The rapid spread of coronavirus SARS-CoV-2 greatly threatens global public health but no prophylactic vaccine is available. Here, we report the generation of a replication-incompetent recombinant ...serotype 5 adenovirus, Ad5-S-nb2, carrying a codon-optimized gene encoding Spike protein (S). In mice and rhesus macaques, intramuscular injection with Ad5-S-nb2 elicits systemic S-specific antibody and cell-mediated immune (CMI) responses. Intranasal inoculation elicits both systemic and pulmonary antibody responses but weaker CMI response. At 30 days after a single vaccination with Ad5-S-nb2 either intramuscularly or intranasally, macaques are protected against SARS-CoV-2 challenge. A subsequent challenge reveals that macaques vaccinated with a 10-fold lower vaccine dosage (1 × 10
viral particles) are also protected, demonstrating the effectiveness of Ad5-S-nb2 and the possibility of offering more vaccine dosages within a shorter timeframe. Thus, Ad5-S-nb2 is a promising candidate vaccine and warrants further clinical evaluation.
Abstract
SARS-CoV-2 vaccination has been launched worldwide to build effective population-level immunity to curb the spread of this virus. The effectiveness and duration of protective immunity is a ...critical factor for public health. Here, we report the kinetics of the SARS-CoV-2 specific immune response in 204 individuals up to 1-year after recovery from COVID-19. RBD-IgG and full-length spike-IgG concentrations and serum neutralizing capacity decreases during the first 6-months, but is maintained stably up to 1-year after hospital discharge. Even individuals who had generated high IgG levels during early convalescent stages had IgG levels that had decreased to a similar level one year later. Notably, the RBD-IgG level positively correlates with serum neutralizing capacity, suggesting the representative role of RBD-IgG in predicting serum protection. Moreover, viral-specific cellular immune protection, including spike and nucleoprotein specific, persisted between 6 months and 12 months. Altogether, our study supports the persistence of viral-specific protective immunity over 1 year.
Vaccines are urgently needed to control the ongoing pandemic COVID-19 and previously emerging MERS/SARS caused by coronavirus (CoV) infections. The CoV spike receptor-binding domain (RBD) is an ...attractive vaccine target but is undermined by limited immunogenicity. We describe a dimeric form of MERS-CoV RBD that overcomes this limitation. The RBD-dimer significantly increased neutralizing antibody (NAb) titers compared to conventional monomeric form and protected mice against MERS-CoV infection. Crystal structure showed RBD-dimer fully exposed dual receptor-binding motifs, the major target for NAbs. Structure-guided design further yielded a stable version of RBD-dimer as a tandem repeat single-chain (RBD-sc-dimer) which retained the vaccine potency. We generalized this strategy to design vaccines against COVID-19 and SARS, achieving 10- to 100-fold enhancement of NAb titers. RBD-sc-dimers in pilot scale production yielded high yields, supporting their scalability for further clinical development. The framework of immunogen design can be universally applied to other beta-CoV vaccines to counter emerging threats.
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•A dimeric form of MERS-CoV RBD is highly immunogenic and protective in mice•RBD-dimer structure guides further design of a homogeneous dimer by tandem repeat•The strategy is generalizable to design beta-CoV vaccines against COVID-19 and SARS•CoV RBD-dimer immunogens can be produced at high yields in pilot scale production
Gao et al. present the structure-guided design of a coronavirus immunogen comprised of two protein subunits each containing the virus spike receptor binding domain fused together via a disulfide link or tandem repeat. The immunogen elicits strong immunogenicity in mice and protects them against viral challenge. The vaccine design strategy can be universally applied to SARS, MERS, COVID-19, and other CoV vaccines to counter emerging threats.
We prospectively assessed 49 coronavirus disease cases in Guangdong, China, to estimate the frequency and duration of detectable severe acute respiratory syndrome coronavirus 2 RNA in human body ...fluids. The prolonged persistence of virus RNA in various body fluids may guide the clinical diagnosis and prevention of onward virus transmission.
Herein, we report that a recombinant fusion protein, containing a 457 amino acid SARS-CoV-2 receptor binding domain (RBD, residues 319-541) and a mouse IgG1 Fc domain, could induce highly potent ...neutralizing antibodies and stimulate humoral and cellular immunity in mice. The antibodies also effectively suppressed SARS-CoV-2 RBD binding to soluble ACE2, indicating that RBD-mFc may be further developed as a safe and effective SARS-CoV-2 vaccine.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel coronavirus first identified in December 2019. Notable features that make SARS-CoV-2 distinct from most other previously ...identified betacoronaviruses include a receptor binding domain and a unique insertion of 12 nucleotides or 4 amino acids (PRRA) at the S1/S2 boundary. In this study, we identified two deletion variants of SARS-CoV-2 that either directly affect the polybasic cleavage site itself (NSPRRAR) or a flanking sequence (QTQTN). These deletions were verified by multiple sequencing methods.
results showed that the deletion of NSPRRAR likely does not affect virus replication in Vero and Vero-E6 cells; however, the deletion of QTQTN may restrict late-phase viral replication. The deletion of QTQTN was detected in 3 of 68 clinical samples and 12 of 24
-isolated viruses, while the deletion of NSPRRAR was identified in 3
-isolated viruses. Our data indicate that (i) there may be distinct selection pressures on SARS-CoV-2 replication or infection
and
; (ii) an efficient mechanism for deleting this region from the viral genome may exist, given that the deletion variant is commonly detected after two rounds of cell passage; and (iii) the PRRA insertion, which is unique to SARS-CoV-2, is not fixed during virus replication
These findings provide information to aid further investigation of SARS-CoV-2 infection mechanisms and a better understanding of the NSPRRAR deletion variant observed here.
The spike protein determines the infectivity and host range of coronaviruses. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has two unique features in its spike protein, the receptor binding domain and an insertion of 12 nucleotides at the S1/S2 boundary resulting in a furin-like cleavage site. Here, we identified two deletion variants of SARS-CoV-2 that either directly affect the furin-like cleavage site itself (NSPRRAR) or a flanking sequence (QTQTN), and we investigated these deletions in cell isolates and clinical samples. The absence of the polybasic cleavage site in SARS-CoV-2 did not affect virus replication in Vero or Vero-E6 cells. Our data indicate the PRRAR sequence and the flanking QTQTN sequence are not fixed
thus, there appears to be distinct selection pressures on SARS-CoV-2 sequences
and
Further investigation of the mechanism of generating these deletion variants and their infectivity in different animal models would improve our understanding of the origin and evolution of this virus.
Coronavirus disease 2019 (COVID-19) is caused by SARS-CoV-2 infection and was first reported in central China in December 2019. Extensive molecular surveillance in Guangdong, China’s most populous ...province, during early 2020 resulted in 1,388 reported RNA-positive cases from 1.6 million tests. In order to understand the molecular epidemiology and genetic diversity of SARS-CoV-2 in China, we generated 53 genomes from infected individuals in Guangdong using a combination of metagenomic sequencing and tiling amplicon approaches. Combined epidemiological and phylogenetic analyses indicate multiple independent introductions to Guangdong, although phylogenetic clustering is uncertain because of low virus genetic variation early in the pandemic. Our results illustrate how the timing, size, and duration of putative local transmission chains were constrained by national travel restrictions and by the province’s large-scale intensive surveillance and intervention measures. Despite these successes, COVID-19 surveillance in Guangdong is still required, because the number of cases imported from other countries has increased.
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•1.6 million tests identified 1,388 SARS-CoV-2 infections in Guangdong by 19 March•Virus genomes can be recovered using a variety of sequencing approaches•Analyses reveal multiple viral importations with limited local transmission•Effective control measures helped reduce and eliminate chains of viral transmission
Genomic and epidemiological analyses provide insights into how COVID-19 was contained in China’s most populous province using a combination of surveillance and travel restriction measures.
In the past decade, the most prevalent norovirus genotype causing viral gastroenteritis outbreaks worldwide, including China, has been GII.4. In winter 2014-15, norovirus outbreaks in Guangdong, ...China, increased. Sequence analysis indicated that 82% of the outbreaks were caused by a norovirus GII.17 variant.
The rapid transmission and potential link to severe neurologica complications and birth defects have made Zika virus infection a serious threat to global public health. However, the initial ancestor ...of Zika virus and the potential transmission route remain are unknown.
We assessed the epidemiological characteristics of 28 confirmed cases of Zika virus infection and analysed the genetic diversity of Zika virus isolates.
28 confirmed cases of Zika virus infection were imported from South America, Central America and south Pacific areas. 18 cases were overseas Chinese people who had emigrated from Jiangmen, Guangdong. The remaining cases were businessman travelling in Venezuela, Samoa, Suriname, Guatemala, and Ecuador. The results of a molecular-clock phylogenetic analysis showed that the evolutionary rate of the Asian lineage was 1·05 × 10−3 substitutions per site per year. The estimated time-scaled phylogeny contains a well-supported cluster of Zika virus strains (posterior probability PP=1·0) that share a common ancestor with the French Polynesia lineage in 2013, which suggests that a common ancestor likely transmitted from French Polynesia to South America, particularly to Brazil. All cases of Zika virus imported into China were located in two independent clusters (PP=1·0). One cluster contained the isolates imported into China from Venezuela. The common ancestor of this clade descended from an ancestral lineage that can be dated to the beginning of 2015; therefore, the imported China isolates from Venezuela were probably already locally endemic before 2015. In another cluster, all the isolates were imported into China from the South Pacific island Samoa. The common ancestor of this cluster can be dated to the middle of 2014. The estimated time-scaled phylogeny indicates that this cluster also shared a common ancestor with French Polynesia strain in 2013 (PP=0·99).
The present data indicated that the imported Zika virus in China was unlikely to be transmitted from Brazil in 2015. Alternatively, an independent local transmission of Zika virus appears to have been previously established in Venezuela and Samoa after 2014 and 2013, respectively.
Guangdong Provincial Science and Technology Program (2015A020213004), Guangdong Provincial Science and Technology (2016A020251001), and National Key R&D Program (2016YFC1200201).
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been redetected after discharge in some coronavirus disease 2019 (COVID-19) patients. The reason for the recurrent positivity of the ...test and the potential public health concern due to this occurrence are still unknown. Here, we analyzed the viral data and clinical manifestations of 289 domestic Chinese COVID-19 patients and found that 21 individuals (7.3%) were readmitted for hospitalization after detection of SARS-CoV-2 after discharge. First, we experimentally confirmed that the virus was involved in the initial infection and was not a secondary infection. In positive retests, the virus was usually found in anal samples (15 of 21, 71.4%). Through analysis of the intracellular viral subgenomic messenger RNA (sgmRNA), we verified that positive retest patients had active viral replication in their gastrointestinal tracts (3 of 16 patients, 18.7%) but not in their respiratory tracts. Then, we found that viral persistence was not associated with high viral titers, delayed viral clearance, old age, or more severe clinical symptoms during the first hospitalization. In contrast, viral rebound was associated with significantly lower levels of and slower generation of viral receptor-binding domain (RBD)-specific IgA and IgG antibodies. Our study demonstrated that the positive retest patients failed to create a robust protective humoral immune response, which might result in SARS-CoV-2 persistence in the gastrointestinal tract and possibly in active viral shedding. Further exploration of the mechanism underlying the rebound in SARS-CoV-2 in this population will be crucial for preventing virus spread and developing effective vaccines.
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