TABLE 5.
Bacterial strains and vector used in this study
| Strain or plasmid | Serotype | Clinical associationa or application | Tissue origin |
|---|---|---|---|
| S. suis pig isolates | |||
| P1/7 | 2 | SYS-brain | Blood |
| SS021 | 1 | SYS-other | Joint/skin |
| SS045 | 1 | SYS-brain | Meninges |
| SS100 | 1/2 | SYS-brain | Brain |
| SS043 | 1/2 | RESP | Lung |
| SS002 | 2 | SYS-brain | Brain |
| SS008 | 2 | SYS-other | Pericardial swab |
| SS053 | 3 | SYS-brain | Brain |
| SS084 | 3 | RESP | Lung |
| SS062 | 4 | SYS-brain | Brain |
| SS079 | 4 | SYS-brain | Brain |
| SS018 | 7 | SYS-other | Lung/pericardium |
| SS024 | 7 | SYS-brain | Brain |
| SS068 | 8 | SYS-brain | Brain |
| SS091 | 8 | RESP-SD | Lung |
| SS015 | 9 | SYS-brain | Brain |
| SS088 | 9 | SYS-other | Joint |
| SS078 | 10 | SYS-other | Joint |
| SS063 | 14 | SYS-other | Joint |
| SS077 | 14 | SYS-brain | Brain |
| SS097 | 16 | SYS-other | Spleen |
| SS037 | 22 | RESP | Lung |
| SS009 | 23 | RESP | Lung |
| SS082 | 31 | RESP-SD | Lung |
| E. coli strains | |||
| NovaBlue | E. coli host for cloning | ||
| BL21(DE3) | E. coli host for expressing recombinant protein | ||
| pET-30 Ek/LICb vector | Vector for cloning, expression, and purification of target proteins |
Isolates recovered from systemic sites in pigs with clinical signs and/or a gross pathology consistent with S. suis infection (including meningitis, septicemia, and arthritis) were classified as systemic (SYS), whereas those recovered from the lung in the presence of gross lesions of pneumonia were classified as respiratory (RESP). Isolates recovered from the lung of pigs with pneumonia but also with gross signs of systemic streptococcus-type disease were classified as RESP-SD.
The pET-30 Ek/LIC (ligation-independent cloning) vector is designed for cloning and high-level expression of target proteins fused with the His tag and STag coding sequences that are cleavable with enterokinase (Ek) protease. The plasmid contains a strong T7 lac promoter, an optimized ribosome binding site, the coding sequence for the Ek protease cleavage site (Asp Asp Asp Asp Lys↓), and a multiple-cloning site that contains restriction enzyme sites found in many other Novagen expression vectors to facilitate insert transfer. An optional C-terminal His tag-coding sequence is compatible with purification, detection, and quantification.