LECTURE - Neisseria Flashcards
gram neg diplococci
Neisseria
T or F. meningococcus grows on chocolate agar
T!
purpura
death to tissues = amputattions
infection by Neisseria
- pilis bind to resp epithelium (anchorage)
- tight adherence
- invasion and transcytosis
- invasion and intracellular accommodation or bloodstream =systemic infection
virulence factors of NN. meningitidis
- pili: cellular adherence
- Opa: cellular adherence and invasion
- porin: intracellular survival
- LOS: endotoxin
- LOS-Sialylation: serum resistance
- capsule: anti-phagocytic; serum resistance
- transferrin binding proteins: iron acquisition
virulence factor for N. meningitidis that is the basis for vaccines
capsule!
capsular polysaccharide is basis of __________
serogroup
four most prevalent serogroups (Neisseria meningitidis)
- A
- B
- C
- Y
- W135
meningitis belt
where epidemic group A disease is found (N. meningitidis)
- good vaccine available!! conjugated to tetanus toxoid; minimizes impact of serogroup A!
current vaccination to prevent meningococcal disease
- penicillin and cephalosporins if diagnosed early enough
- contacts of cases are treated with rifampin
- asymptomatic carrier state = few of the people colonized go on to develop meningitis
- Bexsero = multicomponent meningococcal vaccine for serogroup B
why is type B capsular polysaccharide a poor antigen and why is serogroup B vaccine recent?
type B consists of sialic acid residues in similar linkages found on most human cells so it looks like self = autoimmunity risk
serogroup B cap polysacch is chemically identical to
K1 capsular polysaccharide of E. coli
solutions for dealing with group B vaccine wise
- OM vesicle vaccines; isolate blebs; surface proteins
2. reverse vaccinology = identified novel targets
aonther challenge for making a serogroup B vaccine
- proteins expressed from conserved gene sequences were over-expressed
- these proteins were injected into mice to see if they produced a protective response in a mouse model of infection
- Bexsero vaccine
- NadA (Neisserial adhesin A)
- fHbp, factor H binding protein
- NHBA, neisserial heparin-binding antigen
- por A porin protein
T or F. Both meningococcus and gonococcus are oxidase negative
F! positive
where is N. gonorrhea isolated in women?
endocervix or throughout vagina
where is N. gonorrhea isolated in men?
urethra
manifestations of gonorrhea in men vs women
urethritis vs endocervicitis
- can cause ascending infection = sterility if not treated
gonococcus antibiotic resistance
lots of vaccines that it’s resistant to now; so has to be monitored over time
-ceftriaxone is vaccine of choice
main virulence factor for gonococci
type IV pili
- allow gonococci to attach to cell surfaces but also provide a means of movement = twitching motility; grappling hook like Pseudomonas
this makes gonococci 1000-fold more competent by facilitating uptake of DNA
pili
- genetic recombination of homologous regions for genetic diversity (antigenic diversity)
non-piliated vs piliated GC
non = large
piliated = small
opacity can occur in either!!
Opa proteins in GC
- variation occurs due to on-off expression by DNA slip-strand mispairing
- role in adherence to CEACAAMs in vivo
- opacity-associated proteins
pili proteins in GC
- variation occurs when different mini cassettes (mc) in pilin silent genes (pilS) recombine with homologous regions in a pilin expression cassette (pilE)); results in change in pilin size and antigenicity = immune system can’t keep up
