Topic 1-10 (Lecture 10) Flashcards
Where does N. gonorrhoeae adhere to?
Genitourinary tissue (genitals and urinary organ tissues)
How do N. gonorrhoeae attach to tissue?
Pili and surface proteins
What are pili made of ?
PilE proteins or pilin
How does N. gonorrhoeae cause its symptoms?
Attaches to epithelial cell, transcytoses through the cell into subepithelial space where a inflammatory response is induced (and cause the symptoms)
What are opacity-associated proteins (Opa proteins) and their function in N. gonorrhoeae?
They are outer membrane proteins thought to be involved in adherence, and potentially aid in the ability of N. gonorrhoeae to invade host cells
What is antigenic variation?
Method in which bacteria can rearrange genes in its DNA to change the structure of surface molecules to avoid antibodies
What part of the pilin is highly conserved in N. gonorrhoeae?
The N-terminal Region
What is pilE? What is pilS?
pilE = "pilin expression locus" pilS = "silent (non-functional loci" (variant encoding gene)
How does antigenic variation occur in N. gonorrhoeae?
pilS gene is transferred, in whole or in small stretches, into the pilE gene through homologous recombination which results in a chimeric pilin (formed from multiple different genes)
How many variants of pili can be made using antigenic variation?
~ 1 million different antigenic variants
How many copies of pilC genes does N. gonorrhoeae have?
2
What is the role of pilC?
Necessary for assembly and maturation of the pili
acts as an adhesin
How many copies of Opa genes does N. gonorrhoeae have?
10+
What does the different Opa genes allow N. gonorrhoeae to do?
Allows adherence to a variety of cell types
What happens if a mutant lacks Opa proteins?
They are unable to be engulfed by neutrophils
What is an immunodominant protein? (ex. of such protein is the pili)
A protein that is targeted by antibodies (not all antigenic peptide products produced by a bacteria are targeted; immunodominant proteins are the few proteins that are targeted)
How many pilS genes do N. gonorrhoeae have?
10 to 15
What is phase variation?
The process of turning on or off the expression of a particular gene product
How does N. gonorrhoeae use phase variation to evade host defences?
They vary their expression of pili by varying pilE expression. Opa is also varied as none, one, or several different types of opa proteins can be expressed at a given time
What is the full name of N. gonorrhoeae?
Neisseria gonorrhoeae
What are the general properties of N. gonorrhoeae?
Non-motile (doesn't move) Non-sportulating (don't form spores) Gram-negative (has double membrane & LPS) Cocci (coccus, round in shape) Found in pairs (diplococcus, two cocci)
How are N. gonorrhoeae transmitted?
Transmission through contact (cannot survive in environment) via mucous membranes of genitourinary tract
Sexually transmitted infection (STI)
What are the major virulence factors of N. gonnorhoeae?
Adhesins
Antigenic variation
Resistance to killing action of MAC
Iron acquisition
What is the disease caused by N. gonorrhoeae and which specie(s) does it effect?
Gonoorrhea (asymptomatic infection possible)
Affects humans only
How does N. gonorrhoeae affect men and when do those symptoms occur?
Cause urethritis (inflammation of the urethra)
Can cause painful/difficult urination, urethral discharge of pus
Appear 1-14 days after infection
Asymptomatic infections are POSSIBLE
How does N. gonorrhoeae affect women and when do those symptoms occur?
Infection in the endocervix (mucous membrane lining cerivcal canal), possible urethra as well
Symptoms: Cervical-vaginal discharge Painfal/difficult urination Abnormal/inter-menstrual bleeding Absnormal/pelvic pain
Appear 7-21 days after infection
Asymptomatic infection possible
What are possible complications of gonorrhea?
In women PID (Pelivc inflammatory disease)
-Cause sterility and possibly chronic pelvic pain
Gonococcal arthritis
How does N. gonorrhoeae cause disease?
Causing inflammatory response AND avoiding immune response via antigenic variation
How is N. gonorrhoeae treated?
Treatment with antibiotics
IF not treated, often clear within 6 months (i.e. self-limiting infection; a disease with a definite and limited course)
What is opthalmia neonatorum and how is it prevented?
A disease cause by infection of the eyse of a newborn infant by N. gonorrhoeae transmitted by mothers during birth.
Prevented w/ routine use of antibacterial eye drops
What are three techniques used to diagnose gonorrhea?
DNA - Detect presence of bacterial genes in urine samples or cervical swabs
Culture - incubation of the discharge, then perform biochemical tests/study cell and colony morphology to ID
Microscopy - Take discharge sample and stain using gram stain. Presence of gram-negative diplococci indicate gonorrhea typically (gram-negative diplococci are NOT normally present in microbiota)
What antibiotics are used to treat N. gonorrhoeae?
Current option is treatment with cephalosporin and azithromycin
Why are penicillin and tetracycline not used today to treat gonorrhea?
Bacterial resistance gained by plasmids encoding resistance
Is there acquired immunity after N. gonorrhoeae infection?
NO
Why is developing a vaccine for N. gonorrhoeae so difficult?
Antigenic varition of pilin
Lack of suitable animal model
How is N. gonorrhea infections prevented?
Condom use Contact tracing (so identifying people with the disease to prevent its continued spread)
