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Unencapsulated Streptococcus pneumoniae from conjunctivitis encode variant traits and belong to a distinct phylogenetic cluster.

Valentino MD, McGuire AM, Rosch JW, Bispo PJ, Burnham C, Sanfilippo CM, Carter RA, Zegans ME, Beall B, Earl AM, Tuomanen EI, Morris TW, Haas W, Gilmore MS - Nat Commun (2014)

Bottom Line: Here we perform a comparative genomic analysis of 271 strains of conjunctivitis-causing S. pneumoniae from 72 postal codes in the United States.These strains possess divergent forms of pneumococcal virulence factors (such as CbpA and neuraminidases) that are not shared with other unencapsulated nasopharyngeal S. pneumoniae.They also possess putative adhesins that have not been described in encapsulated pneumococci.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, 243 Charles Street C703, Boston, Massachusetts 02114, USA [2] Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA [3] The Broad Institute of MIT and Harvard, 320 Charles Street, Cambridge, Massachusetts 02141, USA.

ABSTRACT
Streptococcus pneumoniae, an inhabitant of the upper respiratory mucosa, causes respiratory and invasive infections as well as conjunctivitis. Strains that lack the capsule, a main virulence factor and the target of current vaccines, are often isolated from conjunctivitis cases. Here we perform a comparative genomic analysis of 271 strains of conjunctivitis-causing S. pneumoniae from 72 postal codes in the United States. We find that the vast majority of conjunctivitis strains are members of a distinct cluster of closely related unencapsulated strains. These strains possess divergent forms of pneumococcal virulence factors (such as CbpA and neuraminidases) that are not shared with other unencapsulated nasopharyngeal S. pneumoniae. They also possess putative adhesins that have not been described in encapsulated pneumococci. These findings suggest that the unencapsulated strains capable of causing conjunctivitis utilize a pathogenesis strategy substantially different from that described for S. pneumoniae at other infection sites.

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Related in: MedlinePlus

Virulence factor differences between invasive and ECC strainsNew traits found within ECC and closely related genomes are shown in solid blue, with those unique to STs associated with conjunctivitis highlighted with red outline. CbpAC1 and CbpAC2 are shown as CbpAC since ECC strains express one or the other, but not both. Predicted ligands for SspBC1, SspBC2, and CbpAC are shown. Host-derived molecules are illustrated in green. Arrows indicate secreted products.
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Figure 7: Virulence factor differences between invasive and ECC strainsNew traits found within ECC and closely related genomes are shown in solid blue, with those unique to STs associated with conjunctivitis highlighted with red outline. CbpAC1 and CbpAC2 are shown as CbpAC since ECC strains express one or the other, but not both. Predicted ligands for SspBC1, SspBC2, and CbpAC are shown. Host-derived molecules are illustrated in green. Arrows indicate secreted products.

Mentions: We found genes cbpAC1, cbpAC2, nanO1, nanO2 were only carried by STs that are associated with conjunctivitis (see Fig. 6 and Fig. 7). Other genes enriched in ECC, including the sspBC agglutinins, zmpC1, zmpC2, and the triose metabolic cassette, were found to be shared among a few closely related unencapsulated STs (ST6153, ST6691, ST6729, ST2996, ST1054, ST449) that have not been identified in cases of conjunctivitis, which may stem from the paucity of studies that have identified MLST types of S. pneumoniae causing conjunctivitis. These additional genes are largely absent in encapsulated and more distantly related unencapsulated genomes unrelated to conjunctivitis however (see Fig. 6 and Fig. 7). These findings suggest that some of the genes enriched in ECC are fundamental to the formation of the larger unencapsulated lineage to which ECC members belong (see Fig. 6 and Supplemental Fig. 7).


Unencapsulated Streptococcus pneumoniae from conjunctivitis encode variant traits and belong to a distinct phylogenetic cluster.

Valentino MD, McGuire AM, Rosch JW, Bispo PJ, Burnham C, Sanfilippo CM, Carter RA, Zegans ME, Beall B, Earl AM, Tuomanen EI, Morris TW, Haas W, Gilmore MS - Nat Commun (2014)

Virulence factor differences between invasive and ECC strainsNew traits found within ECC and closely related genomes are shown in solid blue, with those unique to STs associated with conjunctivitis highlighted with red outline. CbpAC1 and CbpAC2 are shown as CbpAC since ECC strains express one or the other, but not both. Predicted ligands for SspBC1, SspBC2, and CbpAC are shown. Host-derived molecules are illustrated in green. Arrows indicate secreted products.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4231546&req=5

Figure 7: Virulence factor differences between invasive and ECC strainsNew traits found within ECC and closely related genomes are shown in solid blue, with those unique to STs associated with conjunctivitis highlighted with red outline. CbpAC1 and CbpAC2 are shown as CbpAC since ECC strains express one or the other, but not both. Predicted ligands for SspBC1, SspBC2, and CbpAC are shown. Host-derived molecules are illustrated in green. Arrows indicate secreted products.
Mentions: We found genes cbpAC1, cbpAC2, nanO1, nanO2 were only carried by STs that are associated with conjunctivitis (see Fig. 6 and Fig. 7). Other genes enriched in ECC, including the sspBC agglutinins, zmpC1, zmpC2, and the triose metabolic cassette, were found to be shared among a few closely related unencapsulated STs (ST6153, ST6691, ST6729, ST2996, ST1054, ST449) that have not been identified in cases of conjunctivitis, which may stem from the paucity of studies that have identified MLST types of S. pneumoniae causing conjunctivitis. These additional genes are largely absent in encapsulated and more distantly related unencapsulated genomes unrelated to conjunctivitis however (see Fig. 6 and Fig. 7). These findings suggest that some of the genes enriched in ECC are fundamental to the formation of the larger unencapsulated lineage to which ECC members belong (see Fig. 6 and Supplemental Fig. 7).

Bottom Line: Here we perform a comparative genomic analysis of 271 strains of conjunctivitis-causing S. pneumoniae from 72 postal codes in the United States.These strains possess divergent forms of pneumococcal virulence factors (such as CbpA and neuraminidases) that are not shared with other unencapsulated nasopharyngeal S. pneumoniae.They also possess putative adhesins that have not been described in encapsulated pneumococci.

View Article: PubMed Central - PubMed

Affiliation: 1] Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, 243 Charles Street C703, Boston, Massachusetts 02114, USA [2] Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA [3] The Broad Institute of MIT and Harvard, 320 Charles Street, Cambridge, Massachusetts 02141, USA.

ABSTRACT
Streptococcus pneumoniae, an inhabitant of the upper respiratory mucosa, causes respiratory and invasive infections as well as conjunctivitis. Strains that lack the capsule, a main virulence factor and the target of current vaccines, are often isolated from conjunctivitis cases. Here we perform a comparative genomic analysis of 271 strains of conjunctivitis-causing S. pneumoniae from 72 postal codes in the United States. We find that the vast majority of conjunctivitis strains are members of a distinct cluster of closely related unencapsulated strains. These strains possess divergent forms of pneumococcal virulence factors (such as CbpA and neuraminidases) that are not shared with other unencapsulated nasopharyngeal S. pneumoniae. They also possess putative adhesins that have not been described in encapsulated pneumococci. These findings suggest that the unencapsulated strains capable of causing conjunctivitis utilize a pathogenesis strategy substantially different from that described for S. pneumoniae at other infection sites.

Show MeSH
Related in: MedlinePlus