African swine fever (ASF) is a highly lethal haemorrhagic disease of swine caused by African swine fever virus (ASFV), a unique and genetically complex virus. The disease continues to be a huge ...burden to the pig industry in Africa, Europe and recently in Asia, especially China. The purpose of this review was to recapitulate the current scenarios and evolving trends in ASF vaccine development. The unavailability of an applicable ASF vaccine is partly due to the complex nature of the virus, which encodes various proteins associated with immune evasion. Moreover, the incomplete understanding of immune protection determinants of ASFV hampers the rational vaccine design. Developing an effective ASF vaccine continues to be a challenging task due to many undefined features of ASFV immunobiology. Recent attempts on DNA and live attenuated ASF vaccines have been reported with promising efficacy, and especially live attenuated vaccines have been proved to provide complete homologous protection. Single‐cycle viral vaccines have been developed for various diseases such as Rift Valley fever and bluetongue, and the rational extension of these strategies could be helpful for developing single‐cycle ASF vaccines. Therefore, live attenuated vaccines in short term and single‐cycle vaccines in long term would be the next generation of ASF vaccines.
African swine fever (ASF), caused by African swine fever virus, is a hemorrhagic and often fatal disease of domestic pigs and wild boar, which is notifiable to the World Organization for Animal ...Health. On August 3, 2018, China reported the first outbreak of ASF in Shenyang, a northeastern city of China. As of October 8, a total of 33 ASF outbreaks were reported in eight provinces in China, the biggest pork producer and consumer in the world.
This commentary summarizes the current situation of ASF in China, measures that China has taken to control the disease, lessons learnt from other countries, challenges and recommendations on ASF control in China, and possible international collaborations on ASF.
ASF is an unprecedented disaster and challenge to the Chinese swine industry. It will be a formidable and protracted campaign to control ASF in China, which requires joint participation and coordination of stakeholders and agencies at different levels.
•Pseudorabies (PR) has a high economic impact in China.•We review the epidemiology, diagnosis, control and challenges of PR in China.•PR is endemic in China, though gE-deleted vaccines have been ...widely used.•Recently an emerging PRV variant is prevalent in Bartha-vaccinated swine herds in China.•DIVA strategy-based eradication campaigns are urgently needed to control PR.
Pseudorabies (PR), also known as Aujeszky’s disease (AD), is caused by pseudorabies virus (PRV) or called suid herpesvirus 1 (SuHV-1). It is an economically significant viral disease of pigs and other animals. Although the disease has been eradicated in commercial swine populations of some countries using gE-deleted vaccines and differentiating infected from vaccinated animals (DIVA) strategy, PR continues to be one of the most important diseases of pigs in many countries, particularly in regions with dense pig populations, including China. This article reviews the current situation of PR in China, including epidemiology, diagnostic assays, control strategies and challenges of the disease. PR has been endemic in most provinces of China largely due to the lack of appropriate compulsory vaccination campaigns of pigs, sufficient awareness and biosecurity measures, although gE-deleted vaccines based on the Bartha-K61 strain and regional DIVA-based eradication programs have been widely used in the past decades. Notably, since 2011, an emerging variant PRV with enhanced pathogenicity has become prevalent in vaccinated swine herds in many regions of China and the disease situation is worsening. Control and eventual eradication of PR remain a big challenge in China, and strengthened control measures based on updated DIVA strategy are urgently needed toward national eradication of PR.
African swine fever (ASF), caused by African swine fever virus (ASFV), is a highly contagious disease with high morbidity and mortality in domestic pigs. Although adaptation of ASFV to Vero cells has ...been investigated, the phenotypic changes and the corresponding genomic variations during adaptation of ASFV to other cell lines remain unclear. To obtain a cell‐adapted ASFV strain, different cell lines were tested to determine whether they support ASFV infection. Interestingly, the ASFV wild‐type strain ASFV‐HLJ/18 can infect HEK293T cells and replicate at a low level. After continuous passaging, the adapted ASFV strain can replicate efficiently in both HEK293T and Vero cells. However, the adapted ASFV strain displayed reduced infectivity in primary porcine alveolar macrophages compared to the corresponding wild‐type strain. Furthermore, stepwise losses at the left variable end of the MGF genes and accumulative mutations were identified during passaging, indicating that the ASFV strain gradually adapted to HEK293T cells. Comparison of MGF deletions in other cell culture‐adapted ASFV strains revealed that the deletions of MGF300 (1L, 2R and 4L) and MGF360 genes (8L, 9L, 10L and 11L) play an important role for the adaptation of ASFV to HEK293T cells at the early stage. The biological functions of the deletions and mutants associated with ASFV infection in HEK293T cells and pigs warrant further study. Overall, our findings provide new targets to elucidate the molecular mechanism of adaptation of ASFV to cell lines.
We report acute antibody responses to SARS-CoV-2 in 285 patients with COVID-19. Within 19 days after symptom onset, 100% of patients tested positive for antiviral immunoglobulin-G (IgG). ...Seroconversion for IgG and IgM occurred simultaneously or sequentially. Both IgG and IgM titers plateaued within 6 days after seroconversion. Serological testing may be helpful for the diagnosis of suspected patients with negative RT-PCR results and for the identification of asymptomatic infections.
•This article presents the current knowledge of the strategies and challenges for the development of mucosal vaccines.•Immunization route and vaccine formulation largely determine immunogenicity of ...mucosal vaccines.•Mucosal adjuvants and targeted strategies for improving the effectiveness of mucosal vaccines are explored.•Future directions and research emphasis for new candidate mucosal vaccines are summarized.
Mucosal immunization has potential benefits over conventional parenteral immunization, eliciting immune defense in both mucosal and systemic tissue for protecting from pathogen invasion at mucosal surfaces. To provide a first line of protection at these entry ports, mucosal vaccines have been developed and hold a significant promise for reducing the burden of infectious diseases. However, until very recently, only limited mucosal vaccines are available. This review summarizes recent advances in selected aspects regarding mucosal vaccination, including appropriate administration routes, reasonable formulations, antigen-sampling and immune responses of mucosal immunity, and the strategies used to improve mucosal vaccine efficacy. Finally, the challenges of developing successful mucosal vaccines and the potential solutions are discussed.
•CSF is an OIE-listed, economically important disease of swine worldwide.•We review the epidemiology, diagnostic assays, control and challenges of CSF in China.•CSF is endemic or sporadic and ...compulsory vaccination has been implemented in China.•CSF is basically under control yet far from being eradicated in China.•Eradication of CSF is necessary and possible with DIVA strategy being developed.
Classical swine fever (CSF), caused by Classical swine fever virus (CSFV), is an OIE-listed, highly contagious, often fatal disease of swine worldwide. Currently, the disease is controlled by prophylactic vaccination in China and many other countries using the modified live vaccines derived from C-strain, which was developed in China in the mid-1950s. This minireview summarizes the epidemiology, diagnostic assays, control and challenges of CSF in China. Though CSF is essentially under control, complete eradication of CSF in China remains a challenging task and needs long-term, joint efforts of stakeholders.
•The PRV variant TJ strain was isolated from a vaccinated pig farm in China.•Bartha-K61 strain could not provide complete protection from TJ strain challenge.•TJ strain exhibited higher pathogenicity ...in mice and pigs, compared with SC strain.•The TJ strain genome showed extensive, unique variations in most viral proteins.
Pseudorabies (PR) or Aujeszky's disease (AD), caused by pseudorabies virus (PRV), is an economically important viral disease worldwide. Recently, PR outbreaks occurred in a large number of Bartha-K61-vaccinated swine herds in many regions of China. Here, we isolated a PRV variant, named TJ strain, from a Bartha-K61-vaccinated pig farm in China, evaluated the pathogenicity of the TJ strain in susceptible animals and analyzed its complete genomic sequence obtained by 454 pyrosequencing. Vaccination-challenge experiment in sheep showed that the classical Bartha-K61 vaccine could not provide complete protection against the challenge with the PRV TJ strain. In mice, the 50% lethal dose (LD50) of the TJ strain (102.3 TCID50) was lower than that of the classical PRV SC strain (103.0 TCID50). Furthermore, the TJ strain displayed higher mortality for pigs, as compared with the SC strain. The PRV TJ strain genome was determined to be 143,642bp in length, encoding 67 open reading frames. The TJ strain was clustered to an independent branch together with some recent PRV isolates in China in the phylogenetic tree, which was relatively distant from previous PRV isolates. The TJ strain showed unique variations in the viral proteins that play key roles in the viral replication cycle. Taken together, the TJ strain is a highly pathogenic PRV variant with unique molecular signatures. Further studies are needed to explore the relevance of the sequence differences to the virulence alteration of the PRV variant.
African swine fever virus (ASFV) is a large double-stranded DNA virus with an icosahedral multilayered structure. ASFV causes a lethal swine hemorrhagic disease and is currently responsible for ...widespread damage to the pork industry in Asia. Neither vaccines nor antivirals are available and the molecular characterization of the ASFV particle is outstanding. Here, we describe the cryogenic electron microscopy (cryo-EM) structure of the icosahedral capsid of ASFV at 4.6-Å. The ASFV particle consists of 8,280 copies of the major capsid protein p72, 60 copies of the penton protein, and at least 8,340 minor capsid proteins, of which there might be 3 different types. Like other nucleocytoplasmic large DNA viruses, the minor capsid proteins form a hexagonal network below the outer capsid shell, functioning as stabilizers by “gluing” neighboring capsomers together. Our findings provide a comprehensive molecular model of the ASFV capsid architecture that will contribute to the future development of countermeasures, including vaccines.
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•Cryo-EM structure of the icosahedrally averaged ASFV capsid described at 4.6-Å•ASFV capsid comprises 8,280 major capsid protein p72 and 60 penton protein copies•At least three different minor proteins stabilize capsid by gluing neighboring capsomers•ASFV differs from other NCLDVs in multilayered structure and icosahedral morphology
African swine fever virus (ASFV) is a large DNA virus that causes a lethal swine hemorrhagic disease and is currently responsible for widespread outbreaks in domestic pigs. Liu et al. describe the cryo-EM structure of ASFV capsid at 4.6-Å, which reveals several critical proteins and structural elements.
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