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. 2016 Oct;22(10):1793–1796. doi: 10.3201/eid2210.151640

Figure 1.

Figure 1

Capsule recovery of Streptococcus suis strain NL119 in vivo. A) The genetic organization of the S. suis serotype 2 capsular polysaccharide synthesis (cps) gene cluster and mutations observed in isolate NL119 and strains retrieved from NL119-infected mice after each in vivo passage (NL119 P1–P4; DDBJ/EMBL/GenBank accession nos. LC147077, LC147078, LC147079, LC147080, and LC077855, respectively). Gray arrows indicate genes putatively involved in capsule synthesis; open arrows indicate genes with unknown functions; numbers indicate nucleotide positions in cps2F. NL119 lost the ability to synthesize the capsule because of a missense mutation at nt 490 (T490C, Cys164Arg) of cps2F (4). B, C) NL119 P1 and P2 retrieved from mice after the first and second in vivo passages, remained nonencapsulated, and their cps2F sequences were identical to that of NL119. In NL119 P3 and P4 retrieved after the third and fourth passages, a further missense mutation at nt 491 (G491C, Arg164Pro) of cps2F restored the function of the gene, resulting in capsule recovery of the strains. Dot-ELISA of NL119 and strains retrieved from NL119-infected mice after each in vivo passage (NL119 P1–P4) using monoclonal antibody Z3 (B) and polyclonal anti–S. suis serotype 2 serum adsorbed with NL119 (C). Monoclonal antibody Z3 specifically recognizes the sialic acid moiety of the S. suis serotype 2 capsule.