thermotolerance is mediated by the curvularia thermal tolerance virus (CThTV)
the fungus forms a symbiotic relationship with the dichanthelium lanuginosum (plant) which also allows the plant to grow in hot temperatures
describe an example of how viruses can be beneficial to the host (appearance of tulips)
“tulipomania” the first documented economic crisis
Holland in the 1600s experienced an economic upswing - freedom from space
the Bubonic plage killed thousands but this resulted in increased wages in survivors who wanted to purchase “luxuries”
the Dutch would spend 3000 guilders for a single bulb believed to produce the rare and beautiful broken tulip (a tulip that had two colours)
tulips were purchases in advance with the promise of breaking a highly speculative market
- by the mid 1600s, the tulip market crashed, leaving many bankrupt
the study of virology determined that a potyvirus (positive-strand RNA virus), Tulip Breaking Virus (TBV) results in the pattern
- TBV interferes with the synthesis of pigments in the flowers
- TBV is an elongated virus type
describe the importance of the genome for viruses
in order for viruses to survive, they must package their genome inside a particle and then use this particle to transfer their genome, from host to host
the genome contains information to initiate and complete the viral infectious cycle
genomes establish themselves in host ensuring long term viral survival
when was it determined that genomes were the key to viruses?
around the 1950s
why are viruses considered obligate parasites?
they can only function after they replicate in a host cell
viruses must make a mRNA that can be translated by host ribosomes to make viral proteins
no virus can translate proteins from mRNA on their own! - viruses do not have ribosomes of their own
they even use the host cell’s energy and transport vesicles
most viruses do not kill their host, why?
if viruses always killed their hosts, the virus will run out of hosts to infect
