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Neisseria gonorrhoeae MS11mkC opacity protein expression in vitro and during human volunteer infectivity studies
K A Schmidt1, C D Deal, M Kwan
1Department of Bacterial Diseases, Walter Reed Army Institute of Research, Washington DC, USA. katherine.a.schmidt@dartmouth.edu
Background And Objectives:
Neisseria gonorrhoeae MS11mkC harbors 11 independently expressed opacity (Opa) protein genes with distinct in vitro expression frequencies. In experimental infections in which human male volunteers were inoculated with transparent (Opa), piliated (P+) strains, the authors associate onset of symptoms with recovery of opaque (Opa+) gonococci.
Goals:
In vitro and recovered (Opa) protein expression rates were compared to determine if the human host influences Opa expression.
Study Design:
Opa expression was determined using Western immunoblot analysis; Opa sizes were determined using a scanning densitometer.
Results:
Seven of 10 Opa proteins were identified in gonococci recovered from all of the volunteers at frequencies consistent with in vitro results (Opa C, 29.5 kDa; Opa K, 30 kDa; Opa G, 31 kDa; Opa I, 32 kDa; Opa J, 33 kDa; Opa D, 34 kDa; and Opa H, 37 kDa) (P > or = 0.01, Fisher exact test). Opa B (30.5 kDa) was identified at lower than expected frequencies, whereas Opa E (31.2) and F (31.5) were identified at higher' than expected frequencies. When recovered gonococci were reanalyzed for in vitro expression frequencies, they were consistent with preinfection frequencies.
Conclusions:
The host may influence the prevalence of some Opa proteins.
Insights
The human host may influence Neisseria gonorrhoeae opacity (Opa) protein expression. Some Opa proteins were found at different frequencies in recovered gonococci compared to in vitro levels.
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Neisseria gonorrhoeae possesses 11 independently expressed opacity (Opa) protein genes.
- In experimental infections, symptom onset correlated with the recovery of opaque (Opa+) gonococci.
Purpose of the Study:
- To compare in vitro and in vivo Opa protein expression rates.
- To investigate potential host influence on Opa expression.
Main Methods:
- Opa protein expression was analyzed using Western immunoblot.
- Opa protein sizes were determined via scanning densitometry.
Main Results:
- Seven of 10 Opa proteins were identified in recovered gonococci at frequencies consistent with in vitro expression.
- Opa B, E, and F showed altered frequencies in vivo compared to in vitro.
- Reanalysis confirmed preinfection in vitro expression frequencies.
Conclusions:
- The human host environment may influence the prevalence of specific Opa proteins in Neisseria gonorrhoeae.
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