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Porcine epidemic diarrhea virus (PEDV) is an enteric coronavirus that causes acute watery diarrhea and vomiting in unweaned piglets, and is associated with high mortality, thus causing severe economic losses in the pig industry. Currently, although attenuated vaccines are commonly used in commercial pig farms in China, they do not completely protect against all mutated wild-type strains. Existing nucleic acid assays have high sensitivity and specificity, but the complexity of the assay process and expensive instrumentation hinder disease detection. Here, reverse transcription–enzymatic recombinase amplification (RT-ERA) was combined with the CRISPR-Cas12a system to develop a rapid diagnostic method to distinguish PEDV wild-type strains from attenuated vaccine strains. The protocol used crRNA and RT-ERA amplification primers against open reading frame 3 (ORF3), followed by Cas12a/crRNA complex detection of predefined target sequences at 37 °C for 30 min, thus producing results visible to the naked eye under LED blue light. The assay is highly sensitive and specific, detecting as few as two copies of the target gene per test and showing no cross-reactivity with other porcine pathogens. Overall, this integrated RT-ERA pre-amplification and Cas12a/crRNA cleavage assay is a practical tool for reliable and rapid detection of PEDV for diagnostic differentiation.

Rift Valley fever virus (RVFV) is a pathogenic arthropod-borne virus that can cause serious illness in both ruminants and humans. The virus can be transmitted by an arthropod bite or contact with contaminated fluids or tissues. Two live-attenuated veterinary vaccines—the Smithburn (SB) and Clone 13 (Cl.13)—are currently used during epizootic events in Africa. However, their residual pathogenicity (i.e., SB) or potential of reversion (i.e., Cl.13) causes important adverse effects, strongly limiting their use in the field. In this study, we infected immunocompetent mice with SB or Cl.13 by a subcutaneous or an intranasal inoculation. Interestingly, we found that, unlike the subcutaneous infection, the intranasal inoculation led to a high mortality rate. In addition, we detected high titers and viral N antigen levels in the brain of both the SB- and Cl.13-infected mice. Overall, we unveil a clear correlation between the pathogenicity and the route of administration of both SB and Cl.13, with the intranasal inoculation leading to a stronger neurovirulence and higher mortality rate than the subcutaneous infection.

•We developed a live vaccine strain YX10p90 by passaging through chicken embryos.•YX10p90 could provide better protection against the QX-like IBV in China.•Amino acid substitutions and a deletion in the 3’-UTR may involve in attenuation. In this study, we attenuated a Chinese QX-like nephropathogenic infectious bronchitis virus (IBV) strain, YX10, by passaging through fertilized chicken eggs. The 90th passage strain (YX10p90) was selected as the live-attenuated vaccine candidate strain. YX10p90 was found to be safe in 7-day-old specific pathogen free chickens without induction of morbidity or mortality. YX10p90 provided nearly complete protection against QX-like (CH I genotype) strains and partial protection against other two major Chinese genotype strains. YX10p90 also showed no reversion to virulence after five back passages in chickens. An IBV polyvalent vaccine containing YX10p90 was developed and showed that it could provide better protection against major Chinese IBV virulent strains than commercial polyvalent vaccines. In addition, the complete genome sequence of YX10p90 was sequenced. Multiple-sequence alignments identified 38 nucleotide substitutions in the whole genome which resulted in 26 amino acid substitutions and a 110-bp deletion in the 3′ untranslated region. In conclusion, the attenuated YX10p90 strain exhibited a fine balance between attenuation and immunogenicity, and should be considered as a candidate vaccine to prevent infection of Chinese QX-like nephropathogenic IBV.

Rabies is a lethal zoonotic disease caused by lyssaviruses, such as rabies virus (RABV), that results in nearly 100% mortality once clinical symptoms appear. There are no curable drugs available yet. RABV contains five structural proteins that play an important role in viral replication, transcription, infection, and immune escape mechanisms. In the past decade, progress has been made in research on the pathogenicity of RABV, which plays an important role in the creation of new recombinant RABV vaccines by reverse genetic manipulation. Here, we review the latest advances on the interaction between RABV proteins in the infected host and the applied development of rabies vaccines by using a fully operational RABV reverse genetics system. This article provides a background for more in-depth research on the pathogenic mechanism of RABV and the development of therapeutic drugs and new biologics.

Porcine epidemic diarrhea virus (PEDV) is an enteric coronavirus that causes acute watery diarrhea and vomiting in unweaned piglets. Infections result in high mortality and serious economic losses to the swine industry. PEDV attenuated vaccine does not completely protect against all mutant wild-type strains, and PEDV infection can periodically occur. A sensitive, accurate, and simple detection method for PEDV is needed to reduce the occurrence of the disease. In this study, the CRISPR/Cas13a system was combined with recombinase aided amplification to develop a rapid diagnostic method to distinguish PEDV wild-type strains from attenuated vaccine strains. The method is based on isothermal detection at 37°C. The results are used for visual readout. The assay had high sensitivity and specificity, with a detection limit of 10 1 copies/μL for the gene of interest, and no cross-reactivity with other pathogens. The Cas13a detection worked well with clinical samples. This visual, sensitive, and specific nucleic acid detection method based on CRISPR/Cas13a should be a powerful tool for detecting PEDV.

Orf (ORF) is an acute disease caused by the Orf virus (ORFV), and poses a certain threat to animal and human health. Live attenuated vaccines play an important role in the prevention and control of ORF. The effectiveness of the live attenuated Orf virus vaccine is influenced by several factors, including the genomic match between the vaccine strain and circulating epidemic strains. Genomic differences between an ORFV epidemic strain (ORFV-2W) and a vaccine strain (ORFV-1V) were identified in this study via analysis of multiple sequence alignments, phylogenetic trees, and single nucleotide polymorphisms. Phylogenetic analysis revealed that ORFV-2W and ORFV-1V were closely related, with a whole genome homology of 99.8%. Furthermore, a deletion in the non-coding region at the end of the whole genome of ORFV-1V was detected. Such non-essential genes in the terminal regions are usually unnecessary for virus replication but may play important roles in pathogenicity, host and tissue tropism. Single nucleotide polymorphism analysis identified three missense mutations in ORF067, ORF072, and the terminal non-coding region of ORFV-1V. Moreover, a frameshift mutation in ORF102 of ORFV-1V was detected. Mutations in individual genes and deletion of terminal non-coding regions may be related to the attenuation of the vaccine strain. These results provide useful context for improving ORFV vaccines.

The Japanese encephalitis (JE) zoonotic vaccine strain ML-17 was sequenced and compared to related JE virus strains to identify genomic attenuation markers. Relative to its parental strain, JaOH0566, 25 nucleotide alterations and 10 amino acid changes to, prM/M(2), NS2A(1), NS4B(3) and NS5(4) proteins were recorded. Both structural-gene changes were in the prM/M region (127Met → Ile and 274Asn → Thr). To study the effects of these prM/M changes, mutants bearing the changes were prepared using an infectious clone of JaOArS982 previously established at this lab. Compared with JaOArS982, mutant 127(Met → Ile) showed marked reduction in murine neuroinvasiveness. Mutant 274(Asn → Thr), showed slight reduction. Neither mutant recorded ML-17-equivalent attenuation, implying that prM/M changes need to combine with other recorded genomic differences to cause attenuation. Importantly, ML-17 with its unchanged E region, presents a possible backbone candidate for preparation of “E-replacement” type live attenuated flavivirus chimeric vaccines.

The global decline in malaria has stalled 1 , emphasizing the need for vaccines that induce durable sterilizing immunity. Here we optimized regimens for chemoprophylaxis vaccination (CVac), for which aseptic, purified, cryopreserved, infectious Plasmodium falciparum sporozoites (PfSPZ) were inoculated under prophylactic cover with pyrimethamine (PYR) (Sanaria PfSPZ-CVac(PYR)) or chloroquine (CQ) (PfSPZ-CVac(CQ))—which kill liver-stage and blood-stage parasites, respectively—and we assessed vaccine efficacy against homologous (that is, the same strain as the vaccine) and heterologous (a different strain) controlled human malaria infection (CHMI) three months after immunization ( https://clinicaltrials.gov/ , NCT02511054 and NCT03083847). We report that a fourfold increase in the dose of PfSPZ-CVac(PYR) from 5.12 × 10 4 to 2 × 10 5 PfSPZs transformed a minimal vaccine efficacy (low dose, two out of nine (22.2%) participants protected against homologous CHMI), to a high-level vaccine efficacy with seven out of eight (87.5%) individuals protected against homologous and seven out of nine (77.8%) protected against heterologous CHMI. Increased protection was associated with Vδ2 γδ T cell and antibody responses. At the higher dose, PfSPZ-CVac(CQ) protected six out of six (100%) participants against heterologous CHMI three months after immunization. All homologous (four out of four) and heterologous (eight out of eight) infectivity control participants showed parasitaemia. PfSPZ-CVac(CQ) and PfSPZ-CVac(PYR) induced a durable, sterile vaccine efficacy against a heterologous South American strain of P. falciparum , which has a genome and predicted CD8 T cell immunome that differs more strongly from the African vaccine strain than other analysed African P. falciparum strains. Two malaria vaccines comprising Plasmodium falciparum sporozoites and treatment with either pyrimethamine or chloroquine induced durable protective responses against both the African vaccine strain and a heterologous South American strain of P. falciparum .

JVC-001 is a new live attenuated measles–mumps–rubella vaccine (measles AIK-C, mumps RIT4385, and rubella Takahashi strains). Two phase 3 studies were conducted, one to verify the non-inferior immunogenicity of JVC-001 versus the approved mumps and measles–rubella vaccines (J301 study) and another to compare the immunogenicity and safety of different titers (J302 study). Both studies were multicenter, randomized, observer-blinded, phase 3 studies. J301 compared the immunogenicity elicited with a single dose of JVC-001 or control vaccines (measles–rubella vaccine + mumps vaccine [Hoshino strain]). J302 was a titer-confirmation study of a single dose of a low- or high-titer formulation of JVC-001. Both studies enrolled healthy Japanese children (aged 1 year) and had a primary efficacy endpoint of seropositive rate on Day 43. Overall, 861 participants completed J301 (JVC-001, n = 429; control, n = 432) and 100 participants completed J302 (low-titer, n = 48; high-titer, n = 52). For measles and rubella virus antibody titer, non-inferiority of JVC-001 was demonstrated: seropositive rates were ≥ 99.5 %. For mumps virus genotype D antibody titer, seropositive rates were 80.6 % (95 % confidence interval 76.5 % to 84.4 %) with JVC-001 and 88.1 % (84.6 % to 91.0 %) with control vaccination. Thus, non-inferiority for mumps virus genotype D antibody titer was not confirmed. Seropositive rates were similar in the low- and high-titer groups. There were no events leading to discontinuation, or cases of aseptic meningitis in either study. Although the non-inferiority of JVC-001 to currently approved vaccines was not demonstrated for the mumps component, clinical significance and consistent efficacy were indicated. Vaccine titer did not affect immunogenicity. JVC-001 is expected to have a lower risk of aseptic meningitis to currently approved vaccines and raised no new safety signals emerged. •JVC-001 is a new MMR vaccine (measles: AIK-C, mumps: RIT4385, rubella: Takahashi).•Comparative clinical trial of JVC-001 was conducted using MR and mumps vaccines.•Non-inferiority of immunogenicity was not demonstrated only against mumps virus.•However, clinical significance and consistent efficacy were indicated for JVC-001.•Different virus doses of JVC-001 did not affect immunogenicity and safety profile.

Influenza viruses cause substantial annual morbidity and mortality globally. Current vaccines protect against influenza only when well matched to the circulating strains. However, antigenic drift can cause considerable mismatches between vaccine and circulating strains, substantially reducing vaccine effectiveness. Moreover, current seasonal vaccines are ineffective against pandemic influenza, and production of a vaccine matched to a newly emerging virus strain takes months. Therefore, there is an unmet medical need for a broadly protective influenza virus vaccine. We aimed to test the ability of chimeric H1 haemagglutinin-based universal influenza virus vaccine candidates to induce broadly cross-reactive antibodies targeting the stalk domain of group 1 haemagglutinin-expressing influenza viruses. We did a randomised, observer-blinded, phase 1 study in healthy adults in two centres in the USA. Participants were randomly assigned to one of three prime–boost, chimeric haemagglutinin-based vaccine regimens or one of two placebo groups. The vaccine regimens included a chimeric H8/1, intranasal, live-attenuated vaccine on day 1 followed by a non-adjuvanted, chimeric H5/1, intramuscular, inactivated vaccine on day 85; the same regimen but with the inactivated vaccine being adjuvanted with AS03; and an AS03-adjuvanted, chimeric H8/1, intramuscular, inactivated vaccine followed by an AS03-adjuvanted, chimeric H5/1, intramuscular, inactivated vaccine. In this planned interim analysis, the primary endpoints of reactogenicity and safety were assessed by blinded study group. We also assessed anti-H1 haemagglutinin stalk, anti-H2, anti-H9, and anti-H18 IgG antibody titres and plasmablast and memory B-cell responses in peripheral blood. This trial is registered with ClinicalTrials.gov, number NCT03300050. Between Oct 10, 2017, and Nov 27, 2017, 65 participants were enrolled and randomly assigned. The adjuvanted inactivated vaccine, but not the live-attenuated vaccine, induced a substantial serum IgG antibody response after the prime immunisation, with a seven times increase in anti-H1 stalk antibody titres on day 29. After boost immunisation, all vaccine regimens induced detectable anti-H1 stalk antibody (2·2–5·6 times induction over baseline), cross-reactive serum IgG antibody, and peripheral blood plasmablast responses. An unsolicited adverse event was reported for 29 (48%) of 61 participants. Solicited local adverse events were reported in 12 (48%) of 25 participants following prime vaccination with intramuscular study product or placebo, in 12 (33%) of 36 after prime immunisation with intranasal study product or placebo, and in 18 (32%) of 56 following booster doses of study product or placebo. Solicited systemic adverse events were reported in 14 (56%) of 25 after prime immunisation with intramuscular study product or placebo, in 22 (61%) of 36 after immunisation with intranasal study product or placebo, and in 21 (38%) of 56 after booster doses of study product or placebo. Disaggregated safety data were not available at the time of this interim analysis. The tested chimeric haemagglutinin-based, universal influenza virus vaccine regimens elicited cross-reactive serum IgG antibodies that targeted the conserved haemagglutinin stalk domain. This is the first proof-of-principle study to show that high anti-stalk titres can be induced by a rationally designed vaccine in humans and opens up avenues for further development of universal influenza virus vaccines. On the basis of the blinded study group, the vaccine regimens were tolerable and no safety concerns were observed. Bill & Melinda Gates Foundation.