Serotype-specific Antibodies Research Articles

Establishment and Comparison of Two Different Diagnostic Platforms for Detection of DENV1 NS1 Protein.

Dengue virus (DENV) infection is currently at pandemic levels, with populations in tropical and subtropical regions at greatest risk of infection. Early diagnosis and management remain the cornerstone for good clinical outcomes, thus efficient and accurate diagnostic technology in the early stage of the disease is urgently needed. Serotype-specific monoclonal antibodies (mAbs) against the DENV1 nonstructural protein 1 (NS1), DA12-4, DA13-2, and DA15-3, which were recently generated using the hybridoma technique, are suitable for use in diagnostic platforms. Immunofluorescence assay (IFA), enzyme-linked immunosorbent assay (ELISA) and Western blot analysis further confirmed the serotype specificity of these three monoclonal antibodies. The ELISA-based diagnostic platform was established using the combination of two highly sensitive mAbs (DA15-3 and DB20-6). The same combination was also used for the flow cytometry-based diagnostic platform. We report here the detection limits of flow cytometry-based and ELISA-based diagnostic platforms using these mAbs to be 0.1 and 1 ng/mL, respectively. The collected clinical patient serum samples were also assayed by these two serotyping diagnostic platforms. The sensitivity and specificity for detecting NS1 protein of DENV1 are 90% and 96%, respectively. The accuracy of our platform for testing clinical samples is more advanced than that of the two commercial NS1 diagnostic platforms. In conclusion, our platforms are suitable for the early detection of NS1 protein in DENV1 infected patients.

Response to pneumococcal polysaccharide vaccination in patients with chronic and allergic aspergillosis

IntroductionPneumococcal infection causes significant morbidity in patients with underlying lung disease, and vaccination has been associated with reduced disease rates. Response to vaccination has not been studied in chronic lung conditions characterised by ongoing infection or inflammation like chronic pulmonary aspergillosis (CPA). MethodsIn a prospective observational study, consecutive patients with CPA, allergic aspergillosis and bronchiectasis attending a national referral centre received pneumococcal 23-valent polysaccharide vaccine (PPV-23) and had pre- and post-vaccination antibody concentrations quantified as part of routine clinical care. Serotype-specific pneumococcal IgG antibodies were quantified for 12 serotypes using a multiplex microsphere assay. A protective response was defined as a level of >1.3μg/mL or a ≥ fourfold rise in concentration for ≥70% of serotypes, pre to post-vaccination. C-reactive protein, Immunoglobulins and mannose binding lectin (MBL) levels were measured and correlated to vaccine response. ResultsA total of 318 patients were enrolled. In vaccine-naïve patients (n=127), the lowest pre-vaccination levels were seen with serotypes 1 and 4 and the highest with serotype 19A. A protective response post-vaccination was seen in 50% of patients. The poorest responses were observed with serotypes 1, 3 and 4. Levels of C-reactive protein did not affect efficacy. Profound MBL deficiency was found in 28.8%; there were no significant differences in response to vaccination in patients with or without MBL deficiency. Post-vaccination serotype-specific concentrations waned gradually, however they were still elevated compared to pre-vaccination after 2–5 years. ConclusionsPatients with chronic and allergic aspergillosis exhibited a poor response to PPV-23 vaccination compared to healthy adults. An alternative vaccination strategy or delay of vaccination until their underlying condition is better controlled, e.g. after treatment with antifungals may result in better response.

Correlates of protection of serotype-specific capsular antibody and invasive Group B Streptococcus disease in South African infants

BackgroundVaccinating pregnant women may prevent invasive Group B Streptococcus (GBS) disease in their young infants. In a low-middle income setting, we sought to determine an association between natural maternal antibody responses and the development of invasive GBS disease. MethodsWe undertook a matched case-control study in Johannesburg, South Africa. Maternal and infant antibody concentrations were compared between serotype-specific Ia and III GBS cases and well-baby controls in which the mother was colonized with the same serotype. ResultsThe median maternal serotype Ia and III antibody concentrations (in μg/mL) were 0.05 (IQR: 0.02–0.24; n=27) and 0.14 (IQR: 0.08–0.33; n=29) in cases, and 0.29 (IQR: 0.06–1.60; n=43) and 0.29 (IQR: 0.13–0.58; n=31) in homotypic controls, respectively. A smaller proportion of cases as compared to homotypic controls had higher serotype Ia and III maternal antibody concentrations. Using Bayesian modeling, we demonstrated that the risk of invasive GBS disease was less than 10% with maternal antibody concentrations ≥6μg/mL and ≥3μg/mL for serotypes Ia and III, respectively. ConclusionsMaternal capsular antibody concentrations are associated with the risk of invasive GBS disease in infants. In a low-middle income setting with a high burden of invasive disease, we have demonstrated a sero-correlate of protection for GBS serotypes Ia and III which could facilitate vaccine licensure.

Functional immune responses to twelve serotypes after immunization with a 23-valent pneumococcal polysaccharide vaccine in older adults

BackgroundThe 23-valent pneumococcal polysaccharide vaccine (PPSV23) was introduced as part of the national immunization program for the elderly (≥65 years of age) in Korea on 2013. To evaluate immune responses in this population, serotype-specific anti-pneumococcal antibodies were studied with opsonophagocytic assay (OPA). MethodsPneumococcal vaccine-naïve participants ≥65 years of age were enrolled. They were divided into two groups according to their age: 30 in (65–74 years) and 32 in group (≥75 years). The functional antibody response was determined by multiplexed OPA (MOPA) for 12 serotypes (1, 3, 4, 5, 6B, 7F, 9V, 14, 18C, 19A, 19F, and 23F) before and 4 weeks after vaccination with PPSV23. ResultsGeometric mean titers (GMTs) to all tested serotypes significantly increased in both groups after vaccination compared to those before vaccination. There were no significant differences in either the fold rise (post-vaccination to pre-vaccination) or the percentage of participants with a ≥4-fold increase in OPA titers between two groups for any of the 12 serotypes. Following vaccination, GMT for serotype 9V was higher in group 1 than in group 2 (P=0.011). ConclusionsPPSV23 induces functional immune response for 12 vaccine serotypes in both age groups. Further analysis is needed for the remaining 11 serotypes in the PPSV23, in order to develop a better understanding of the immune responses induced by PPV23 in older adults.

Functional immune responses to 11 non-PCV13 serotypes after immunization with a 23-valent pneumococcal polysaccharide vaccine in older adults.

The 23-valent pneumococcal polysaccharide vaccine (PPSV23) has been recommended for adults aged ≥65years. To evaluate functional immune response against the additional 11 serotypes that are included in PPSV23, but not the 13-valent pneumococcal conjugate vaccine (PCV13), serotype-specific anti-pneumococcal antibodies were examined using an opsonophagocytic assay (OPA). Participants ≥65years of age that were naïve to the pneumococcal vaccine were enrolled. They were divided into two groups according to their age: group 1 (N=30; aged 65-74years) and group 2 (N=32; aged ≥75years). The functional antibody response prior to and 4weeks post-immunization with PPSV23 was determined, using a multiplexed OPA (MOPA) for 11 pneumococcal serotypes (2, 8, 9N, 10A, 11A, 12F, 15B, 17F, 20B, 22F, and 33F). Geometric mean OPA titers (GMTs) to 11 serotypes were significantly increased in both groups post-immunization compared to those prior to immunization. The GMTs for all serotypes were not significantly different between the two groups after immunization. The proportion of subjects with OPA titers post-immunization of ≥8 and ≥64 was 93-100% and 80-100% for the 11 serotypes, respectively, while subjects with a ≥4-fold increase in OPA titers ranged from 9 to 90% for the 11 serotypes. This study revealed that PPSV23 vaccination induced significant functional immune responses to 11 non-PCV13 serotypes in older adults. The MOPA has been shown to be a useful tool for future application in evaluating new PCVs in older adults. The clinical trial registration number is KCT 0001963 (CRIS, https://cris.nih.go.kr/cris/en/).

Reduced IL-17A Secretion Is Associated with High Levels of Pneumococcal Nasopharyngeal Carriage in Fijian Children.

Streptococcus pneumonia (the pneumococcus) is the leading vaccine preventable cause of serious infections in infants under 5 years of age. The major correlate of protection for pneumococcal infections is serotype-specific IgG antibody. More recently, antibody-independent mechanisms of protection have also been identified. Preclinical studies have found that IL-17 secreting CD4+ Th17 cells in reducing pneumococcal colonisation. This study assessed IL-17A levels in children from Fiji with high and low pneumococcal carriage density, as measured by quantitative real-time PCR (qPCR). We studied Th17 responses in 54 children who were designated as high density carriers (N=27, >8.21x105 CFU/ml) or low density carriers (N=27, <1.67x105 CFU/ml). Blood samples were collected, and isolated peripheral blood mononuclear cells (PBMCs) were stimulated for 6 days. Supernatants were harvested for cytokine analysis by multiplex bead array and/or ELISA. Th17 cytokines assayed included IL-17A, IL-21, IL-22 as well as TNF-α, IL-10, TGF-β, IL-6, IL-23 and IFNγ. Cytokine levels were significantly lower in children with high density pneumococcal carriage compared with children with low density carriage for IL-17A (p=0.002) and IL-23 (p=0.04). There was a trend towards significance for IL-22 (p=0.057) while no difference was observed for the other cytokines. These data provide further support for the role of Th17-mediated protection in humans and suggest that these cytokines may be important in the defence against pneumococcal carriage.

Anti-Pneumococcal Capsular Polysaccharide Antibody Response and CD5 B Lymphocyte Subsets.

The role of CD19(+) CD5(+) and CD19(+) CD5(-) B cell subpopulations in the antibody response to pneumococcal capsular polysaccharides (caps-PSs) is controversial. In the present study, we evaluated the role of human CD19(+) CD5(+) and CD19(+) CD5(-) cell populations in the serotype-specific antibody response to caps-PS. After vaccination of 5 healthy human adults with Pneumovax (23-valent pneumococcal polysaccharide vaccine [PPV23]), IgG anti-caps-PS serotype 4 antibody-producing cells resided mainly in the CD19(+) CD5(-) B cell subset, as assessed by enzyme-linked immunosorbent spot (ELISpot) analysis. Moreover, in a humanized SCID mouse model, CD19(+) CD5(-) B cells were more effective than CD19(+) CD5(+) cells in producing IgG anti-cap-PS antibodies. Finally, an association was found between the level of IgG anti-caps-PS antibodies and the number of CD19(+) CD5(-) B cells in 33 humans vaccinated with PPV23. Taken together, our data suggest that CD5 defines a functionally distinct population of B cells in humans in the anti-caps-PS immune response.

112. A Novel Oncolytic Adenovirus Based on Human Adenovirus Serotype 17

Most existing oncolytic adenoviruses (AdV) are based on human AdV type 5 from species C (hAdV-C5). Clinical efficacy of hAdV-C5 based oncolytic viruses is limited by variable expression levels of coxsackie- and adenovirus receptor (CAR) in different tumour cells and insufficient replication rates. Additionally, patients exposed to AdV develop serotype specific neutralizing antibodies compromising reapplication. Thus, development of novel oncolytic AdV based on other serotypes may help overcoming these limitations. It may additionally allow repeated dosing in humans and add to the repertoire of antitumour agents in general. We further hypothesised that oncolytic efficacy of the candidate virus can be augmented by expression of RNAi suppressor protein P19 (Lecellier et al., Nature 2005) as has been shown previously for hAdV-C5 (Rauschhuber et al, Sci. Rep. 2013). Based on a computational model AdV of species D including type 17 (hAdV-D17) are predicted to have the highest probability of expressing pre-miRNA compared to other group AdV (Pfeffer et al, Nat. Methods 2005). Moreover, high infection efficiency of EA.hy926 cells, a vascular endothelium tumor cell line that lacks CAR (Jing Liu, unpublished) with AdV17 as well as absence of cross-reactivity with AdVC5 may allow exploitation for AdV-C5-insensitive tumors and systemic therapy. Here we aim at evaluating a novel hAdV-D17-based, p19-containing oncolytic AdV as novel candidate for oncolytic applications in different major tumour cell lines and for toxicity in non-malignant cells. Thus, we cloned hAdV-17 and a P19-containing hAdV-D17 based virus by a novel seamless recombineering technique (Zhang et al, unpublished). In order to allow P19 expression from the adenoviral vector genome, the P19 cDNA was fused via an internal ribosome entry site (IRES) to the late fiber gene. To obtain control viruses, GFP was fused via an IRES to the late fiber gene. After release of the respective recombinant adenoviral genomes from plasmids containing the complete DNA molecule, linearized viral DNA was transfected into A549 cells to perform rescue experiments. To evaluate oncolytic potential we are currently comparing it with wild-type hAdV-D17 and hAdV-C5 using common oncolytic essays. Evaluation in primary tumour cells and eventually in an animal model will allow making assumptions about feasibility of oncolytic virotherapy with this vector. In total we believe that HAdV17-based vectors hold promise for oncolytic applications and may be improved by RNAi-suppression.

Antibody Response is More Likely to Pneumococcal Proteins Than to Polysaccharide After HIV-associated Invasive Pneumococcal Disease

Human immunodeficiency virus (HIV)-infected individuals are at increased risk of invasive pneumococcal disease (IPD). In order to assess the immunogenicity of pneumococcal proteins and polysaccharide, we investigated protein and serotype-specific antibody responses after HIV-associated IPD. Specific antipneumococcal immunoglobulin G to 27 pneumococcal protein antigens and 30 serotype polysaccharides was measured in plasma before and after IPD in HIV-infected individuals and compared to HIV-infected individuals without IPD. Over time, 81% of IPD cases responded to at least 1 protein compared to 51% of non-IPD controls. HIV IPD cases responded to more proteins than non-IPD controls (8.6 ± 8.4 vs 4.2 ± 7.6 proteins; P = .01), and had a significantly higher probability of yielding an antibody response to the proteins PiaA, PsaA, and PcpA. Twenty-two percent of HIV-infected individuals with IPD had a serotype-specific antibody response. Younger age at the time of IPD was the only predictor of a serotype-specific pneumococcal antibody response, whereas we did not identify predictors of a protein-specific antibody response. Antibody responses occurred more frequently to pneumococcal proteins than to polysaccharide, and protein antibodies persisted for longer than polysaccharide-specific antibodies. PcpA, PiaA, and PsaA were the most immunogenic proteins.

Occurrence of Foot and Mouth Disease serotypes in trade cattle sold in Kwara state, Nigeria

Aims: Serological detection of Foot and Mouth Disease Virus (FMDV) serotype specific antibodies in trade cattle was conducted to determine occurrence of FMDV serotypes. Methodology and results: Cross-sectional study based on randomly sampled sera in cattle with unknown FMD vaccination history was carried out in five cattle markets in Kwara state over a period of 3 months (August-SeptemberOctober) in 2011. The sera were screened for antibodies to FMDV non-structural protein (NSP) using NS-Blocking ELISA Kit (PrioCHECK®) and serotype specific antibodies determined by a Solid-Phase Competitive ELISA. Out of 253 sera positive for FMDV serotypes, 74.3% (188) sera were from recovered and 25.7% (65 sera) infected trade cattle. The percentage serotype distribution was 18.6%, 46.6%, 21.3%, and 13.4% for serotype A, O, SAT1 and SAT2 respectively. However, combination of O and A, A and SAT2 as well as O and SAT2 occurred in some cattle. Serotype distribution according to location showed serotype O and SAT2 was highest in Ajasse and serotype A and SAT1 was highest in Bode Sadu and Ilesha baruba markets respectively. Conclusion, significance and impact study: Specific antibody detection confirmed FMD serotypes endemicity and ongoing infections in trade cattle within the Nigerian local markets. The identification of these circulating FMDV serotypes is necessary as a baseline for vaccination control strategy, in conjunction with international livestock trade regulation to enhance potentials of national dependence on beef exportation.

Vaccination status and immune response to 13-valent pneumococcal conjugate vaccine in asplenic individuals

Overwhelming post-splenectomy infection (OPSI) is immediately life-threatening and vaccination against encapsulated bacteria, in particular pneumococci, decreases its incidence.First, we investigated the adherence to vaccination guidelines in a retrospective study of the hospital records of splenectomised patients. Second, patients were asked to complete a questionnaire and invited to participate in a study where 12-valent pneumococcal serotype-specific IgG concentrations were determined before and 4 to 6 weeks after vaccination with PCV13.Of 79 individuals who underwent splenectomy between 2000 and 2012: 81.0% received pneumococcal vaccine, 51.9% received vaccine against Haemophilus influenzae type B and 22.8% received meningococcal vaccine. 31 individuals were deceased. 33 individuals completed questionnaires and accepted participation in the second part of the study. The participants consisted of two groups: (1) prior PPV23 (n=24) and (2) prior PPV23+PCV13 (n=9). In group 1, pre-PCV13 GMC's≥0.35μg/mL were observed for serotypes 1, 4, 6B, 7F, 9V, 14, 18C, 19A, 19F and 23F, and GMC's<0.35μg/mL for serotypes 3 and 5, significant increases pre- to post-PCV13 were found for serotypes 1, 3, 4, 5, 7F, 18C, 19A, 23F (p≤0.001) and 19F (p=0.01) and all 12 serotypes-specific GMC were above 0.35μg/mL after vaccination. Group 2 did not receive vaccine in this study, but blood tests showed all 12 serotype-specific GMC>0.35μg/mL.Adherence to guidelines regarding primary pneumococcal vaccination was adequate but only a minority received the recommended meningococcal vaccination.High levels of pneumococcal serotype-specific antibodies were observed in the previous PPV23 vaccinated group, and more pronounced in the previous PCV13 group, and our data suggests that PCV13 is immunogenic for serotypes 1, 3, 4, 5, 7F, 18C, 19A, 19F and 23F, if used as a booster dose in asplenic patients with previous PPV23 vaccination.

Natural acquired humoral immunity against serotype-specific group B Streptococcus rectovaginal colonization acquisition in pregnant women

Group B Streptococcus (GBS) rectovaginal colonization in pregnant women is associated with invasive GBS disease in newborns, preterm delivery and stillbirths. We studied the association of GBS serotype-specific capsular polysaccharide (CPS) antibody on new acquisition and clearance of rectovaginal GBS colonization in pregnant women from 20 weeks until 37 to 40 weeks' gestation. Serum serotype-specific CPS IgG antibody concentration was measured by multiplex enzyme-linked immunosorbent assay and opsonophagocytic activity (OPA) titres. Rectovaginal swabs were evaluated for GBS colonization, using standard culture methods and serotyping by latex agglutination, at five to six weekly intervals. Higher serotype III CPS antibody concentration was associated with lower risk of rectovaginal acquisition of serotype III during pregnancy (p 0.009). Furthermore, serotype-specific OPA titres to Ia and III were higher in women who remained free of GBS colonization throughout the study compared to those who acquired the homotypic serotype (p <0.001 for both serotypes). Serum CPS IgG values of ≥1μg/mL for serotype V and ≥3μg/mL for serotypes Ia and III were significantly associated with protection against rectovaginal acquisition of the homotypic serotype. A GBS vaccine that induces sufficient capsular antibody in pregnant women, including high OPA titres, could protect against rectovaginal colonization during the latter half of pregnancy.

Recognition determinants of broadly neutralizing human antibodies against dengue viruses.

Dengue disease is caused by four different flavivirus serotypes, which infect 390million people yearly with 25% symptomatic cases and for which no licensed vaccine is available. Recent phase III vaccine trials showed partial protection, and in particular no protection for dengue virus serotype 2 (refs 3, 4). Structural studies so far have characterized only epitopes recognized by serotype-specific human antibodies. We recently isolated human antibodies potently neutralizing all four dengue virus serotypes. Here we describe the X-ray structures of four of these broadly neutralizing antibodies in complex with the envelope glycoprotein E from dengue virus serotype 2, revealing that the recognition determinants are at a serotype-invariant site at the E-dimer interface, including the exposed main chain of the E fusion loop and the two conserved glycan chains. This 'E-dimer-dependent epitope' is also the binding site for the viral glycoprotein prM during virus maturation in the secretory pathway of the infected cell, explaining its conservation across serotypes and highlighting an Achilles' heel of the virus with respect to antibody neutralization. These findings will be instrumental for devising novel immunogens to protect simultaneously against all four serotypes of dengue virus.

The FACT score in predicting pneumococcal antibody levels in asthmatics

Background: There is no measure currently available to identify asthmatics with potential immune incompetence. Objective: We propose use of a novel scoring system called the FACT score, which is formulated based on four parameters: (1) Family history of asthma, (2) Atopic conditions, (3) Bacterial colonization and (4) Th1 versus Th2 immune profile. Methods: This was a cross-sectional study involving 16 asthmatics and 14 non-asthmatics. The first two parameters of the FACT score were obtained via a chart review and interview. For the third parameter, nasopharyngeal swab samples were cultured. The ratio of interleukin-5 to interferon-gamma for each patient was measured by peripheral blood mononuclear cells cultured with house dust mite. Antibodies to 23 pneumococcal antigens were used for humoral immunity. Results: The FACT scores for asthmatics (mean ± SD: 5.2 ± 1.87) were higher than those for non-asthmatics (mean ± SD: 3.3 ± 1.5) (p = 0.008). Of the 16 asthmatics, 7 (44%) had 12 or more positive serotype-specific polysaccharide antibodies, whereas 12 of 14 (86%) of non-asthmatics subjects had 12 or more positive serotype-specific polysaccharide antibodies (p = 0.014). Overall, the FACT score was inversely correlated with the number of positive serotype-specific antibody levels [rho (ρ) = -0.38, p = 0.04]. The proportions of subjects with 12 or more positive serotype-specific antibodies among non-asthmatics and asthmatics below and above the median of the FACT scores were 86, 50 and 38%, respectively (p = 0.052). Conclusions: The FACT score may help us identify a subset of asthmatics with immune incompetence. Study findings need to be replicated in a larger study.

Association between serotype-specific antibody response and serotype characteristics in patients with pneumococcal pneumonia, with special reference to degree of encapsulation and invasive potential.

We studied the immunoglobulin (Ig) response to causative serotype-specific capsular polysaccharides in adult pneumococcal pneumonia patients. The serotypes were grouped according to their degree of encapsulation and invasive potential. Seventy patients with pneumococcal pneumonia, 20 of whom were bacteremic, were prospectively studied. All pneumococcal isolates from the patients were serotyped, and the Ig titers to the homologous serotype were determined in acute- and convalescent-phase sera using a serotype-specific enzyme-linked immunosorbent assay. The Ig titers were lower in bacteremic cases than in nonbacteremic cases (P < 0.042). The Ig titer ratio (convalescent/acute titer) was ≥2 in 33 patients, 1 to 1.99 in 20 patients, and <1 in 17 patients. Patients ≥65 years old had a lower median Ig titer ratio than did younger patients (P < 0.031). The patients with serotypes with a thin capsule (1, 4, 7F, 9N, 9V, and 14) and medium/high invasive potential (1, 4, 7F, 9N, 9V, 14, and 18C) had higher Ig titer ratios than did patients with serotypes with a thick capsule (3, 6B, 11A, 18C, 19A, 19F, and 23F) and low invasive potential (3, 6B, 19A, 19F, and 23F) (P < 0.05 for both comparisons after adjustment for age). Ig titer ratios of <1 were predominantly noted in patients with serotypes with a thick capsule. In 8 patients with pneumococcal DNA detected in plasma, the three patients with the highest DNA load had the lowest Ig titer ratios. In conclusion, a high antibody response was associated with serotypes with a thin capsule and medium/high invasive potential, although a low antibody response was associated with serotypes with a thick capsule and a high pneumococcal plasma load.

Epidemiology of Bluetongue in India.

Bluetongue (BT) is an insectborne endemic disease in India. Although infections are observed in domestic and wild ruminants, the clinical disease and mortality are observed only in sheep, especially in the southern states of the country. The difference in disease patterns in different parts of the country could be due to varied climatic conditions, sheep population density and susceptibility of the sheep breeds to BT. Over the five decades after the first report of BT in 1964, most of the known serotypes of bluetongue virus (BTV) have been reported from India either by virus isolation or by detection of serotype-specific antibodies. There have been no structured longitudinal studies to identify the circulating serotypes throughout the country. At least ten serotypes were isolated between 1967 and 2000 (BTV-1-4, 6, 9, 16-18, 23). Since 2001, the All-India Network Programme on Bluetongue and other laboratories have isolated eight different serotypes (BTV-1-3, 9, 10, 12, 16, 21). Genetic analysis of these viruses has revealed that some of them vary substantially from reference viruses, and some show high sequence identity with modified live virus vaccines used in different parts of the world. These observations have highlighted the need to develop diagnostic capabilities, especially as BT outbreaks are still declared based on clinical signs. Although virus isolation and serotyping are the gold standards, rapid methods based on the detection of viral nucleic acid may be more suitable for India. The epidemiological investigations also have implications for vaccine design. Although only a handful serotypes may be involved in causing outbreaks every year, the combination of serotypes may change from year to year. For effective control of BT in India, it may be pertinent to introduce sentinel and vector traps systems for identification of the circulating serotypes and to evaluate herd immunity against different serotypes, so that relevant strains can be included in vaccine formulations.

Dengue serotype cross-reactive, anti-e protein antibodies confound specific immune memory for 1 year after infection.

Dengue virus has four serotypes and is endemic globally in tropical countries. Neither a specific treatment nor an approved vaccine is available, and correlates of protection are not established. The standard neutralization assay cannot differentiate between serotype-specific and serotype cross-reactive antibodies in patients early after infection, leading to an overestimation of the long-term serotype-specific protection of an antibody response. It is known that the cross-reactive response in patients is temporary but few studies have assessed kinetics and potential changes in serum antibody specificity over time. To better define the specificity of polyclonal antibodies during disease and after recovery, longitudinal samples from patients with primary or secondary DENV-2 infection were collected over a period of 1 year. We found that serotype cross-reactive antibodies peaked 3 weeks after infection and subsided within 1 year. Since secondary patients rapidly produced antibodies specific for the virus envelope (E) protein, an E-specific ELISA was superior compared to a virus particle-specific ELISA to identify patients with secondary infections. Dengue infection triggered a massive activation and mobilization of both naïve and memory B cells possibly from lymphoid organs into the blood, providing an explanation for the surge of circulating plasmablasts and the increase in cross-reactive E protein-specific antibodies.

Vesicular stomatitis virus replicon expressing the VP2 outer capsid protein of bluetongue virus serotype 8 induces complete protection of sheep against challenge infection.

Bluetongue virus (BTV) is an arthropod-borne pathogen that causes an often fatal, hemorrhagic disease in ruminants. Different BTV serotypes occur throughout many temperate and tropical regions of the world. In 2006, BTV serotype 8 (BTV-8) emerged in Central and Northern Europe for the first time. Although this outbreak was eventually controlled using inactivated virus vaccines, the epidemic caused significant economic losses not only from the disease in livestock but also from trade restrictions. To date, BTV vaccines that allow simple serological discrimination of infected and vaccinated animals (DIVA) have not been approved for use in livestock. In this study, we generated recombinant RNA replicon particles based on single-cycle vesicular stomatitis virus (VSV) vectors. Immunization of sheep with infectious VSV replicon particles expressing the outer capsid VP2 protein of BTV-8 resulted in induction of BTV-8 serotype-specific neutralizing antibodies. After challenge with a virulent BTV-8 strain, the vaccinated animals neither developed signs of disease nor showed viremia. In contrast, immunization of sheep with recombinant VP5 - the second outer capsid protein of BTV - did not confer protection. Discrimination of infected from vaccinated animals was readily achieved using an ELISA for detection of antibodies against the VP7 antigen. These data indicate that VSV replicon particles potentially represent a safe and efficacious vaccine platform with which to control future outbreaks by BTV-8 or other serotypes, especially in previously non-endemic regions where discrimination between vaccinated and infected animals is crucial.

The response to vaccination against influenza A(H1N1) 2009, seasonal influenza and Streptococcus pneumoniae in adult outpatients with ongoing treatment for cancer with and without rituximab

It is debated whether cancer patients treated with chemotherapy can mount an adequate response to vaccination.Material and methods. Ninety-six adult outpatients with cancer, who were undergoing chemotherapy and/or monoclonal antibody, tyrosine kinase inhibitor, irradiation or corticosteroid treatments, were studied. Two doses of the pandemic influenza A(H1N1)/09 AS03-adjuvanted split virion vaccine, one dose of the seasonal influenza vaccine and one dose of the 23-valent pneumococcal polysaccharide vaccine were given. Serum haemagglutination inhibition (HI) assays were used to determine antibody titres against the influenza strains. For the pneumococcal vaccine 14 different serotype-specific anti-capsular antibodies were measured by bead assay xMAP®.Results. Patients treated with rituximab did not respond to vaccination. For patients without rituximab treatment 4% had putatively protective antibodies before vaccination (HI ≥ 40) to the pandemic-like strain A/California7/2009HINI. After the first and second dose of vaccine, seroprotection rates (SPR) were 62% and 87%, and seroconversion rates (SCR) 62% and 84%, respectively. Before seasonal flu vaccination SPR against influenza A/Brisbane/59/2007H1N1 and A/Uruguay/10/2007H3N2 were 19% and 17%, respectively. After vaccination, SPR were 70% and 59% and SCR 42% and 50%, respectively. For the pneumococcal vaccine protective antibodies were found to 40% of the 14 strains before and to 68% after vaccination. The mean response to pneumococcal vaccination was to 44% of the 14 serotypes. A response to at least 50% of the 14 serotypes was found in 49% of the patients. No serious adverse events were reported.Conclusion. A substantial number of adult cancer patients with ongoing chemotherapy treatment could mount an adequate serological response to influenza and pneumococcal vaccination without severe adverse events. Thus, vaccination should be recommended. Adjuvanted vaccines may improve the vaccine response among this patient group. Patients recently treated with rituximab do not respond to vaccination.

Increase in hippocampal water diffusion and volume during experimental pneumococcal meningitis is aggravated by bacteremia.

BackgroundThe hippocampus undergoes apoptosis in experimental pneumococcal meningitis leading to neurofunctional deficits in learning and memory function. The aim of the present study was 1) to investigate hippocampal apparent diffusion coefficient (ADC) and volume with MRI during the course of experimental pneumococcal meningitis, 2) to explore the influence of accompanying bacteremia on hippocampal water distribution and volume, 3) and to correlate these findings to the extent of apoptosis in the hippocampus.MethodsExperimental meningitis in rats was induced by intracisternal injection of live pneumococci. The study comprised of four experimental groups. I. Uninfected controls (n = 8); II. Meningitis (n = 11); III. Meningitis with early onset bacteremia by additional i.v. injection of live pneumococci (n = 10); IV. Meningitis with attenuated bacteremia by treatment with serotype-specific anti-pneumococcal antibodies (n = 14). T2 and diffusion weighted MR images were used to analyze changes in hippocampus volume and water diffusion (ADC). The results were correlated to ADC of the cortex, to ventricular volume, and to the extent of hippocampal apoptosis.ResultsBoth ADC and the volume of hippocampus were significantly increased in meningitis rats compared to uninfected controls (Kruskal-Wallis test, p = 0.0001, Dunns Post Test, p < 0.05), and were significantly increased in meningitis rats with an early onset bacteremia as compared to meningitis rats with attenuated bacteremia (p < 0.05). Hippocampal ADC and the volume and size of brain ventricles were positively correlated (Spearman Rank, p < 0.05), whereas no association was found between ADC or volume and the extent of apoptosis (p > 0.05).ConclusionsIn experimental meningitis increase in volume and water diffusion of the hippocampus are significantly associated with accompanying bacteremia.