The respiratory syncytial virus fusion protein-specific B cell receptor repertoire reshaped by post-fusion subunit vaccination

Respiratory syncytial virus (RSV) is the major cause of acute lower respiratory illness in children of less than 5 years of age which usually results in hospitalization or even in death. Vaccine development is hampered in consequence of a failed vaccine trial with fatalities in the 1960s. Even though research has been more focused on the RSV fusion protein in its pre-fusion conformation, maternal vaccination with post-fusion protein (post F) was considered as a promising vaccine strategy for passive immunization of babies, because post F preserves very potent neutralizing epitopes. We extensively analyzed post F-binding B cell receptor (BCR) repertoires of three vaccinees who received a post F-subunit vaccine in the context of a first-in-human, Phase 1, randomized, observer-blind, placebo-controlled clinical trial (ClinicalTrials.gov Identifier: NCT02298179). In order to compare the vaccine-induced BCR repertoires with BCR repertoires induced by natural infection, we also analyzed pre F- and post F-binding BCRs isolated from a healthy blood donor with relatively high F-binding memory B cell (MBC) frequencies. Analysis of the vaccine-induced repertoires revealed that preferentially V_H4-encoded BCRs were expanded in response to vaccination. Estimation of antigen-driven selection further demonstrated that expanded BCRs accumulated positively selected replacement mutations which substantiated the hypothesis that post F-vaccination induces diversification of V_H4-encoded BCRs in germinal centers. Comparison of the vaccine-induced BCR repertoires with clonally related pre and post F-binding BCRs of the healthy blood donor suggested that the vaccine expanded pre/post F cross-reactive MBCs. Interestingly, several vaccine-induced BCRs shared stereotypic VDJ gene junctions with known neutralizing Abs. Once expressed for functional characterization, the selected monoclonal Abs demonstrated the predicted neutralization activities in plaque reduction neutralization assays indicating that the post F-vaccine induced expansion of neutralizing BCRs.     

Application of recombinase polymerase amplification method for rapid detection of infectious laryngotracheitis virus

Infectious laryngotracheitis is a significant respiratory disease of chickens that causes huge economic losses due to high morbidity and mortality and reduced egg production. A real-time recombinase polymerase amplification (RPA) assay was developed to accurately detect ILTV. The specific probe and primer sets were carefully designed and screened. The real-time RPA assay was carried out at 39 °C for 30 min, and results were obtained within 15 min. The results of the specificity assay showed no fluorescence signals with other avian-related viruses. The sensitivity of the assay was 1 × 10² copies/μL. The low CV value showed that the assay was reproducible. A total of 115 clinical samples were tested using the real-time RPA assay and the real-time PCR assay in parallel; the coincidence rates of the two detection methods were 100%. The results indicated that the real-time RPA assay is a specific, sensitive, rapid, and useful tool for epidemiological studies and clinical diagnosis, especially in the field and in resource-poor areas.     

PCR仪与测序仪应用于丙型肝炎病毒基因型检测的临床效果观察

目的:观察PCR仪与测序仪在丙型肝炎病毒(HCV)基因型检测中的应用。方法:选择2018年1月~2018年12月收治的134例HCV感染患者为研究对象,给予患者PCR仪检测、测序仪检测。结果:测序仪检测134例均可分型,PCR仪检测130例患者可分型,4例未能分型。PCR检测结果:134例HCV感染患者中,1b型59例,2a型47例,3a型6例,3b型15例,6a型3例,4例为分出型别。基因测序结果:134例均可分型:1型59例,2a型40例,2i型7例,3a型6例,3b型15例,6a型3例,6n型4例。PCR仪检测法检测符合率97.0%。结论:PCR仪测序仪检测用于丙型肝炎病毒基因型检测,操作便捷,但其只能检测探针覆盖的型别,个别罕见型别不能分型。     

Hepatitis B surface antigen seroprevalence among pre- and post-vaccine cohorts in Cambodia, 2017

Background: Hepatitis B virus (HBV) infection is highly endemic in most low income countries including Cambodia. This nationwide serosurvey was conducted to assess the impact of hepatitis B vaccination and to determine whether Cambodia met the WHO regional 2017 target of hepatitis B surface antigen (HBsAg) seroprevalence less than 1% in five-year-old children.Methods: A cross-sectional multi-stage cluster survey was conducted among children born during 2010–2012 and their mothers in Cambodia. HBsAg prevalence was estimated by rapid point-of-care testing, and demographic data, including vaccination history, was collected. Vaccine coverage in children and the prevalence of HBsAg among children and mothers was calculated taking into account the complex survey design. Factors associated with children’s failure to receive timely (within 24 h) vaccination were analysed by multivariate logistic analysis.Findings: A total of 2,520 children 5–7 years old and 2,028 mothers were recruited. In total, 78.4% of children received hepatitis B vaccination birth-dose (HepB-BD); of these, 58.7% were administered ≤ 24 h. Birth at home or “other” location were independent risk factors for children’s failure to receive timely HepB-BD. Overall HBsAg seroprevalence was 4.39% (95%CI: 3.53%–5.45%) among mothers and 0.56% (95%CI: 0.32%–0.98%) among children. The prevalence among children without hepatitis B vaccination was 4.62% (95%CI: 1.31%–14.97%). Among children with a HBsAg-positive mother, prevalence was 10.11% (95%CI: 5.41%–18.11%).Interpretation: Having achieved the 2017 target of less than 1% HBsAg prevalence among 5 years old children, Cambodia can now focus on eliminating mother-to-child transmission of HBV. Moreover, the high HBsAg prevalence among mothers suggests that routine screening with proper linkage to care and treatment is needed. Strengthening measures to improve vaccination coverage further and eliminate mother-to-child transmission by coordinated programming with other services offering additional HBV interventions will help move towards the global goal of hepatitis B elimination by 2030.Funding: As per sources of funding.     

Clinical profile of ankylosing spondylitis patients in Togo

Aim of the workTo determine the clinical characteristics of ankylosing spondylitis (AS) in rheumatology wards in Togo. Patients and methods: The medical records of AS patients in four rheumatology wards in Togo were recorded from January 2000 to December 2019. Results: The study included 37 AS cases out of 35,304 rheumatic diseases patients’ files that were investigated over the preceding 20 years; accounting for 0.1% of hospital cases. Male predominance was noticed with a M:F ratio of 4.3. The mean age at disease onset was 29.6 ± 10.3 years and the mean duration of the symptoms was 9.5 ± 9.2 years. The clinical findings were dominated by spinal pain (91.9%). The main peripheral joints involvements were knees (48.6%) and ankles (35.1%) and the most frequent extra-articular features were ocular with conjunctivitis (13.5%) and uveitis (8.1%) respectively. Plain radiographs of the spine revealed syndesmophytes (45.9%) with bony ankylosis and bamboo spine (21.6%); and that of the pelvis showed sacroiliitis in 89.2%. The human leucocytic antigen (HLA B27) was positive in four cases. Non-steroidal anti-inflammatory drugs (NSAIDs) and sulfasalazine were the most commonly used drugs, respectively in 89.2% and 67.6% of patients. One patient was receiving biologic therapy. Conclusion: Ankylosing spondylitis is relatively rare in Togo. There is no particularity in the clinical features or imaging and laboratory findings. The diagnostic delay reflects the importance of the plain radiograph structural changes. NSAIDs and disease modifying anti-rheumatic drugs (DMARDs) are the cornerstone of the treatment due to their accessibility in Togo.     

Adaptation of Vero cells to suspension growth for rabies virus production in different serum free media

Vero cells are nowadays widely used in the production of human vaccines. They are considered as one of the most productive and flexible continuous cell lines available for vaccine manufacturing. However, these cells are anchorage dependent, which greatly complicates upstream processing and process scale-up. Moreover, there is a recognized need to reduce the costs of vaccine manufacturing to develop vaccines that are affordable worldwide. The use of cell lines adapted to suspension growth contributes to reach this objective.The current work describes the adaptation of Vero cells to suspension culture in different serum free media according to multiple protocols based on subsequent passages. The best one that relies on cell adaption to IPT-AFM an in-house developed animal component free medium was then chosen for further studies. Besides, as aggregates have been observed, the improvement of IPT-AFM composition and mechanical dissociation were also investigated.In addition to IPT-AFM, three chemically defined media (CD293, Hycell CHO and CD-U5) and two serum free media (293SFMII and SFM4CHO) were tested to set up a serum free culture of the suspension-adapted Vero cells (VeroS) in shake flasks. Cell density levels higher than 2 × 10⁶ cells/mL were obtained in the assessed conditions. The results were comparable to those obtained in spinner culture of adherent Vero cells grown on Cytodex 1 microcarriers.Cell infection with LP-2061 rabies virus strain at an MOI (Multiplicity of Infection) of 0.1 and a cell density of 8 ± 0.5 × 10⁵ cells/mL resulted in a virus titer higher than 10⁷ FFU/mL in all media tested. Nevertheless, the highest titer equal to 5.2 ± 0.5 × 10⁷ FFU/mL, was achieved in IPT-AFM containing a reduced amount of Ca⁺⁺ and Mg⁺⁺. Our results demonstrate the suitability of the obtained VeroS cells to produce rabies virus at a high titer, and pave the way to develop VeroS cells bioreactor process for rabies vaccine production.     

Inter‐serotype reassortment among epizootic haemorrhagic disease viruses in the United States

First described in 1955 in New Jersey, epizootic haemorrhagic disease (EHD) causes a severe clinical disease in wild and domestic ruminants worldwide. Epizootic haemorrhagic disease outbreaks occur in deer populations each year from summer to late autumn. The etiological agent is EHD virus (EHDV) which is a double‐stranded segmented icosahedral RNA virus. EHD virus utilizes point mutations and reassortment strategies to maintain viral fitness during infection. In 2018, EHDV serotype 2 was predominantly detected in deer in Illinois. Whole genome sequencing was conducted for two 2018 EHDV2 isolates (IL41747 and IL42218) and the sequence analyses indicated that IL42218 was a reassortant between different serotypes whereas IL41747 was a genetically stable strain. Our data suggest that multiple strains contribute to outbreaks each year.     

Review of clinical characteristics,immune responses and regulatory mechanisms of hepatitis E-associated liver failure

Hepatitis E virus (HEV) is the most common cause of acute liver failure (LF) and one of the most common factors causing acute injury in acute-on-chronic LF (ACLF). When HEV-related LF occurs, a series of changes take place in both the intrahepatic environment and extrahepatic microenvironment. The changed types and distribution of immune cells (infiltrating macrophages and increased lymphocytes) in liver tissue, as well the increased proinflammatory cytokines and chemokines in the blood, indicate that the occurrence and progression of HEV-related LF are closely related to immune imbalance. The clinical features and immune reaction in the body during HEV-related acute LF (ALF) and ACLF are complicated. This review highlights recent progress in elucidating the clinical manifestations of HEV-associated ALF and ACLF and discusses the corresponding systemic immune changes and possible regulatory mechanisms.