Identification and assessment of new vaccine candidates for group A streptococcal infections

McMillan, David; Batzloff, Michael R.; Browning, C; Davies, Mark R.; Good, Michael F.; Sriprakash, Kadaba S.; Janulczyk, Robert; Rasmussen, Magnus

doi:10.1016/j.vaccine.2004.01.043

Cited by 21 publications

(9 citation statements)

References 24 publications

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“…Since this threonine-rich region is immediately followed by the LPVTG consensus motif typical of membraneanchored surface proteins of S. suis and many other gram-positive bacteria and since the region is proximal to the second hydrophobic domain, which is located in the cell membrane, it would be expected to lie within the peptidoglycan layer of the cell wall. The LPXTG motif has been found to be highly conserved among all C-terminally anchored proteins examined so far (11,36,40,44,45,51). However, while positions 1, 2, 4, and 5 are nearly completely conserved, position 3 is variable, with several amino acid substitutions, predominantly A, Q, E, T, N, D, K, and L (10).…”

Section: Discussionmentioning

confidence: 97%

Identification of a Surface Protein of Streptococcus suis and Evaluation of Its Immunogenic and Protective Capacity in Pigs

Martínez

Gottschalk

et al. 2006

Infect Immun

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A Streptococcus suis surface protein reacting with convalescent-phase sera from pigs clinically infected by S. suis type 2 was identified. The apparent 110-kDa protein, designated Sao, exhibits typical features of membraneanchored surface proteins of gram-positive bacteria, such as a signal sequence and an LPVTG membrane anchor motif. In spite of high identity with the partially sequenced genomes of S. suis Canadian strain 89/1591 and European strain P1/7, Sao does not share significant homology with other known sequences. However, a conserved avirulence domain that is often found in plant pathogens has been detected. Electron microscopy using an Sao-specific antiserum has confirmed the surface location of the Sao protein on S. suis. The Sao-specific antibody reacts with cell lysates of 28 of 33 S. suis serotypes and 25 of 26 serotype 2 isolates in immunoblots, suggesting its high conservation in S. suis species. The immunization of piglets with recombinant Sao elicits a significant humoral antibody response. However, the antibody response is not reflected in protection of pigs that are intratracheally challenged with a virulent strain in our conventional vaccination model.Streptococcus suis is an important swine pathogen that causes many pathological conditions, such as arthritis, endocarditis, meningitis, pneumonia, and septicemia (19,21). It is also an important zoonotic agent for humans in contact with colonized, otherwise healthy pigs or their by-products, causing meningitis and endocarditis (1, 53). Thirty-three serotypes (types 1 to 31, 33, and 1/2) based on capsular antigens are currently known (15-17, 22, 24, 43). Type 2 is considered the most virulent and prevalent type in diseased pigs. The mechanisms involved in the pathogenesis and virulence of S. suis are not completely understood (19), and attempts to control the infection are hampered by the lack of an effective vaccine.Several approaches have been used to develop vaccines for S. suis. However, little success was achieved because the protection was either serotype or strain dependent, and results in most instances were equivocal (23, 42). For example, some protection with killed whole cells or live avirulent vaccines was reported, but this required repeated immunization, and the protection against heterologous challenges was not evaluated (25, 56). Exposure of young pigs to live virulent strains showed a positive effect in reducing clinical signs characteristics of S. suis infection (52). Since the S. suis capsule plays an important role in virulence, attempts have been made to develop a vaccine based on capsular material. However, this vaccination approach was unsatisfactory because the capsular polysaccharide is poorly immunogenic (9). More recently, interest has shifted toward protein antigens of S. suis as vaccine candidates. Subunit vaccines using suilysin (27) or muramidase-released protein and extracellular protein factor (57) have been shown to protect pigs from homologous and heterologous serotype 2 strains, but their use is hindered by ...

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Section: Discussionmentioning

confidence: 97%

Identification of a Surface Protein of Streptococcus suis and Evaluation of Its Immunogenic and Protective Capacity in Pigs

Martínez

Gottschalk

et al. 2006

Infect Immun

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“…Light microscopy has long been the method of choice for the rapid characterization of bacteria that have not been purified ( in situ microscopy). Results include finding that bacterial aggregation state is a classification criterion that correlates with both disease‐causing and bioremediation potential, especially when coupled with immunofluorescence properties (Rojas et al ., 2002; McMillan et al ., 2004; Chaerun et al ., 2004). Aggregation state is a defining aspect of biofilm‐forming bacteria (Webb et al ., 2003, 2004; Barnhart & Chapman, 2006).…”

Section: Introductionmentioning

confidence: 99%

In situ fluorescence microscopy of bacteriophage aggregates

Serwer¹,

Hayes²,

Lieman³

et al. 2007

Journal of Microscopy

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SummaryVirus aggregation is analyzed because of its potential use for both classifying viruses and understanding virus ecology and evolution. Virus aggregation is, however, problematic because aggregation causes loss of virions during processing for microscopy of any type. Thus, here we detect virus aggregation by fluorescence microscopy of wet-mounted dissections of dilute gel-supported plaques (in situ fluorescence microscopy) of a test virus, the long-tail aggregating Bacillus thuringiensis bacteriophage, 0305φ8-36. Background fluorescence is reduced to nonproblematic levels by using the dye, DAPI (4 ,6-diamidino-2-phenylindole), to stain viral nucleic acid. In situ fluorescence microscopy reveals two in situ phases, one weakly fluorescent. Most bacteriophages partition to the weakly fluorescent phase. Aggregates of bacteriophage 0305φ8-36 are detected during fluorescence microscopy via the following. (1) Coordinated motion is found for visibly separate particles in solution; the motion is either thermally generated, fluid drift-induced or mechanical pressure-induced. (2) Aggregate dissociation is observed. Some of the larger aggregates are elastic and entangled with material of the weakly fluorescent phase. The larger aggregates sometimes sink at 1-g within specimens. In situ fluorescence microscopy rapidly distinguishes 0305φ8-36 from nonaggregating bacteriophages.

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“…Streptococcal protective antigen GAS [50] In clinical trials as component of multivalent M C5a peptidase [51] Animal and natural infection studies Fibronectin-binding protein [52] Serum opacity factor [53,54] Streptococcal pyrogenic exotoxin B (extracellular cysteine protease) [55] Streptococcal pyrogenic exotoxin C [56] Pili (T antigen) [57] Serine protease (SpyCEP) [58] Serine esterase (Sse) [59] GAS 40 [60] Nine common antigens [39] Animal studies G-related alpha2-macroglobulin binding protein (GRAB) [61] Metal transporter of streptococcus (MtsA) [61] Superoxide dismutase [62] Lipoproteins [63] Identified only…”

Section: Non-m Protein Vaccine Candidatesmentioning

confidence: 99%