Longitudinal Studies of Neutralizing Antibody Responses to Rotavirus in Stools and Sera of Children following Severe Rotavirus Gastroenteritis

Rotavirus-neutralizing antibody responses in sera and stools of children hospitalized with rotavirus gastroenteritis and then monitored longitudinally were optimally detected by using local rotavirus strains. Stool responses were highest on days 5 to 8 after the onset of diarrhea. Longitudinal monitoring suggested that serum neutralizing antibody responses were a more useful measure of severely symptomatic rotavirus infection than stool responses but that stool antibody responses may be a useful measure of rotavirus immunity.     

Development of Monoclonal Antibodies against Ureaplasma urealyticum Serotypes and Their Use for Serotyping Clinical Isolates

Monoclonal antibodies (MAbs) against Ureaplasma urealyticum serotype 2, 5, 7, 8, 10, 11, 12, and 13 reference strains were developed. The reactivities of these MAbs with the 14 serotype reference strains was verified by colony immunofluorescence assay and Western blot assay. MAbs against serotypes 2, 7, 10, 11, and 12 were serotype specific, whereas MAbs against serotypes 5, 8, and 13 showed cross-reactivity. All MAbs against serotype 5 were cross-reactive with serotype 2, and one showed, in addition, cross-reactivity to serotypes 9 and 10. Mutual cross-reactivities were observed between MAbs against serotypes 8 and 13. The usefulness of the MAbs for the serotyping of U. urealyticum strains was evaluated by serotyping 21 selected clinical isolates. A complete set of MAbs (the newly developed MAbs and the previously described MAbs against serotypes 1, 3, 4, 6, 9, and 14) as well as a complete set of polyclonal antibodies (PAbs), PAbs 1 to 14, were used. MAbs were able to identify 18 of 21 isolates including 2 isolates with mixed serotypes. Polyreactivity, which occurred with 19 of the 21 isolates with PAbs, was not observed by the use of MAbs. MAbs seem to be a more valuable tool than PAbs for serotyping and could help in investigating a possible link between the expression or variability of the serotype-specific antigens and pathogenicity.     

Lack of Maternal Antibodies to P Serotypes May Predispose Neonates to Infections with Unusual Rotavirus Strains

Rotavirus (RV) strains infecting newborns often have unique neutralization antigens (P serotypes) on their outer capsids that are distinct from those found on RV strains that cause diarrhea in older children. We examined the hypothesis that unusual RV strains preferentially infect newborns because the newborns lack maternal neutralizing antibodies to these strains. To test this hypothesis, sera and saliva samples collected from neonates infected with 116E-like (P[11]G9) strains in the maternity ward of the All India Institute of Medical Sciences (AIIMS) hospital in New Delhi were tested for neutralizing antibodies against common RV strains and those infecting newborns and these titers were compared with those of newborns who did not become infected (controls). The infected neonates had significantly lower levels of cord blood neutralizing antibodies to 116E than the controls, suggesting that immunity to neonatal RV infection is acquired transplacentally through maternal antibodies. Further, this study confirmed the immunogenicity of the AIIMS neonatal strain 116E, a vaccine candidate, in its ability to evoke a potent RV-specific immunoglobulin A and neutralizing antibody response in serum and saliva among the infected babies. Our findings have important implications for the development of an effective RV vaccine. In India, where G9 strains are common in the community, the use of 116E as a vaccine, together with the rhesus tetravalent vaccine, may provide a broader protection against all the circulating RV serotypes, including serotype G9, which is not represented in the current rhesus RV tetravalent vaccine (G1-G4).     

A Multiepitope Fusion Antigen Elicits Neutralizing Antibodies against Enterotoxigenic Escherichia coli and Homologous Bovine Viral Diarrhea Virus In Vitro

Diarrhea is one of the most important bovine diseases. Enterotoxigenic Escherichia coli (ETEC) and bovine viral diarrhea virus (BVDV) are the major causes of diarrhea in calves and cattle. ETEC expressing K99 (F5) fimbriae and heat-stable type Ia (STa) toxin are the leading bacteria causing calf diarrhea, and BVDV causes diarrhea and other clinical illnesses in cattle of all ages. It is reported that maternal immunization with K99 fimbrial antigens provides passive protection to calves against K99 fimbrial ETEC and that BVDV major structural protein E2 elicits antibodies neutralizing against BVDV viral infection. Vaccines inducing anti-K99 and anti-STa immunity would protect calves more effectively against ETEC diarrhea, and those also inducing anti-E2 neutralizing antibodies would protect calves and cattle against diarrhea caused by both ETEC and BVDV. In this study, we used the ETEC K99 major subunit FanC as a backbone, genetically embedded the STa toxoid STa_P12F and the most-antigenic B-cell epitope and T-cell epitope predicted from the BVDV E2 glycoprotein into FanC for the multivalent antigen FanC-STa-E2, and examined immunogenicity of this multivalent antigen to assess vaccine potential against bovine diarrhea. Mice intraperitoneally (i.p.) immunized with this multivalent antigen developed anti-K99, anti-STa, and anti-BVDV antibodies. Moreover, elicited antibodies showed neutralization activities, as they inhibited adherence of K99 fimbrial E. coli, neutralized STa toxin, and prevented homologous BVDV viral infection in vitro. Results from this study suggest that this multiepitope fusion antigen can potentially be developed as a vaccine for broad protection against bovine diarrhea and that the multiepitope fusion strategy may be generally applied for multivalent vaccine development against heterogeneous pathogens.     

Prevalence of Neutralizing Antibodies to Adenoviral Serotypes 5 and 35 in the Adult Populations of The Gambia, South Africa, and the United States

One of the major limitations of the use of adenoviruses as gene therapy vectors is the existence of preformed immunity in various populations. Recent studies have linked failure of adenoviral gene therapy trials to the presence of antiadenoviral neutralizing antibodies (NAb). Understanding the distribution and specificity of such antibodies will assist in the design of successful recombinant adenoviral gene therapies and vaccines. To assess the prevalence of NAb to adenovirus serotypes 5 and 35 (Ad5 and Ad35), we analyzed serum samples from adult immunocompetent individuals living in The Gambia, South Africa, and the United States by using a neutralization assay. Serum samples were incubated with A549 lung carcinoma cells and adenoviruses encoding enhanced green or yellow fluorescent proteins; results were analyzed by fluorescence microscopy and flow cytometry. Using this technique, we found a high prevalence of NAb against Ad5 in Gambian, South African, and U.S. subjects at both low and high titers. Conversely, all subjects displayed a low prevalence of NAb to Ad35; when present, anti-Ad35 NAb were seen at low titers. Because of the ability of adenoviruses to elicit systemic and mucosal immune responses, Ad35 with its low NAb prevalence appears to be an attractive candidate vector for gene therapy applications.     

Detection of Rotavirus Types G8 and G10 among Brazilian Children with Diarrhea

Characterization of 49 rotavirus-positive stool specimens from children with diarrhea in the state of Rio de Janeiro, Brazil, in 1996 and 1997 revealed a great diversity of rotavirus G types. Conventional types G1 and G3 accounted for 27 and 12% of the infections, respectively, whereas 60% of the infections were caused by unconventional types G5 (25%), G10 (16%), and G8 (4%) and mixed G types (16%).     

Prevalence of Enterotoxigenic Bacteroides fragilis in Children with Diarrhea in Japan

In age-matched controlled studies performed in Japan, enterotoxigenic Bacteroides fragilis was isolated from 14.9% of 114 children aged 1 to 14 years with antibiotic-unassociated diarrhea (AUD) and 6.5% of 108 children aged 1 to 6 years with antibiotic-associated diarrhea (AAD). The difference in comparison with control children, was significant for AUD children but not AAD children.     

Avidity of Antibodies against Infecting Pneumococcal Serotypes Increases with Age and Severity of Disease

The incidence of invasive pneumococcal disease (IPD) rises with age. Among adult IPD patients, the avidity of antipneumococcal polysaccharide antibodies against the infecting serotype increased with age and severity of disease, indicating that susceptibility to IPD in the elderly may rather be due to flaws in other aspects of opsonophagocytosis.     

Sleep and Skin Temperature in Preschool Children and Their Mothers

The purpose of this study was to investigate and compare sleep and skin temperature (Tsk) of preschool children with those of their mothers. The subjects included 18 pairs of preschool children and their mothers. The actigraphic measurement of sleep, Tsk, heart rate, bedroom climate, and the microclimate temperature and humidity (bed climate) were measured. Proximal and distal Tsk, the temperature gradient of distal and proximal Tsk (DPG), and bed climate temperature were significantly lower in the children. Approximately 70% of the children slept without bed covering. Heat dissipation during sleep in preschool children may primarily rely on the proximal Tsk. The lower Tsk than adults, and behavioral thermoregulation, may be important for sleep in preschoolers.     

Prevalence of Human Papillomavirus 16 and 18 Neutralizing Antibodies in Prenatal Women in British Columbia

Human papillomavirus (HPV) type 16 and 18 neutralizing antibody (NAb) titers were measured in 1,020 prenatal women in British Columbia aged 15 to 39. HPV 16 and 18 NAbs were detected in 183/1,020 (17.9%) and 97/1,020 (9.5%), respectively, and 39 (3.8%) had NAbs to both types. Titers were similar across age strata.Measurement of type-specific antibody responses to human papillomavirus (HPV) is important for seroprevalence estimates and assessment of vaccine efficacy. Vaccine manufacturers have developed enzyme immunoassays (EIAs) targeting neutralizing epitopes (3, 10), but neutralizing antibody (NAb) tests could be a suitable alternative because they confirm blocking of infection of susceptible cells and they potentially measure antibodies to more epitopes than existing manufacturers'' assays (13). Pseudovirus (PsV)-based NAb assays utilizing in vitro-generated HPV capsids containing a reporter plasmid have been described (1, 11). NAbs inhibit PsVs from infecting cells and from expressing the reporter plasmid product. For this study, we developed and validated a PsV NAb assay for HPV 16 and 18 and determined the seroprevalence among prenatal women in British Columbia (BC).HPV 16 and 18 PsVs were prepared as previously described (1), except that the reporter plasmid encoded red fluorescent protein (RFP) (11). Electron microscopic examination of the PsV preparations showed typical papillomavirus morphology. Bands at 55 kDa (capsid protein L1) and 70 kDa (capsid protein L2) were observed on Western blot analysis with rabbit antisera. Cesium chloride density gradient ultracentrifugation showed that over half of the PsV fraction had a buoyant density of approximately 1.34 g/ml, consistent with capsids containing DNA. PsVs were titrated in 293TT cells by monitoring the cultures for red fluorescent cells, with each fluorescent cell representing one infectious unit.NAb tests were performed as follows: sera were heated at 56°C for 30 min, and duplicate serial dilutions were prepared. Each serum dilution was mixed with 100 infectious units of the respective PsV and incubated for 1 h at 37°C, followed by transfer to 293TT cells on microtiter plates. Plates were incubated at 37°C and read after 4 to 6 days. The endpoint (100% neutralizing titer [NT₁₀₀]) was the highest dilution of serum which completely blocked cells displaying red fluorescence. Back-titrations of the PsV and serially diluted positive and negative serum controls were included in each run.For initial NAb test validation, five anti-HPV positive control sera (two against HPV 16, one against HPV 18, one against HPV 6, 11, 16, and 18, and one against HPV 6 and 11) and one anti-HPV negative control obtained from the National Institute for Biological Standards and Control (NIBSC), United Kingdom, were titrated. NAb titers corresponded with known antibody status (Table ​(Table1),1), although some were near the assay cutoff (1:40). Control sera for routine use were obtained from a volunteer 1 month after receiving a full course of Gardasil vaccine and from an HPV 16- and 18-seronegative volunteer.

TABLE 1.

HPV 16 and HPV 18 neutralizing antibody titers for NIBSC standard sera

学前儿童消极行为特征与母亲行为关系初探

目的：探讨学前儿童消极行为的基本状况及与母亲行为之间的关系。方法：采用儿童消极行为特征量表和母亲行为量表对742名3－6岁儿童的母亲进行了调查。结果：儿童消极行为特征不存在显著性别差异和年龄差异。儿童消极行为特征量表总分及各维度得分与母亲支持行为量表总分及各维度得分均呈显著负相关,儿童消极行为最多的是对父母过度要求,其次是注意分散、适应不良、消极情绪为最少的是对父母缺乏强化,但其在儿童消极行为特征较多的情况下,母亲所处的社会文化背景（城乡）、家庭收入、职业等因素对母亲的不支持行为有一定的影响。结论：（1）儿童消极行为特征越多,母亲对儿童的支持行为越少,不支持行为越多;（2）在儿童消极行为特征较多的情况下,改善儿童的抚养环境、提高母亲在儿童养育方面的知识水平是改善母亲行为、促进儿童健康发展的重要途径。     

Developmental Differences in Interactional Characteristics of Mothers and Their Children with Failure to Thrive

Observed interactional characteristics during feeding sessionsamong 68 pairs of low-income mother-child dyads. Half of thechildren were experiencing nonorganic failure to thrive (NOFTT)and half were growing adequately. Children were spoon-fed andranged in age from 8 to 26 months. Across NOFTT and comparisongroups, toddlers (13.5 to 26 months) were perceived by theirmothers as more difficult than were infants (8 to 13.4 months).Although there were few differences between the NOFTT and comparisongroups on interactional characteristics overall, mothers ofNOFTT toddlers were more hostile, intrusive, and less flexiblethan mothers of NOFTT infants and there was more tension andanger in their interactions. Maternal behavior did not differamong the comparison group. Mothers of NOFTT children may experiencedifficulties in responding to the increasing demands for autonomyduring feeding among toddlers. Finally, when the interactionwas observed in dyadic terms, toddlers in both groups tendedto be more active and involved than infants.     

Lack of Serum Antibodies against Borrelia burgdorferi in Children with Autism

It has been proposed that Borrelia burgdorferi infection is present in ∼25% of children with autism spectrum disorders. In this study, antibodies against Borrelia burgdorferi were assessed in autistic (n = 104), developmentally delayed (n = 24), and healthy control (n = 55) children. No seropositivity against Borrelia burgdorferi was detected in the children with and without autism. There was no evidence of an association between Lyme disease and autism.     

Dietary Rice Bran Protects against Rotavirus Diarrhea and Promotes Th1-Type Immune Responses to Human Rotavirus Vaccine in Gnotobiotic Pigs

Rice bran (RB) contains a distinct stoichiometry of phytochemicals that can promote gut mucosal immune responses against enteric pathogens. The effects of RB on rotavirus diarrhea and immunogenicity of an attenuated human rotavirus (HRV) vaccine were evaluated in gnotobiotic pigs. The four treatment groups studied were RB plus vaccine, vaccine only, RB only, and mock control. Pigs in the RB groups were fed the amount of RB that replaced 10% of the pigs'' total daily calorie intake from milk starting from 5 days of age until they were euthanized. Pigs in the vaccine groups were orally inoculated with two doses of the attenuated HRV vaccine. A subset of pigs from each group was orally challenged with the homologous virulent HRV on postinoculation day 28. Diarrhea and virus shedding were monitored daily from postchallenge day 0 to day 7. RB feeding significantly protected against diarrhea upon virulent HRV challenge and enhanced the protective rate of the vaccine against rotavirus diarrhea. Consistent with protection, RB significantly increased gamma interferon (IFN-γ)-producing CD4⁺ and CD8⁺ T cell responses in intestinal and systemic lymphoid tissues. Furthermore, RB also increased the number of total IgM- and IgA-secreting cells, total serum IgM, IgG, and IgA titers, and HRV-specific IgA titers in intestinal contents. RB reduced the numbers of intestinal and systemic HRV-specific IgA and IgG antibody-secreting cells and reduced serum HRV-specific IgA and IgG antibody titers before the challenge. These results demonstrate clear beneficial effects of RB in protection against rotavirus diarrhea and stimulation of nonspecific and HRV-specific immune responses, as well as its biased Th1-type adjuvant effect for the vaccine.     

Development, Characterization, and Diagnostic Applications of Monoclonal Antibodies against Bovine Rotavirus

Hybridomas secreting monoclonal antibodies (MAbs) against the Nebraska calf diarrhea strain of bovine rotavirus (BRV) were characterized. Indirect fluorescent-antibody assay, immunodot assay, and immunoprecipitation were used to select hybridomas that produced anti-BRV MAbs. Seven of the MAbs were shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot assay to be reactive with the BRV outer capsid protein, VP7, which has a molecular mass of 37.5 kDa. None of the seven MAbs were reactive with canine rotavirus, bovine coronavirus, or uninfected Madin-Darby bovine kidney cells. Two clones, 8B4 (immunoglobulin G2a [IgG2a]) and 2B11 (IgG1), were found suitable for use in an antigen capture enzyme-linked immunosorbent assay for detecting BRV in bovine fecal samples. Both were subtype A specific (G6 subtype) but did not react with all isolates of BRV group A.     

Vaccination of Rabbits with an Alkylated Toxoid Rapidly Elicits Potent Neutralizing Antibodies against Botulinum Neurotoxin Serotype B

New Zealand White (NZW) rabbits were immunized with several different nontoxic botulinum neurotoxin serotype B (BoNT/B) preparations in an effort to optimize the production of a rapid and highly potent, effective neutralizing antibody response. The immunogens included a recombinant heavy chain (rHc) protein produced in Escherichia coli, a commercially available formaldehyde-inactivated toxoid, and an alkylated toxoid produced by urea-iodoacetamide inactivation of the purified active toxin. All three immunogens elicited an antibody response to BoNT/B, detected by enzyme-linked immunosorbent assay (ELISA) and by toxin neutralization assay, by the use of two distinct mouse toxin challenge models. The induction period and the ultimate potency of the observed immune response varied for each immunogen, and the ELISA titer was not reliably predictive of the potency of toxin neutralization. The kinetics of the BoNT/B-specific binding immune response were nearly identical for the formaldehyde toxoid and alkylated toxoid immunogens, but immunization with the alkylated toxoid generated an approximately 10-fold higher neutralization potency that endured throughout the study, and after just 49 days, each milliliter of serum was capable of neutralizing 10⁷ 50% lethal doses of the toxin. Overall, the immunization of rabbits with alkylated BoNT/B toxoid appears to have induced a neutralizing immune response more rapid and more potent than the responses generated by vaccination with formaldehyde toxoid or rHc preparations.Botulinum neurotoxin (BoNT), the causative agent of botulism, is the most potent of all the known toxins (7). BoNT is a secreted protein produced by the anaerobic soil organisms Clostridium botulinum, Clostridium baratii, and Clostridium butyricum in seven distinct serotypes (serotypes A to G) (9, 23, 28). The BoNT serotypes are all synthesized as single-chain polypeptides with molecular masses of approximately 150 kDa. Posttranslational cleavage of the original polypeptide monomer results in the formation of a disulfide-linked dichain product composed of light chain (LC) and heavy chain (HC) domains. The HC is divided into two distinct functional domains; the first mediates toxin binding and uptake by peripheral neuronal cells, and the second mediates translocation of the LC subunit into the target cell cytosol. Once it is in the cytosol, the zinc metalloprotease of the LC specifically cleaves the soluble N-ethylmaleimide-sensitive factor (NSF) attachment protein receptors (SNAREs) responsible for synaptic vesicle docking and neurotransmitter release at the neuromuscular synapse.Human botulism typically results from the ingestion of contaminated foods (often improperly prepared canned goods), although BoNT intoxication can also result from wound colonization by one or more species of Clostridium. Similarly, infant botulism results from exposure to actively secreted toxin following the germination of ingested Clostridium spores, which proliferate in the immature gastrointestinal tract. Regardless of the route of exposure, BoNT intoxication occurs by the same mechanism, once the toxin enters the circulation. Although there is no cure for botulism after the onset of symptoms, an effective circulating antibody response can completely neutralize an otherwise intoxicating dose of BoNT. Widespread immunization against the toxin is precluded by the growing number of clinical applications of BoNT for the treatment of various neuromuscular spasticity disorders, yet BoNT vaccine development continues for the purposes of immunizing at-risk populations, such as laboratory workers, first responders, and military personnel (26).A number of BoNT immunogens and a variety of vaccination strategies have successfully been used to elicit neutralizing antibody responses against individual BoNT serotypes (3, 19, 20, 29, 32). The immune responses to BoNT vary according to the animal species, the toxin serotype, and the antigen preparation. Additionally, the development of a potent neutralizing antibody response to BoNT serotype B (BoNT/B) has proven problematic, prompting a demand for alternative toxin-derived immunogens (25, 27).In the present study, we tested three BoNT/B immunogens in New Zealand White (NZW) rabbits using a rapid vaccination scheme to develop a potent toxin-neutralizing immune response in a short time period (12). Rabbits were immunized with BoNT/B recombinant heavy chain (rHc) or toxoid preparations derived from formaldehyde inactivation or urea- iodoacetamide alkylation of active toxin (15). All three immunogens elicited toxin-neutralizing antibody responses by the end of the study; however, vaccination with the alkylated toxoid preparation induced a more rapid and more potent BoNT/B-neutralizing response than the other immunogens.     

诺如病毒与轮状病毒所致的110例婴幼儿急性腹泻病例临床特征分析

目的 对诺如病毒与轮状病毒所致婴幼儿急性腹泻的临床特点进行分析探讨.方法 收集2010年1月-2015年3月间病毒性婴幼儿急性腹泻患者110例临床资料进行回顾性分析,按照病原学检测情况分为诺如病毒组51例及轮状病毒组59例.另取45例细菌感染所致急性腹泻患儿作为对照组.对诺如病毒与轮状病毒所致婴幼儿急性腹泻的实验室检查、临床症状以及流行病学特征进行分析比较.结果 诺如病毒组患者与轮状病毒组患者在各项实验室检查及临床症状方面均无统计学差异(P＞0.05),但与对照组相比均有统计学差异(P＜0.05).两组病毒均易感小于2岁的患儿,其中诺如病毒组患儿年龄在13-24个月中所占全部患儿比例为17.65％、轮状病毒组为35.59％,两者比较差异有统计学意义(P＜0.05).诺如病毒及轮状病毒组患儿集中检出月份均为11月、12月及1月.结论 诺如病毒与轮状病毒感染所致的婴幼儿急性腹泻在实验室检查、临床特点以及流行情况差异均不显著,为明确诊断,需进行病原学实验室检查.     

Development and Optimization of a High-Throughput Assay To Measure Neutralizing Antibodies against Clostridium difficile Binary Toxin

Clostridium difficile strains producing binary toxin, in addition to toxin A (TcdA) and toxin B (TcdB), have been associated with more severe disease and increased recurrence of C. difficile infection in recent outbreaks. Binary toxin comprises two subunits (CDTa and CDTb) and catalyzes the ADP-ribosylation of globular actin (G-actin), which leads to the depolymerization of filamentous actin (F-actin) filaments. A robust assay is highly desirable for detecting the cytotoxic effect of the toxin and the presence of neutralizing antibodies in animal and human sera to evaluate vaccine efficacy. We describe here the optimization, using design-of-experiment (DOE) methodology, of a high-throughput assay to measure the toxin potency and neutralizing antibodies (NAb) against binary toxin. Vero cells were chosen from a panel of cells screened for sensitivity and specificity. We have successfully optimized the CDTa-to-CDTb molar ratio, toxin concentration, cell-seeding density, and sera-toxin preincubation time in the NAb assay using DOE methodology. This assay is robust, produces linear results across serial dilutions of hyperimmune serum, and can be used to quantify neutralizing antibodies in sera from hamsters and monkeys immunized with C. difficile binary toxin-containing vaccines. The assay will be useful for C. difficile diagnosis, for epidemiology studies, and for selecting and optimizing vaccine candidates.     

Association of Providencia alcalifaciens with Diarrhea in Children

It has been demonstrated in previous studies that Providencia alcalifaciens can produce diarrhea by an invasive mechanism. In the present study, P. alcalifaciens was isolated from the stool specimens of 17 of 814 diarrheal children younger than 5 years of age (2.1%) and from those of 4 of 814 matched controls (0.49%) (P = 0.004), indicating that the organism is significantly associated with diarrhea. However, 71% of P. alcalifaciens-positive diarrheal children had simultaneous infections with other recognized enteric pathogens.