MCM 2-24 Viral Pathogenesis Flashcards
difference between +ssRNA and mRNA
sometimes they are the same. mRNA needs cap and poly-A tail to be recognized by a ribosome
sometimes a +RNA must get changed to -RNA first by RDRP, then trascribed into mRNA for the ribosomes
fomites
inanimate objects that have pathogens on them (counters, handles)
susceptibility and severity of viral disease depends on
if it is the correct
exposure route
dose
the status of the person
virus-host interaction - unique genetic features of the person and that viral strain
two viruses that can enter the body through a scratch
HSV1/2 and HPV
describe the epithelial anatomy of the respiratory tract
covered in mucus, ciliated cells and goblet cells with basement membrane (barrier to some viruses). Polarized - the apical is unlike the basal
some viruses enter/leave through the apical (flu)
other enter apical and can pass through the basal membrane
What do M-cells do? How are they effected by some viruses?
M-cells sample the gut contents and present to underlying immune cells.
Some viruses can infect M-cells and easily reach the blood stream.
describe the common features of Reo and Roto-virus
both unenveloped, get sampled by M-cell and can make it across into the blood stream quickly.
Rotovirus
transmission route Virulence factor? Immunity is mediated by? important features? Types?
tranmission is fecal oral
virulence - nonstructure protein 4 (toxin) nsp4 - effects enterocytes causing massive diarreah
immunity is mediated by IgA by prior exposure OR oral vaccine
Important features - there is a vaccine, this is not a summer disease, very little dissemination - “straight shot through”
type a - under 2 years
type b - over 2 years
what is “dissemination” of a virus?
when the virus crosses the basement membrane of the body
describe primary viremia
“viruses may spread form the surface of the body to lymph nodes and blood stream”
“primary viremia leads to replication in internal organs, may occur without symptoms (incubation stage)
first appearance of virions in blood. May not be replicationg, but ability to detect virus in blood at low levels.
any virus that interacts with the respiratory or gut epithelium requires
attatchment and receptor engagement
recognition and attachment
What is secondary Viremia?
the virus disseminates to the virus to organs where it is shed
- trasmission may be by direct contact or through environment
- exposure to infected blood is now a common route of transmission
describe chicken pox
very contagious via respiratory and eyes
replicates in upper airway, travels to lymph nodes and infects T-cells to spread throughout body
- maintained in dorsal root ganglia for life
- virus always detectable in the blood
vaccines for zoster and varicella, some antivrials but they are not very effective
where are the highest levels of HIV found an in infected person?
blood plasma, lymphocytes, CSF, ear secretions
virus infection may be…(5)
unnotticed, cause illness, induce autoimmunity, be persistent, or be lethal
a successful virus will..
avoid destruction by the immune system and avoid destroying the host before replication is complete
Persistent Vs Latent
Persistent - you are able to culture virus in the absense of disease
latent - cannot culture virus in absence of disease
acute - virus goes away