Biosurveillance: a systematic review of global infectious disease surveillance systems from 1900 to 2016.

Biosurveillance is crucial to detect, identify and minimise the negative consequences of infectious disease. Its value to society and importance to global public health and global health security are growing. Despite the long history and global importance of biosurveillance, a systematic review of all existing biosurveillance systems across the 'One Health' spectrum has not yet been published. This study conducted a systematic review to identify all extant and defunct biosurveillance systems from 1900 to 2016. Of the 815 systems examined, the majority surveyed human, animal or plant data discretely. Some 105 collected human and animal data, whereas only 31 collected data on all three categories. The authors found a large increase in the number of global biosurveillance systems between 1900 and 2008, but a reduction in the number of biosurveillance systems from 2008 to the present. The number of syndromic systems created, versus laboratory-based biosurveillance systems, increased rapidly after 1980 across the globe.

La surveillance biologique est un procédé essentiel pour détecter, caractériser et minimiser les effets négatifs des maladies infectieuses. Son rôle à l'égard de la société et son importance pour la santé publique et la sécurité sanitaire mondiale ne cessent de croître. Malgré l'histoire déjà longue et l'importance mondiale de la surveillance biologique, aucun inventaire systématique des systèmes de surveillance biologique mis en œuvre dans une perspective « Une seule santé ¼ n'avait été publié jusqu'à ce jour. La présente étude résume les résultats d'un examen systématique portant sur tous les systèmes de surveillance biologique appliqués entre 1900 et 2016, qu'ils aient été arrêtés ou qu'ils soient encore utilisés aujourd'hui. La majorité des 815 systèmes examinés exploite des données relatives soit aux êtres humains, soit aux animaux, soit aux plantes. Près de 105 systèmes recueillent à la fois des données sur l'être humain et sur les animaux et 31 systèmes seulement recueillent des données sur les trois catégories en même temps. Les auteurs ont constaté une forte augmentation du nombre de systèmes de surveillance biologique dans le monde entre 1900 à 2008, puis un déclin de ce nombre entre 2008 et aujourd'hui. Le nombre de systèmes syndromiques, par opposition aux systèmes de surveillance biologique basés sur les examens de laboratoire a connu une augmentation rapide dans le monde entier à partir de 1980.

La vigilancia biológica (o biovigilancia), indispensable para discernir, detectar y reducir al mínimo las consecuencias negativas de una enfermedad infecciosa, reviste cada vez más interés para la sociedad y más importancia para la salud pública y la seguridad sanitaria mundiales. Pese a la dilatada historia y a la relevancia mundial de la vigilancia biológica, hasta ahora nunca se había publicado un examen sistemático de todos los sistemas de biovigilancia existentes dentro del espectro de «Una sola salud¼. Los autores describen un estudio encaminado a examinar de forma sistemática todos los sistemas de vigilancia biológica, aún vigentes o ya extintos, instaurados entre 1900 y 2016. La mayoría de los 815 sistemas examinados estaban dedicados a la vigilancia específica de las personas, los animales o las plantas. En unos 105 se obtenían datos de humanos y anímales, y solo en 31 de ellos se recogían datos de las tres categorías. Los autores observaron un marcado incremento del número de sistemas mundiales de biovigilancia entre 1900 y 2008, número que en cambio se fue reduciendo a partir de 2008. De 1980 en adelante se aceleró en todo el globo la creación de sistemas sindrómicos, por oposición a sistemas de biovigilancia basados en el trabajo en laboratorio.

An overview of internet biosurveillance.

Internet biosurveillance utilizes unstructured data from diverse web-based sources to provide early warning and situational awareness of public health threats. The scope of source coverage ranges from local media in the vernacular to international media in widely read languages. Internet biosurveillance is a timely modality that is available to government and public health officials, healthcare workers, and the public and private sector, serving as a real-time complementary approach to traditional indicator-based public health disease surveillance methods. Internet biosurveillance also supports the broader activity of epidemic intelligence. This overview covers the current state of the field of Internet biosurveillance, and provides a perspective on the future of the field.

Influenza A (H1N1) reports

It's a map which presents epidemiological data about the influenza A (H1N1) influenza based on reports from the CDC, the WHO and the HealthMap database. It can be shown by categories (ruled out, suspected, confirmed, cases and death) and by countries.

The alpha C protein mediates internalization of group B Streptococcus within human cervical epithelial cells.

Group B Streptococcus (GBS) is the leading cause of bacterial chorioamnionitis and neonatal pneumonia, sepsis, and meningitis. Deletion of the alpha C protein gene (bca) attenuates the virulence of GBS in an animal model; significant survival differences in the first 24 h of infection suggest a pathogenic role for the alpha C protein early in the infection process. We examined the role of alpha C protein in the association between GBS and mucosal surfaces using a human cervical epithelial cell line, ME180. Fluorescent and confocal microscopy and flow cytometry demonstrated that 9-repeat alpha C protein binds to the surface of ME180 cells. Isolated N-terminal region of this protein also binds to these cells and competitively inhibits binding of the full protein. Wild-type GBS strain A909 and the bca-null isogenic mutant JL2053 bound similarly to the surface of ME180 cells. However, A909 entered these cells threefold more. Internalization of A909 was inhibited with 2- and 9-repeat alpha C and with N-terminal region alone but not by repeat region-specific peptide. Translocation across polarized ME180 membranes was fivefold greater for A909 than for JL2053. These findings suggest a role for the alpha C protein in interaction with epithelial surfaces and initiation of infection.

Tandem repeat deletion in the alpha C protein of group B streptococcus is recA independent.

Group B streptococci (GBS) contain a family of protective surface proteins characterized by variable numbers of repeating units within the proteins. The prototype alpha C protein of GBS from the type Ia/C strain A909 contains a series of nine identical 246-bp tandem repeat units. We have previously shown that deletions in the tandem repeat region of the alpha C protein affect both the immunogenicity and protective efficacy of the protein in animal models, and these deletions may serve as a virulence mechanism in GBS. The molecular mechanism of tandem repeat deletion is unknown. To determine whether RecA-mediated homologous recombination is involved in this process, we identified, cloned, and sequenced the recA gene homologue from GBS. A strain of GBS with recA deleted, A909DeltarecA, was constructed by insertional inactivation in the recA locus. A909DeltarecA demonstrated significant sensitivity to UV light, and the 50% lethal dose of the mutant strain in a mouse intraperitoneal model of sepsis was 20-fold higher than that of the parent strain. The spontaneous rate of tandem repeat deletion in the alpha C protein in vitro, as well as in our mouse model of immune infection, was studied using A909DeltarecA. We report that tandem repeat deletion in the alpha C protein does occur in the absence of a functional recA gene both in vitro and in vivo, indicating that tandem repeat deletion in GBS occurs by a recA-independent recombinatorial pathway.

Pyogenic liver abscesses.

Pyogenic liver abscess is a classic clinical entity whose presentation and management have evolved significantly with the advent of potent antimicrobials and the availability of improved diagnostic imaging. The classic triad of fever, upper right quadrant pain or fullness, and jaundice resulting from advanced pylephlebitis is now seldom seen. Despite these changes, pyogenic liver abscess remains an important clinical entity for which prompt recognition and treatment are essential to achieve a favorable outcome. This article discusses the presentation and diagnosis of and current therapy for liver abscesses.

Mosaicism in the alpha-like protein genes of group B streptococci.

Members of a family of repeat-containing surface proteins of group B streptococci (GBS) defined by the alpha C and Rib proteins exhibit size variability and cross-reactivity and have been studied as potential vaccine components. We report evidence of horizontal DNA transfer with subsequent recombination as a mechanism generating diversity within this antigen family. Alp2 and Alp3 are additional members of the alpha C protein family identified in strains of the emerging GBS serotypes V and VIII. Each contains an overall genetic organization highly similar to that of the alpha C and Rib proteins, including a tandem repeat region and conserved N- and C-terminal regions. Among different strains, protein size varies according to the number of tandem repeats within the corresponding gene. Unlike the alpha C and Rib proteins, however, the newly described alpha-like proteins contain other regions, including one similar to the IgA-binding region of the GBS beta C protein, a nontandem repeat region, and an isolated repeat highly homologous to the alpha C repeat. Sequence analysis of the regions flanking the alpha C protein gene on a 13.7-kb insert reveals several ORFs that are likely to be involved in basic metabolic pathways. Analysis of corresponding flanking regions in other GBS strains, including the parent strains of the newly described alpha-like proteins, shows striking conservation among all strains studied. These findings indicate that the alpha-like proteins are encoded by mosaic variants at a single genomic locus and suggest that recombination after horizontal DNA transfer is a means of generating diversity within this protein family.

A randomized trial of conjugated group B streptococcal type Ia vaccine in a rabbit model of ascending infection.

OBJECTIVE: Maternal vaccination may become a central strategy in the prevention of early-onset group B Streptococcal sepsis. Unlike earlier group B streptococcal polysaccharide vaccines that were poorly immunogenic, newer vaccines conjugated to tetanus toxoid have been developed and have improved immunogenicity. We sought to evaluate a conjugated vaccine using our rabbit model of ascending infection. STUDY DESIGN: Rabbit does were randomized to receive either conjugated group B streptococcal type Ia (Ia-tetanus toxoid) or conjugated group B streptococcal type III (III-tetanus toxoid) vaccine. Does were vaccinated 7 days before conception and 7 and 21 days after conception. On days 28 to 30 of a 30-day gestation, does were inoculated intracervically with 10(6) colony-forming units of type Ia group B Streptococcus. Labor was induced if does were undelivered after 72 hours. Does were observed up to 7 days after inoculation. Offspring were observed up to 4 days. We obtained maternal cultures from the uterus, peritoneum, and blood and offspring cultures from the mouth, anus, and blood. Antibody levels were also determined. RESULTS: Offspring survival was significantly improved in the group receiving Ia-tetanus toxoid (P =.047). Outcomes such as maternal sepsis and severe illness, although not reaching statistical significance, showed a trend toward improved outcomes in the Ia-tetanus toxoid group. CONCLUSIONS: This is the first study to evaluate the conjugated group B streptococcal vaccine by using any model of ascending infection. The Ia-tetanus toxoid vaccine led to improved survival and was immunogenic but fell short of its expected efficacy in preventing ascending group B streptococcal disease under these experimental conditions.

Regulation of cell component production by growth rate in the group B Streptococcus.

Group B Streptococcus (GBS) is the leading cause of bacterial sepsis and meningitis among neonates. While the capsular polysaccharide (CPS) is an important virulence factor of GBS, other cell surface components, such as C proteins, may also play a role in GBS disease. CPS production by GBS type III strain M781 was greater when cells were held at a fast (1.4-h mass-doubling time [td]) than at a slow (11-h td) rate of growth. To further investigate growth rate regulation of CPS production and to investigate production of other cell components, different serotypes and strains of GBS were grown in continuous culture in a semidefined and a complex medium. Samples were obtained after at least five generations at the selected growth rate. Cells and cell-free supernatants were processed immediately, and results from all assays were normalized for cell dry weight. All serotypes (Ia, Ib, and III) and strains (one or two strains per serotype) tested produced at least 3.6-fold more CPS at a td of 1. 4 h than at a td of 11 h. Production of beta C protein by GBS type Ia strain A909 and type Ib strain H36B was also shown to increase at least 5.5-fold with increased growth rate (production at a td of 1. 4 h versus 11 h). The production of alpha C protein by the same strains did not significantly change with increased growth rate. The effect of growth rate on other cell components was also investigated. Production of group B antigen did not change with growth rate, while alkaline phosphatase decreased with increased growth rate. Both CAMP factor and beta-hemolysin production increased fourfold with increased growth rate. Growth rate regulation is specific for select cell components in GBS, including beta C protein, alkaline phosphatase, beta-hemolysin, and CPS production.

Alpha C protein as a carrier for type III capsular polysaccharide and as a protective protein in group B streptococcal vaccines.

The alpha C protein, a protective surface protein of group B streptococci (GBS), is present in most non-type III GBS strains. Conjugate vaccines composed of the alpha C protein and type III capsular polysaccharide (CPS) might be protective against most GBS infections. In this study, the type III CPS was covalently coupled to full-length, nine-repeat alpha C protein (resulting in III-alpha9r conjugate vaccine) or to two-repeat alpha C protein (resulting in III-alpha2r conjugate vaccine) by reductive amination. Initial experiments with the III-alpha9r vaccine showed that it was poorly immunogenic in mice with respect to both vaccine antigens and was suboptimally efficacious in providing protection in mice against challenge with GBS. Therefore, modified vaccination protocols were used with the III-alpha2r vaccine. Female mice were immunized three times with 0.5, 5, or 20 microgram of the III-alpha2r vaccine with an aluminum hydroxide adjuvant and bred. Ninety-five percent of neonatal mice born to dams immunized with the III-alpha2r vaccine survived challenge with GBS expressing type III CPS, and 60% survived challenge with GBS expressing wild-type (nine-repeat) alpha C protein; 18 and 17%, respectively, of mice in the negative control groups survived (P, <0.0001). These protection levels did not differ significantly from those obtained with the type III CPS-tetanus toxoid conjugate vaccine and the unconjugated two-repeat alpha C protein, which protected 98 and 58% of neonates from infection with GBS expressing type III CPS or the alpha C protein, respectively. Thus, the two-repeat alpha C protein in the vaccine was immunogenic and simultaneously enhanced the immunogenicity of type III CPS. III-alpha vaccines may be alternatives to GBS polysaccharide-tetanus toxoid vaccines, eliciting additional antibodies protective against GBS infection.

Serotypes VI and VIII predominate among group B streptococci isolated from pregnant Japanese women.

Infection by group B streptococcus (GBS) is an important cause of bacterial disease in neonates, pregnant women, and nonpregnant adults. Whereas serotypes Ia, Ib, II, III, and V are most commonly associated with colonization and disease in the United States, strains of other serotypes have been isolated from patients in Japan. By use of an inhibition ELISA, the serotypes of 73 vaginal colonizing GBS strains isolated from healthy pregnant Japanese women were investigated. Twenty-six (35.6%) were type VIII, 18 (24.7%) were type VI, and the remaining 29 were distributed among more traditional serotypes. Strains were also tested by immunoblot for the presence of GBS surface proteins. Fifty-three (72.6%) of the 73 strains expressed one or more laddering GBS proteins. These data show that type VI and VIII GBS strains are common vaginal isolates in pregnant Japanese women and that one or more laddering proteins are present in most GBS strains.

Isolation and chemical characterization of a capsular polysaccharide antigen shared by clinical isolates of Enterococcus faecalis and vancomycin-resistant Enterococcus faecium.

Enterococci are a common cause of serious infections, especially in newborns, severely immunocompromised patients, and patients requiring intensive care. To characterize enterococcal surface antigens that are targets of opsonic antibodies, rabbits were immunized with various gentamicin-killed Enterococcus faecalis strains, and immune sera were tested in an opsonophagocytic assay against a selection of clinical isolates. Serum raised against one strain killed the homologous strain (12030) at a dilution of 1:5,120 and mediated opsonic killing of 33% of all strains tested. In addition, this serum killed two (28%) of seven vancomycin-resistant Enterococcus faecium strains. Adsorption of sera with the homologous strain eliminated killing activity. The adsorbing antigens were resistant to treatment with proteinase K and to boiling for 1 h, but were susceptible to treatment with sodium periodate, indicating that the antigen inducing opsonic activity is a polysaccharide. Antibodies in immune rabbit sera reacted with a capsule-like structure visualized by electron microscopy both on the homologous E. faecalis strain and on a vancomycin-resistant E. faecium strain. The capsular polysaccharides from E. faecalis 12030 and E. faecium 838970 were purified, and chemical and structural analyses indicated they were identical glycerol teichoic acid-like molecules with a carbohydrate backbone structure of 6-alpha-D-glucose-1-2 glycerol-3-PO4 with substitution on carbon 2 of the glucose with an alpha-2-1-D-glucose residue. The purified antigen adsorbed opsonic killing activity from immune rabbit sera and elicited high titers of antibodies (when used to immunize rabbits) that both mediated opsonic killing of bacteria and bound to a capsule-like structure visualized by electron microscopy. These results indicate that approximately one-third of a sample of 15 E. faecalis strains and 7 vancomycin-resistant E. faecium strains possess shared capsular polysaccharides that are targets of opsonophagocytic antibodies and therefore are potential vaccine candidates.

Deletion of repeats in the alpha C protein enhances the pathogenicity of group B streptococci in immune mice.

The alpha C protein is a protective surface-associated antigen of group B streptococci (GBS). The prototype alpha C protein of GBS (strain A909) contains nine identical tandem repeats, each comprising 82 amino acids, flanked by N- and C-terminal domains. Clinical isolates of GBS show variable numbers of repeats with a normal distribution and a median of 9 to 10 repeats. Here, we show that escape mutants of GBS expressing one-repeat alpha C protein were 100-fold more pathogenic than GBS expressing wild-type nine-repeat alpha C protein in neonatal mice whose dams were immunized with antiserum elicited to nine-repeat alpha C protein (50% lethal doses of 1.6 x 10(3) and 1.8 x 10(5), respectively; P = 0.0073). There was no difference in pathogenicity in nonimmune mice. Enzyme-linked immunosorbent assay inhibition showed that nine-repeat but not one-repeat alpha C protein is readily available for antibody binding on the surface of intact GBS. Immune electron microscopy studies with antibodies to the capsular polysaccharide (CPS) and to the alpha C protein demonstrated localization of the nine-repeat alpha C protein and the CPS at similar distances from the cell wall. The one-repeat alpha C protein was visualized poorly and only in close proximity to the cell wall, thus suggesting that antibody binding to the protein was hindered by CPS or other cell surface components. We concluded that deletion in the repeat region of the alpha C protein enhanced the pathogenicity of GBS in immune mice by (i) loss of a protective (conformational) epitope(s) and (ii) loss of antibody binding to the alpha C protein due to a decrease in antigen size relative to cell wall components and/or CPS.

Immunogenicity and protective efficacy of the alpha C protein of group B streptococci are inversely related to the number of repeats.

Infection by group B streptococci (GBS) is an important cause of bacterial disease in neonates. Alpha C protein is a protective cell surface-associated protein of GBS. This protein contains a repeat region flanked by N and C termini. Variable expression of tandem repeating units of alpha C proteins had been found among clinical isolates of GBS. We examined the effect of the number of repeats on the immunogenicity of the alpha C protein and its ability to elicit protection from GBS infection in a neonatal mouse model. Mice were immunized with purified alpha C proteins of constructs containing various numbers of repeats (n = 1, 2, 9, and 16) and the N- and C-terminal regions. Both the N-terminal and the repeat regions contain protective and opsonic epitopes. Antibody responses to the alpha C protein constructs with various numbers of repeats were tested with enzyme-linked immunosorbent assay plates coated with either native, nine-repeat alpha C protein or "repeatless" N-terminal antigen. An inverse relationship was found between the number of repeats and the immunogenicity of the alpha C protein; this effect was most pronounced on titers of antibody to the N-terminal region. An inverse relationship was also observed between the number of repeats and protective efficacy, i.e., mouse dams immunized with 5 microg of one- or nine-repeat alpha C protein transferred protective immunity to 65 or 11% of their pups, respectively (P < 0.0001). Thus, the presence of multiple repeats appears to lessen the antibody response to the complete alpha C protein, and especially the antibody response to its N-terminal region, and suggests a mechanism whereby repeat elements contribute to the evasion of host immunity.

Characterization of two distinct opsonic and protective epitopes within the alpha C protein of the group B Streptococcus.

Group B Streptococcus (GBS) is a major cause of neonatal sepsis, meningitis in early infancy, postpartum endometritis, and serious invasive infections in adults in the United States. We previously cloned, sequenced, and characterized the alpha antigen gene, bca, and showed that the alpha C protein of GBS is a trypsin-resistant, surface-associated polypeptide that contains a signal sequence, a unique N terminus, nine identical tandem repeats, and a C-terminal membrane anchor structure. Polyclonal antiserum raised to the recombinant alpha C protein and an opsonic monoclonal antibody, 4G8, raised to the native protein from GBS have been shown to be protective in a mouse model. The binding site of 4G8 has now been localized to the tandem repeat region of the alpha C protein. To determine whether the N terminus of the alpha C protein contains additional opsonic and/or protective epitopes, the sequence corresponding to the alpha C protein N terminus was subcloned into a pET vector, the expressed peptide from Escherichia coli was purified by Ni2+ affinity chromatography, and rabbit polyclonal antibodies were raised to the purified recombinant peptide. Antibodies to the alpha C protein N terminus were shown to be opsonic by an in vitro opsonophagocytosis assay. In addition, 69% of newborn mouse pups from mothers passively immunized with the antiserum to the recombinant N-terminal polypeptide of the alpha C protein were protected against lethal challenge with GBS A909. These data indicate that at least two distinct regions of the alpha C protein, the N terminus and the tandem repeat region, contain opsonic and protective epitopes.

Cloning and expression in Escherichia coli of a protective surface protein from type V group B streptococci.

This report describes a trypsin-resistant laddering protein purified from a type V strain, a serotype of important emerging clinical significance. This protein is present in a majority of type V clinical strains, elicits protective antibody in an animal model, and is cross-reactive with the alpha C protein and R1. The gene encoding this protein has been cloned; preliminary nucleotide sequence analysis reveals significant homology, though not identity, with the alpha C protein gene. These data support the hypothesis that there exists a family of related but distinct GBS surface proteins which may play a role in immunity to GBS infection.

A protective surface protein from type V group B streptococci shares N-terminal sequence homology with the alpha C protein.

Infection by group B streptococci (GBS) is an important cause of bacterial disease in neonates, pregnant women, and nonpregnant adults. Historically, serotypes Ia, Ib, II, and III have been most prevalent among disease cases; recently, type V strains have emerged as important strains in the United States and elsewhere. In addition to type-specific capsular polysaccharides, many GBS strains possess surface proteins which demonstrate a laddering pattern on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and resistance to trypsin digestion. These include the alpha C protein, the R proteins, and protein Rib. Some of these proteins elicit protective antibodies in animals. We demonstrate a trypsin-resistant laddering protein purified from a type V GBS strain by mutanolysin extraction and column chromatography. This protein contains a major 90-kDa band and a series of smaller bands spaced approximately 10 kDa apart on SDS-PAGE. Cross-reactivity of the type V protein with the alpha C protein and with R1 was demonstrated on Western blot (immunoblot). N-terminal sequence analysis of the protein revealed residue identity with 17 of 18 residues at corresponding positions on the alpha protein. Western blot of SDS extracts of 41 clinical type V isolates with rabbit antiserum to the protein demonstrated a homologous protein in 25 isolates (61%); two additional strains exhibited a heterologous pattern which was also demonstrated with 4G8, a monoclonal antibody directed to the alpha C protein repeat region. Rabbit antiserum raised to the type V protein conferred protection in neonatal mice against a type V strain bearing a homologous protein. These data support the hypothesis that there exists a family of trypsin-resistant, laddering GBS surface proteins which may play a role in immunity to GBS infection.

Variation in repeat number within the alpha C protein of group B streptococci alters antigenicity and protective epitopes.

Variable expression of repeating units of the protective alpha C proteins among clinical isolates of group B streptococci (GBS) may have implications for vaccine development. In this study, alpha C protein genes containing various numbers of repeats (1,2,9, and 16) were cloned in a T7 overexpression vector in Escherichia coli. Expression was induced by isopropyl-beta-D-thiogalactopyranoside, and proteins were purified by anion-exchange, gel filtration, or affinity chromatography or by isoelectric focusing. Rabbits were immunized with purified 1-,2-,9-, or 16-repeat proteins. All proteins appeared to be highly immunogenic. Enzyme-linked immunosorbent assay inhibition with 9-repeat protein as the coating antigen and 9-repeat-antigen-elicited antiserum showed that a 200-fold-higher concentration of 1-repeat antigen than of 9- or 16-repeat antigen was required for 50% inhibition of antibody-antigen binding. The concentration of 2-repeat antigen required for 50% inhibition was intermediate relative to the concentrations of 1- and 9-repeat antigens. These results suggested that antibodies to 9-repeat antigen recognized predominantly a conformational epitope(s) contained in proteins with higher numbers of repeats (9 or 16) but lost considerable binding affinities for an epitope(s) contained in alpha C proteins with fewer repeats (1 or 2). Similar results were obtained with antiserum to 16-repeat antigen. However, antibodies to 1- and 2-repeat antigens recognized 1-,2-,9-,and 16-repeat antigens with equal binding affinities. This finding suggested that 1- and 2-repeat-elicited antibodies recognized an epitope(s) on individual repeats. Loss of repeating units from the alpha C proteins may result in decreased protection because the loss of epitopes (including conformational epitopes) gives the microorganisms the opportunity to escape host antibodies. If 1- and 2-repeat-elicited antibodies bind all alpha C proteins with equal affinity, regardless of their repeat number, they may prevent GBS strains with fewer repeats from escaping host immunity. Protection data obtained with antisera to the proteins with different repeat numbers support this hypothesis: mouse pups challenged with GBS strain A909 were better protected when immunized with 1- or 2-repeat-elicited antiserum (76 and 75%, respectively) than when immunized with 9- or 16-repeat-elicited antiserum (41 and 48%, respectively).