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A Murine Model of Group B Streptococcus Vaginal Colonization
Published on: November 16, 2016
Genotypic Distribution of Alpha-Like Proteins in Group B Streptococcus Strains Isolated in Korea: Implications for
Ji Hyen Lee1,2, Hye-Kyung Cho1,3, Kyung-Hyo Kim1,3
1Center for Vaccine Evaluation and Study, Ewha Womans University College of Medicine, Seoul, Korea.
Insights
Group B Streptococcus (GBS) alpha-like protein (alp) genotypes were studied in Korea. The Rib genotype was most common, suggesting an Alp protein vaccine could protect against prevalent GBS strains.
Area of Science:
- Microbiology
- Immunology
- Epidemiology
Background:
- Group B Streptococcus (GBS) causes severe invasive bacterial diseases in newborns and susceptible adults.
- Vaccine development for GBS is ongoing, targeting antigens like capsular polysaccharides and alpha-like proteins (Alps).
- Epidemiological data on GBS antigens is crucial for vaccine efficacy prediction, with a lack of data on Alps genotypes in Korea.
Purpose of the Study:
- To investigate the distribution and characteristics of the alpha-like protein (alp) genotype in clinical Group B Streptococcus strains in Korea.
- To provide essential epidemiological data for predicting the effectiveness of GBS vaccines, particularly those targeting Alps.
Main Methods:
- Analysis of 386 GBS strains isolated from clinical specimens (2000-2018).
- Serotype verification using slide latex agglutination and polymerase chain reaction for specific genes (bca, rib, alp1-4).
- Classification of strains as invasive or non-invasive based on specimen source and analysis of genotype distribution.
Main Results:
- Serotype III was the most prevalent (28.2%), and 79.5% of strains were covered by existing hexavalent vaccine formulations.
- The rib genotype was the most common alpha-like protein (alp) genotype (39.4%), with higher prevalence in non-invasive strains.
- Invasive strains were primarily isolated from blood, while non-invasive strains were more frequent from vaginal and urethral sites.
Conclusions:
- The distribution of alp genotypes varied between invasive and non-invasive GBS strains, with substantial proportions of bca and rib.
- An Alp protein vaccine incorporating Rib and Cα antigens is anticipated to offer protection against common GBS strains in Korea.
- Further epidemiological studies on GBS vaginal colonization and neonatal strains are recommended for enhanced early sepsis prevention.
Background:
Group B Streptococcus (GBS) is a major cause of invasive bacterial diseases, including sepsis, meningitis, and pneumonia, particularly in newborns and infants. Pregnant adults, those with pre-existing conditions, and older adults are particularly susceptible. Ongoing research is focused on developing various vaccines utilizing different antigens, including capsular polysaccharides and alpha-like proteins (Alps). Epidemiological data on these antigens in GBS is essential for predicting the effectiveness of these vaccines. However, no epidemiological studies on Alps genotype have been conducted in Korea. This study aimed to fill this gap by investigating the distribution and characteristics of the alp genotype in domestic clinical strains.
Materials And Methods:
We analyzed 386 GBS strains isolated from various clinical specimens between April 2000 and November 2018. The serotype of each strain was initially verified using a slide latex agglutination reaction, then confirmed by polymerase chain reaction to determine the presence of the genes bca, rib, alp1, alp2, alp3, and alp4 associated with Alps. Strains were then classified as invasive or non-invasive based on the type of clinical specimen. The distribution of serotypes and alp genotype was analyzed across these classifications.
Results:
We analyzed 386 bacterial strains to assess their clinical characteristics, serotypes, and alp genotype distributions. Of these strains, 47.1% (182 strains) were invasive primarily isolated from blood samples (43.3%, 167 strains), whereas non-invasive strains were more frequently isolated from sites such as the vagina and urethra. Serotype III was the most prevalent across both invasive and non-invasive strains, comprising 28.2% (109 strains) of all isolates. Notably, 79.5% (307 strains) of all isolates were encompassed by the hexavalent vaccine (serotype Ia, Ib, II, III, and V) formulations. Furthermore, the rib genotype was the most common, detected in 39.4% (152 strains) of all isolates, with a higher prevalence in non-invasive samples (44.1%, 90 strains).
Conclusion:
Although the distribution of alp genotypes differed between invasive and non-invasive strains, the proportion of bca and rib was substantial. Therefore, Alp protein vaccine containing Rib and Cα antigens is expected to provide protection against prevalent GBS strains in Korea. Additional epidemiological studies on GBS vaginal colonization in pregnant women and invasive neonatal strains are needed to support early neonatal sepsis prevention in these high-risk groups.
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