TABLE 2.
Hybridization of central fimP (type 1) and fimA (type 2) gene probes with chromosomal DNA from strains of A. naeslundii and A. odontolyticus with defined binding specificities and tissue origin
| Species and site of isolationa | No. of isolates hybridized withb:
|
No. of isolates with:
|
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
|
fimP central DNA probe
|
fimA central DNA probes
|
APRP specificityc
|
GalNAcβ specificityd
|
||||||||
| Pos | Neg | Type 2:1
|
Type 2:2
|
Pos | Neg | Type 2:1 | Type 2:2 | Neg | |||
| Pos | Neg | Pos | Neg | ||||||||
| A. naeslundii genospecies 1 (n = 20) | |||||||||||
| Tooth (n = 18) | 6 | 12 | 18 | 18 | 5 | 13 | 18 | ||||
| Buccal mucosa (n = 2) | 2 | 2 | 2 | 2 | 2 | ||||||
| Tongue (n = 0) | |||||||||||
| A. naeslundii genospecies 2 (n = 63) | |||||||||||
| Tooth (n = 41) | 40 | 1 | 41 | 41 | 41 | 41 | |||||
| Buccal mucosa (n = 1) | 21 | 21 | 21 | 21 | 21 | ||||||
| Tongue (n = 1) | 1 | 1 | 1 | 1 | 1 | ||||||
| A. odontolyticus (n = 19) | |||||||||||
| Tooth (n = 1) | 1 | 1 | 1 | 1 | 1 | ||||||
| Buccal mucosa (n = 1) | 1 | 1 | 1 | 1 | 1 | ||||||
| Tongue (n = 17) | 17 | 17 | 17 | 1 | 16 | 17 | |||||
The isolates were identified by multivariate statistical analysis of phenotypic characteristics, serology, and protein banding patterns of cell extracts analyzed with SDS-PAGE (18). Strains isolated from eight individuals were grouped based on tissue origin (tooth, buccal mucosa, or tongue) or binding specificity.
The central type 1 DNA probe was generated from the fimP fimbrial subunit gene of A. naeslundii T14V, and the central type 2:1 and type 2:2 DNA probes were generated from the variant fimA fimbrial subunit genes of A. naeslundii ATCC 12104T and P-1-N (CCUG 33910), respectively. The probes were labeled with digoxigenin and used in slot blot hybridization with chromosomal DNA from Actinomyces species under high-stringency conditions. The degree of hybridization was scored from 0 to 6 according to the following densitometric values; 0 = <0.01, 1 = 0.01 to <0.04, 2 = 0.04 to <0.10, 3 = 0.10 to <0.16, 4 = 0.16 to <0.22, 5 = 0.22 to <0.27, and 6 = ≥0.27. Positive signals (Pos) denote hybridization reactions with scores of 2 to 6 and negative signals (Neg) denote hybridization reactions with scores of 0 to 1. The majority of strains showed hybridization reactions with scores of 3 to 4. Essentially identical results, though analyzed for only half of the strains, were obtained under low-stringency conditions.
APRP specificity denotes binding to APRPs adsorbed onto hydroxyapatite beads (18, 19). All APRP-binding isolates showed preferential binding in the order of APRP-1 > APRP-3 > statherin (18, 19).
GalNAcβ specificity denotes hemagglutination and aggregation of Actinomyces strains with a collection of streptococcal strains in a GalNAcβ1-3Galα-O-ethyl-inhibitable fashion (18, 19). The different GalNAcβ specificities, types 2:1 and 2:2, denote different aggregation patterns with S. oralis Ss34 and MPB1: type 2:1 coaggregates with both strains, while type 2:2 coaggregates only with Ss34 (18, 19). Negative GalNAcβ binding is characterized as aggregation of Actinomyces with streptococci that was not inhibited in the presence of GalNAcβ1-3Galα-O-ethyl (18, 19).