Genomic and pathogenic investigations of Streptococcus suis serotype 7 population derived from a human patient and pigs.

Streptococcus suis is one of the important emerging zoonotic pathogens. Serotype 2 is most prevalent in patients worldwide. In the present study, we first isolated one S. suis serotype 7 strain GX69 from the blood culture of a patient with septicemia complicated with pneumonia in China. In order to deepen the understanding of S. suis serotype 7 population characteristics, we investigated the phylogenetic structure, genomic features, and virulence of S. suis serotype 7 population, including 35 strains and 79 genomes. Significant diversities were revealed in S. suis serotype 7 population, which were clustered into 22 sequence types (STs), five minimum core genome (MCG) groups, and six lineages. Lineages 1, 3a, and 6 were mainly constituted by genomes from Asia. Genomes of Lineages 2, 3b, and 5a were mainly from Northern America. Most of genomes from Europe (41/48) were clustered into Lineage 5b. In addition to strain GX69, 13 of 21 S. suis serotype 7 representative strains were classified as virulent strains using the C57BL/6 mouse model. Virulence-associated genes preferentially present in highly pathogenic S. suis serotype 2 strains were not suitable as virulence indicators for S. suis serotype 7 strains. Integrative mobilizable elements were widespread and may play a critical role in disseminating antibiotic resistance genes of S. suis serotype 7 strains. Our study confirmed S. suis serotype 7 is a non-negligible pathotype and deepened the understanding of the population structure of S. suis serotype 7, which provided valuable information for the improved surveillance of this serotype.

An efficient fiber-based ELISA for detection of antibody against fowl adenovirus serotypes 7 and 8.

An outbreak of inclusion body hepatitis caused by fowl adenovirus serotype 8 (FAdV-8) has caused significant economic losses in the poultry industry worldwide. However, a rapid serology test kit specific to FAdV-8 is not available to date. We developed a fiber-based ELISA using the purified GST-fiber of FAdV-8 as coating antigen to measure antibodies against FAdV-8. Specificity analysis showed that our ELISA could react with sera against FAdV-7, -8a, and -8b, but not with sera against the other pathogens tested. Moreover, detection of positive sera with our ELISA had 83% and 94% agreement with an indirect immunofluorescence assay (IFA) and a commercial ELISA from BioChek, respectively. Our ELISA was also effective in the detection of antibodies against FAdV-8 in sera from both experimentally infected and clinically vaccinated chickens. Our FAdV-8 fiber-based ELISA can be a valuable tool to specifically and sensitively detect antibodies against FAdV-7 and/or -8 in infected or vaccinated chickens.

A novel human monoclonal antibody potently neutralizes human adenovirus serotype 7 by primarily targeting the adenovirus hexon protein.

Human adenovirus serotype 7 (HAdV-7), belonging to species B, has caused severe lower respiratory tract diseases and even deaths recently. However, no adenovirus vaccine or therapeutic is available thus far. In this study, a HAdV-7-specific human monoclonal antibody (HMAb), 3-3E, isolated from single plasma cells obtained from the peripheral blood mononuclear cells of HAdV-7-infected patients showed potent HAdV-7 neutralization activity. The results showed HMAb 3-3E only binds to the hexon protein of intact HAdV-7 or the recombinant hexon protein and it does not bind to other intact virion particles. This could mean the antibody recognizes a conformational epitope of the hexon protein. Further, HMAb 3-3E potently neutralized HAdV-7 in vitro at low concentrations. In vivo studies showed HMAb 3-3E protected from HAdV-7 infection in a murine model. Therefore, HMAb 3-3E is promising as a safe and effective prophylactic and therapeutic treatment for HAdV-7 infection.

[Meningitis caused by Streptococcus pneumoniae serotype 7a in an infant vaccinated with two doses of 13-valent pneumococcal conjugate vaccine: a case study]. / Méningite à Streptococcus pneumoniae sérotype 7A chez un nourrisson immunisé par deux doses du vaccin pneumococcique conjugué 13-valent: à propos d'un cas.

Pneumococcal meningitis is a global scourge. It is a major cause of morbidity and mortality. In Morocco, 13-valent pneumococcal conjugate vaccine (PCV13) was introduced into the National Immunization Program in October 2010 according to the immunization schedule 2 + 1 and replaced by PCV10 in July 2012, according to the same schedule. Despite the use of the PCV13, which is essential in the fight against pneumococcal disease, the emergence of new non-vaccine serotypes always results in meningitis in children, causing serious sequelae. We report the case of an infant vaccinated with two doses of PCV13 with meningitis caused by Streptococcus pneumoniae serotype 7a. The peculiarity of this case study lies in pneumococcal meningitis due to Streptococcus pneumoniae serotype 7a not included in the PCV13 in an infant immunized by 2 doses of PCV13. We here insist on the need and the importance of an observatory for pneumococcal meningitis and of a wide epidemiological study in order to determine the serotypes in Morocco after the introduction of PCV13 and then of PCV10.

Structure determination of Streptococcus suis serotypes 7 and 8 capsular polysaccharides and assignment of functions of the cps locus genes involved in their biosynthesis.

Streptococcus suis serotypes 7 and 8 are counted among the top six S. suis serotypes causing clinical disease in pigs. Yet, limited information is available on these serotypes. Since S. suis serotyping system is based upon capsular polysaccharide (CPS) antigenicity and the CPS is considered a major virulence factor for encapsulated pathogens, here we determined for the first time the chemical compositions and structures of serotypes 7 and 8 CPSs. Chemical and spectroscopic data gave the following repeating unit sequences: [3)L-Rha(α1-P-2)D-Gal(α1-4)D-GlcA(ß1-3)D-FucNAc4N(α1-]n for serotype 7 and [2)L-Rha(α1-P-4)D-ManNAc(ß1-4)D-Glc(α1-]n for serotype 8. As serotype 8 CPS is identical to Streptococcus pneumoniae type 19F CPS, dot-blot analyses showed a strong reaction of the 19F polysaccharide with reference anti-S. suis serotype 8 rabbit serum. A correlation between S. suis serotypes 7 and 8 sequences and genes of those serotypes' loci encoding putative glycosyltransferases and polymerases responsible for the biosynthesis of the repeating units was tentatively established. Knowledge of CPS structure and composition will contribute to better dissect the role of this bacterial component in the pathogenesis of the disease caused by S. suis serotypes 7 and 8.

Rapid Spread of Pneumococcal Nonvaccine Serotype 7C Previously Associated with Vaccine Serotype 19F, England and Wales.

We observed a sudden and rapid increase in rare invasive pneumococcal disease serotype 7C, from an annual average of 3 cases during 2000-01 through 2015-16 to 29 cases in 2016-17. The increase was caused almost entirely by clonal expansion of sequence type 177, previously associated with vaccine serotype 19F.

Effect of Early-Life Treatment of Piglets with Long-Acting Ceftiofur on Colonization of Streptococcus suis Serotype 7 and Elicitation of Specific Humoral Immunity in a Farm Dealing with Streptococcal Diseases.

In newborn piglets treatment with long-acting ceftiofur is a common approach to reduce losses due to streptococcal diseases on farms, even if problems start after weaning. The purpose of this study was to examine the influence of a single early-life treatment on Streptococcus (S.) suis colonization, transmission, immunoreaction, and drug resistance over an observation period of 14 weeks. In a farm with a history of streptococcal disease and isolation of a S. suis cps 7 mrp+, arcA+ isolate from diseased piglets, half of each litter was treated with a long-acting ceftiofur on day 1. S. suis-isolates were profiled and serum samples were tested for opsonizing antibodies. Treated and untreated pigs did not differ according to average daily weight gains, S. suis-isolation rates and level of opsonizing antibodies. Although the invasive cps 7 strain was not detected in a single piglet over 14 weeks, all animals developed bactericidal activity. No resistance to ceftiofur, but resistance to tetracyclins (100%), and trimethoprim/sulfamethoxazole (53%) was shown. Our results indicate that early treatment with ceftiofur does not prevent colonization and transmission of S. suis or the induction of bactericidal humoral immunity in nursery and fattening pigs. The necessity of continuous usage should be reconsidered.

Identification of the Minimal Glycotope of Streptococcus pneumoniae 7F Capsular Polysaccharide using Synthetic Oligosaccharides.

Streptococcus pneumoniae causes life-threatening diseases including meningitis, pneumonia and sepsis. Existing glycoconjugate vaccines based on purified capsular polysaccharides are widely used and help to prevent millions of deaths every year. Herein, the total syntheses of oligosaccharides resembling portions of the S. pneumoniae serotype 7F (ST7F) capsular polysaccharide repeating unit are reported. To define minimal glycan epitopes, glycan microarrays containing the synthetic oligosaccharides were used to screen human reference serum and revealed that both side chains of the ST7F play a key role in antigen recognition. The identification of protective minimal epitopes is vital to design efficient semi- and fully-synthetic glycoconjugate vaccines.

Differences of the regulation on the expression of mucin 1 ( MUC1 ) induced by adenovirus serotype 5 and serotype 7 infections in airway epithelial cells / 中华微生物学和免疫学杂志

Objective To explore the molecular mechanism for the self-limitation of adenoviral infections in human airway,the different impacts of adenovirus serotype 5 ( Ad5 ) and serotype 7 ( Ad7 ) infections on mucin 1 ( MUC1 ) expression in airway epithelial cells were preliminarily investigated.Methods The Ad5 and the Ad7 infection models were established in A549 cell line.qRT-PCR was performed to determine the transcription of MUC1 mRNA,and the expression of MUC1 in A549 cells infected by Ad5 or Ad7 was by detected Western blot.Results An up-regulation of the MUC1 mRNA level were observed after Ad5 infection for 6 h(P＜0.05 ),and the protein expression level of MUC1 increased in a time-dependent manner in 48 hours of Ad5 infection,while similar response of MUC1 mRNA was absent in Ad7 infection (6 h),even after prolonged (20 h) treatment ( P ＞ 0.05 ).Conclusion This study reveals an up-regulation of MUC1 expression as one of the early immune response to Ad5 infection,which implies that MUC1 may function fully or partially as an anti-inflammatory factor in the self-limitation effect of Ad5 infection.However,type7 adenoviral infection,may introduce a mechanism otherwise,but through MUC1.