microbes lecture 2- RNA vs DNA virus Flashcards
what is the darwinian goal of a virus?
reproduction by
1) attachment
2) entry
3) replicate and geen expression
4) assembly
5) release
what are the molecular differences of DNA and RNA?
DNA= uses thymine, double stranded, mainly nuclear and h at 2’ ribose position
RNA= uses uracil, single stranded, nuclear and cytoplasmic and OH at 2’ ribose position
what virus has a faster evolution capacity?
RNA viruses due to their rapid adaptation
what virus has a plastic genome to increase coding capacity?
RNA viruses due to their segmentation, polyproteins and splicing
what viruses are more stable?
dsDNA viruses as they are difficult to detect in the nuclear and persistent infections through latency
what viruses have a greater storage capacity?
dsDNA viruses as they have a broader protein arsenal
what is viral heterogenicity?
Viral heterogeneity drives the adaptability and survival of viruses, complicating efforts to control and treat viral infections while necessitating continuous monitoring and research.
Dependent on mutation rate
Viral fitness will drive selection
Most mutations are neutral with no selection pressure
Negative mutations are typically lost
Positive mutations are selected
Positive selection can change
Mutation rate and positive selection through viral fitness are drivers of antigenic variation
what is antigenic drift?
Antigenic drift is a continuous, incremental evolution in viral antigens, enabling viruses to evade immune defenses and posing challenges for long-term immunity and vaccine development.
a stochastic process in which antigens accumulate small mutations. If any of these results advantageous, it will become predominant through selective pressure.
what are segmented viruses
Segmented viruses have a divided genome structure that promotes diversity and adaptability through reassortment, contributing to their evolutionary success and clinical significance.
Segmented viruses have a genome whose encoded genes are divided across two or more molecules of RNA/DNA. All of them should be incorporated into the viral particle for a virus to be infective.
what is antigenic shift?
Antigenic shift creates novel viral strains through genome reassortment, often leading to pandemics due to a lack of population immunity.
Antigenic shift: major alteration in antigen sequence by a process of genome reassortment (segmented virus) or inter strain recombination.
what is the difference between antigenic shift and drift?
Drift: Gradual changes, leading to slow evolution.
Shift: Abrupt changes, potentially causing global health crises.
what is recombination?
Recombination allows major alterations acquisition of new or functionally altered proteins through exchange of genetic material between viruses or with the host. If can lead to antigenic shift.
what is recombination during replication?
More frequent when the replication mechanism is discontinuous in RNA viruses or because the DNA repair mechanisms in DNA viruses.
what is viral mimicry?
Viral mimicry is a survival tactic where viruses imitate host molecules or processes to evade the immune system and facilitate infection.
what is latency?
Long-lived nature of DNA allows long-lasting infections
Lack of immune response to infected cells in latent state
Impossibility to distinguish ectopic DNA from endogenous DNA in the nucleus
Important clinical consequences: recurrent infections
