Amino acid substitutions in the structural or nonstructural proteins of a vaccine strain of equine arteritis virus are associated with its attenuation

Comparative sequence analysis of a series of strains of equine arteritis virus (EAV) of defined virulence for horses, ranging from the horse-adapted virulent Bucyrus (VB) strain to a fully attenuated vaccine strain derived from it, identified 13 amino acid substitutions associated with attenuation. These include 4 substitutions in the replicase proteins and 9 in the structural proteins. Using reverse genetic techniques, these amino acid substitutions were introduced into a virulent infectious cDNA clone pEAVrVBS derived from the VB strain of EAV. Inoculation of horses with the recombinant viruses clearly demonstrated that changes in either the replicase (nsp1, nsp2 and nsp7) or structural proteins (GP2, GP4, GP5 and M) resulted in attenuation of the virulent VB strain. The recombinant virus with substitutions in the structural proteins was more attenuated than the recombinant virus with substitutions only in the replicase proteins.     

Attenuation of porcine reproductive and respiratory syndrome virus strain MN184 using chimeric construction with vaccine sequence

Two genetically distinct infectious recombinant virus clones (pMLV, constructed from Ingelvac PRRS MLV and pMN184, constructed from virulent strain MN184) were developed to study attenuation of contemporary porcine reproductive and respiratory syndrome virus (PRRSV) strain MN184. Two reciprocal chimeric clones (pMLVORF1/MN184 and pMN184ORF1/MLV) were then constructed, such that the 5'UTR/ORF1 of one genotype was linked to ORF2-7/3'UTR from the other genotype. In vitro studies demonstrated that the rescued chimeric viruses possessed intermediate growth properties compared to recombinant rMLV and rMN184. Swine inoculation with rMN184 and rMLV verified that these viruses fully mimicked the respective parent virus. In addition, earlier and higher antibody responses were detected in animals infected with rMN184 in contrast to those infected with rMLV. Chimeric virus treatment groups showed similar antibody responses as seen with these parent viruses, but much less severe pathogenesis when compared to the rMN184 group. These data suggested that genetic aspects of Ingelvac PRRS MLV 5'UTR/ORF1 replicase region and/or the structural proteins/3'UTR can serve to attenuate virulent strain MN184. The data also indicated that designed PRRSV vaccines could be developed, keeping the known 5'UTR/replicase region of an early vaccine strain such as Ingelvac PRRS MLV intact, but replacing the structural protein/3'UTR domain with that of an emerging virulent virus.     

Homologous recombination evidence in human and swine influenza A viruses

Dynamic gene mutation and the reassortment of genes have been considered as the key factors responsible for influenza A virus virulence and host tropism change. This study reports several significant evidence demonstrating that homologous recombination also takes place between influenza A viruses in human and swine lineages. Moreover, in a mosaic descended from swine H1N1 subtype and human H2N2, we found that its minor putative parent might be a derivative from the human cold-adapted vaccine lineage, which suggests that live vaccine is capable of playing a role in genetic change of influenza A virus via recombination with circulating viruses. These results would be important for knowing the molecular mechanism of mammal influenza A virus heredity and evolution.     

水痘疫苗应急接种效果评价

目的 评价水痘疫苗应急接种效果及暴发后人群抗体水平,指导水痘暴发疫情控制.方法 以2004-2006年发生水痘暴发的17所学校为研究对象,对其中5所学校的患者及密切接触者进行问卷调查,并采集2所学校水痘疫苗应急接种后应急接种者免疫前后血清标本各85份进行水痘疫苗血清抗体滴度测定.结果 应急接种前学校水痘罹患率为6.22％,应急接种后学校水痘罹患率为1.65％,两者的差别有统计学意义(x2=10.99,P＜0.01);接种疫苗者与未接种水痘者的水痘罹患率分别为8.60％和19.89％,免疫人群的水痘罹患率明显低于未免人群(x2=20.70,P＜0.01);接种水痘疫苗后血清抗体有效率为90.70％,抗体阳转率为87.80％,免疫成功率为70.70％.结论 应急接种对控制学校水痘疫情暴发有重要作用,建议在出现水痘病例后,依据病例数目和波及范围,进行相应范围内的应急接种.     

Antibodies and carbohydrate ligands binding to DC-SIGN differentially modulate receptor trafficking

DCs are regarded as key APCs that initiate humoral and cellular immune responses. Consequently, targeted delivery of Ag toward DC-specific receptors enhances vaccine efficacy. DC-SIGN is a C-type lectin receptor that facilitates DC-specific delivery of Ag. This is accomplished by conjugating Ag to receptor-specific Ab or carbohydrate ligands that bind to its carbohydrate recognition domain. Here, we investigated the fate of DC-SIGN following receptor triggering with Ab. Both whole and single-chain Ab induced rapid internalization of about half of the surface receptor molecules. Biochemical studies showed that about half of the receptor molecules were still intracellular after 3 h, while minimal or no resurfacing of internalized or newly synthesized unbound DC-SIGN molecules was observed. Prolonged exposure of DCs to DC-SIGN Ab, but not carbohydrate ligands, resulted in reduced receptor expression levels, which lasted up to 2 days following removal of the Ab. In addition, exposure to DC-SIGN Ab reduced the ability of the receptor to internalize. Consequently, DC-SIGN showed a poor ability to accumulate targeting Abs within DCs. Vaccine efficacy may therefore be enhanced by strategies increasing the amount of Ag entering via a single receptor molecule, such as the use of targeting moieties allowing DC-SIGN recycling or Ab-coated vaccine carriers.     

两种气囊上滞留物引流方法对机械通气慢性阻塞性肺病患者呼吸机相关肺炎的预防

目的:探讨有创机械通气治疗的慢性阻塞性肺病(COPD)患者使用气囊上滞留物引流的干预措施能否有效减少COPD患者呼吸机相关肺炎(VAP)的发生率.比较持续囊上引流与间断囊上引流方法在预防VAP效果上的差异及患者耐受性.方法:选取入住我院RICU进行有创机械通气治疗的COPD患者,随机分成对照组、持续气囊上引流组(CSS...     

Antibody levels against tetanus and diphtheria after polychemotherapy for childhood sarcoma: a report from the Late Effects Surveillance System

Background

It is known that antineoplastic treatment may induce secondary immunodeficiency, but studies after childhood sarcoma are rare. Since 1998, the Late Effects Surveillance System (LESS) of the German Society for Paediatric Oncology and Haematology (GPOH) prospectively registers late effects in soft tissue-, osteo- and Ewing's sarcoma patients treated within the therapy trials EICESS-92/EURO-E.W.I.N.G.-99, CWS-96/CWS-2002P, COSS-96 in Austria, Germany and Switzerland.

Patients and methods

Antibody levels (AL) against diphtheria and tetanus were used as markers for immunity and classified according to established guidelines for protective AL values. There were 47 eligible relapse-free patients < 21 years of age (31 males; 10 osteosarcoma, 12 Ewing's and 25 soft tissue sarcoma patients). Median age at diagnosis was 9.6 (interquartile range: 4.4-14.7) years.

Results

A median 7.2 (3.7-12.2) months after end of antineoplastic therapy, in 28% (13/47; 95% CI 16-43%) of patients there were no protective AL (<0.1 IU/ml) against diphtheria and/or tetanus. Diphtheria and tetanus AL were positively correlated (r = 0.39; p = 0.007). In multivariable analysis, the type of treatment had no effect on AL, similar to tumour type and time of examination after treatment end. Younger patients had significantly lower AL against tetanus (p = 0.009) and girls had significantly lower AL against diphtheria than boys (p = 0.015).

Conclusion

Lack of protective AL against tetanus and/or diphtheria is frequent after childhood sarcoma treatment. Prospective surveillance of immunity and, if indicated, re-immunization is warranted in patients treated for childhood cancer.     

Hepatitis B virus markers among teenagers in the Araguaia region, Central Brazil: assessment of prevalence and vaccination coverage

The Brazilian hepatitis B (HBV) vaccination program for neonates was implemented in 1998 and broadened to include young people up to 20 years of age in 2001. However, HBV coverage of teenagers has not been systematically assessed in Brazil.A cross-sectional study was performed to estimate the magnitude of HBV infection and vaccine coverage among adolescent students regularly enrolled in the public schools of Barra do Garças, a city located in the state of Mato Grosso, Brazil. A representative sample was randomly obtained and participants were interviewed and had blood samples collected to test for HBV markers.The sample was composed of 576 subjects, 51% of which were females. The average age was 15, with the group ranging from 12 to 20 years of age. There were 29 anti-HBc reactive participants (5.0%). Four out of 29 were HBsAg positive (0.7%). Anti-HBs alone (vaccinated profile) showed in 323 (56.1%) students and 224 (38.9%) were negative for all HBV markers. Increasing age was associated with HBV exposure in a χ² for trend analysis (p = 0.004). The prevalence of anti-HBs alone decreased as the subjects’ age increased. Multivariate analysis showed independent association between HBV infection and the start of sexual activity. Another associated variable was the fact that the some students were enrolled in two low-income neighborhood schools.Our findings classify this area as low endemic for HBV and suggest that there is a progressive decrease in the spread of HBV in the region due to the introduction of universal vaccination of neonates. Approximately half of the adolescents 15 years or older were not immunized, which raises a concern in terms of the need to increase the vaccination rate for this segment of the population.     

Cooperative serum bactericidal activity between human antibodies to meningococcal factor H binding protein and neisserial heparin binding antigen

A meningococcal group B vaccine containing multiple protein antigens including factor H binding protein (fHbp) and Neisserial heparin binding antigen (NHba) is in clinical development. The ability of antibodies against individual antigens to interact and augment protective immunity is unknown. We assayed human complement-mediated bactericidal activity (SBA) in stored sera from six immunized adults before and after depletion of antibodies to fHbp and/or NHba. All six subjects developed ≥4-fold increases in SBA titer against a test strain with fHbp in the variant 1 group with an amino acid sequence that matched the vaccine antigen (GMT <1:4 baseline, to 1:139 after 3 doses of vaccine). By adsorption 88 to >95% of the SBA was directed against fHbp. Four subjects developed ≥4-fold increases in SBA titer against a test strain with a heterologous fHbp variant 2 antigen and a homologous NHba amino acid sequence that matched the vaccine antigen (GMT <1:4 baseline, to 1:45). SBA was directed primarily against NHba in one subject, against fHbp in a second, while depletion of either anti-NHba or anti-fHbp antibody removed the majority of SBA in sera from two subjects. In all four subjects, depletion of both anti-fHbp and anti-NHba antibodies removed more SBA than depletion of either antibody individually. Mixing a mouse non-bactericidal anti-fHbp variant 1 antiserum with a mouse anti-NHba antiserum also augmented the anti-NHba SBA titer against this test strain. For meningococcal vaccines that target relatively sparsely exposed antigens such fHbp or NHba, non-bactericidal antibodies against individual antigens can cooperate and elicit SBA.     

Primary care physician perspectives on providing adult vaccines

Recently, several new vaccines have been recommended for adults. Little is known regarding the immunization purchase and stocking practices of adult primary care physicians. To determine the proportion of family practice and internal medicine physicians who routinely stock specific adult vaccines and their rationale for those decisions, we conducted a cross-sectional survey in 2009 of a national random sample of 993 family physicians (FPs) and 997 general internists (IMs) in the US. Of the 1109 respondents, 886 reported that they provide primary care to adults aged 19-64 years and 96% of these physicians stock at least one vaccine recommended for adults. Of those, 2% plan to stop and 12% plan to increase vaccine purchases; the rest plan to maintain status quo. Of the respondents, 27% (31% FPs vs 20% IMs) stocked all adult vaccines. We conclude that many primary care physicians who provide care to adults do not stock all recommended immunizations. Efforts to improve adult immunization rates must address this fundamental issue.