Presence of multiple copies of the capsulation b locus in invasive Haemophilus influenzae type b (Hib) strains isolated from children with Hib conjugate vaccine failure.
Most invasive Haemophilus influenzae type b strains possess a duplication of the capsulation locus. Further amplification resulting in as many as 5 copies has been described. To verify whether amplification is involved in vaccine failure, the number of copies of the locus was determined by Southern blotting in 90 strains from children with true vaccine failure (TVF) between 1993 and 1999 and in 139 strains from unvaccinated children (50 collected between 1993 and 1999 and 89 collected between 1991 and 1992, before routine immunization was introduced). A significantly greater proportion of strains from TVFs contained multiple copies, compared with strains from control children (24% vs. 10%; P = .0379), which suggests that amplification of the capb locus may be a contributory factor in vaccine failure. The presence of multiple-copy strains was associated with disease other than meningitis.
Cerquetti
Marina
M
Department of Infectious, Parasitic and Immune-Mediated Diseases, Istituto Superiore di Sanita, Rome, Italy. mcerquet@iss.it
Cardines
Rita
R
Ciofi Degli Atti
Marta Luisa
ML
Giufré
Maria
M
Bella
Antonino
A
Sofia
Tonino
T
Mastrantonio
Paola
P
Slack
Mary
M
D016667:Bacterial Capsules; D002675:Child, Preschool; D004279:DNA, Viral / Q000737:chemistry / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005784:Gene Amplification; D018628:Gene Dosage; D006192:Haemophilus Infections / Q000382:microbiology* / Q000517:prevention & control; D018073:Haemophilus Vaccines / Q000235:genetics* / Q000276:immunology* / Q000627:therapeutic use; D019741:Haemophilus influenzae type b / Q000235:genetics* / Q000276:immunology* / Q000302:isolation & purification; D006801:Humans; D015994:Incidence; D007223:Infant; D008583:Meningitis, Haemophilus / Q000382:microbiology / Q000517:prevention & control; D011135:Polysaccharides, Bacterial / Q000235:genetics* / Q000276:immunology* / Q000627:therapeutic use; D018074:Vaccines, Conjugate / Q000276:immunology / Q000627:therapeutic use
D004279:DNA, Viral; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D011135:Polysaccharides, Bacterial; D018074:Vaccines, Conjugate