Thoughts on the research of African swine fever live-attenuated vaccines.

African swine fever (ASF) is a contagious and fatal disease caused by the African swine fever virus (ASFV), which can infect pigs of all breeds and ages. Most infected pigs have poor prognosis, leading to substantial economic losses for the global pig industry. Therefore, it is imperative to develop a safe and efficient commercial vaccine against ASF. The development of ASF vaccine can be traced back to 1960. However, because of its large genome, numerous encoded proteins, and complex virus particle structure, currently, no effective commercial vaccine is available. Several strategies have been applied in vaccine design, some of which are potential candidates for vaccine development. This review provides a comprehensive analysis on the safety and effectiveness, suboptimal immunization effects at high doses, absence of standardized evaluation criteria, notable variations among strains of the same genotype, and the substantial impact of animal health on the protective efficacy against viral challenge. All the information will be helpful to the ASF vaccine development.

Chromosome stability of synthetic Triticum turgidum-Aegilops umbellulata hybrids.

BACKGROUND: Unreduced gamete formation during meiosis plays a critical role in natural polyploidization. However, the unreduced gamete formation mechanisms in Triticum turgidum-Aegilops umbellulata triploid F1 hybrid crosses and the chromsome numbers and compostions in T. turgidum-Ae. umbellulata F2 still not known. RESULTS: In this study, 11 T.turgidum-Ae. umbellulata triploid F1 hybrid crosses were produced by distant hybridization. All of the triploid F1 hybrids had 21 chromosomes and two basic pathways of meiotic restitution, namely first-division restitution (FDR) and single-division meiosis (SDM). Only FDR was found in six of the 11 crosses, while both FDR and SDM occurred in the remaining five crosses. The chromosome numbers in the 127 selfed F2 seeds from the triploid F1 hybrid plants of 10 crosses (no F2 seeds for STU 16) varied from 35 to 43, and the proportions of euploid and aneuploid F2 plants were 49.61% and 50.39%, respectively. In the aneuploid F2 plants, the frequency of chromosome loss/gain varied among genomes. The chromosome loss of the U genome was the highest (26.77%) among the three genomes, followed by that of the B (22.83%) and A (11.81%) genomes, and the chromosome gain for the A, B, and U genomes was 3.94%, 3.94%, and 1.57%, respectively. Of the 21 chromosomes, 7U (16.54%), 5 A (3.94%), and 1B (9.45%) had the highest loss frequency among the U, A, and B genomes. In addition to chromosome loss, seven chromosomes, namely 1 A, 3 A, 5 A, 6 A, 1B, 1U, and 6U, were gained in the aneuploids. CONCLUSION: In the aneuploid F2 plants, the frequency of chromosome loss/gain varied among genomes, chromsomes, and crosses. In addition to variations in chromosome numbers, three types of chromosome translocations including 3UL·2AS, 6UL·1AL, and 4US·6AL were identified in the F2 plants. Furthermore, polymorphic fluorescence in situ hybridization karyotypes for all the U chromosomes were also identified in the F2 plants when compared with the Ae. umbellulata parents. These results provide useful information for our understanding the naturally occurred T. turgidum-Ae. umbellulata amphidiploids.

Pien Tze Huang (PZH) protects endothelial function in diabetic mice.

Endothelial dysfunction is the most common pathological feature of cardiovascular diseases, including diabetes mellitus, hypertension and atherosclerosis. It affects both macro- and micro-vasculatures, causing functional impairment of multiple organs. Pien Tze Huang (PZH) is a well-studied traditional Chinese medicine (TCM) with multiple pharmacological properties that produces therapeutic benefits against colorectal cancer, non-alcoholic steatohepatitis and neurodegenerative diseases. However, it is unknown how PZH affects vascular function under pathological conditions. Therefore, this study aimed to investigate the effect of PZH on endothelial function and the underlying mechanisms in db/db diabetic mice. The results showed that chronic treatment of PZH (250 mg/kg/day, 5 weeks) improved endothelial function by restoring endothelium-dependent relaxation through the activation of the Akt-eNOS pathway and inhibition of endothelial oxidative stress, which increased nitric oxide bioavailability. Furthermore, PZH treatment increased insulin sensitivity and suppressed inflammation in diabetic mice. These new findings suggest that PZH may have vaso-protective properties and the potential to protect against diabetic vasculopathy by preserving endothelial function.

Phylogeny and Fungal Community Structures of Helotiales Associated with Sclerotial Disease of Mulberry Fruits in China.

Mulberry fruit sclerotiniose is a prevalent disease caused by the fungal species Ciboria shiraiana, C. carunculoides, and Scleromitrula shiraiana of the order Helotiales, and severely affects the production of mulberry. However, these species have only been identified using morphological and rDNA-ITS sequence analyses, and their genetic variation is unclear. To address this, morphological and two-locus (ITS and RPB2) phylogenetic analyses were conducted using culture-dependent and independent methods for 49 samples from 31 orchards across four provinces in China. Illumina MiSeq sequencing was used to assess the fungal communities obtained from fruits varying in disease severity and color from an orchard in Wuhan. Conidial suspensions of C. shiraiana and C. carunculoides isolated from diseased fruits, diseased fruits affected with hypertrophy and pellet sorosis sclerotiniose, and mycelia of Sclerotinia sclerotiorum were determined to be pathogenic to the mulberry cultivar YSD10. However, fruits inoculated with S. sclerotiorum mycelia exhibited nontypical disease symptoms, and mycelia and conidia obtained from C. carunculoides and S. shiraiana strains were not pathogenic. Maximum parsimony and Bayesian analyses using the sequences of the assessed loci indicated species variability with no evidence of geographic specialization. Metagenomic analysis revealed that the diversity of fungal communities was reduced with disease progression. Furthermore, within a single fruit, the presence of two Ciboria spp. was detected. These results provide novel insights into Ciboria spp., revealing the secondary infections caused by conidia in diseased fruits, genetic variations of the pathogens, and the occurrence of coinfection. This improved understanding of fungal pathogens will aid in developing effective disease control strategies.

The development of robotics courses for young children under vector space model.

Robotics education is important in training children's thinking, practical, and innovation abilities. It is significant to stimulate children's interest in learning and improve their learning quality. The existing research has not paid attention to the application of robotics education in children. It is necessary to stimulate children's interest in learning. This paper will take senior kindergarten students as the research object. It analyzes the application of the Vector Space Model (VSM) in robotics course development. The research and development of children's robotics courses incorporating Artificial Intelligence technology are based on the survey results of robotics courses offered by 38 kindergartens in Baoji City. An automatic document classification system based on VSM is designed to assist in compiling robotics teaching textbooks. Finally, the system performance is tested. The results show that about 24% of kindergartens offer robotics courses, and 76% do not. Besides, 70.14% of teachers support the establishment of children's robotics courses. The classification effect of the VSM system is better than that of Chinese documents. This system performs better than the automatic document classification system based on Term Frequency-Inverse Document Frequency. Its classification accuracy, recall, and F1 value are all above 85%. The development of the robotics course provides a better teaching environment for teaching young children about AI and robots. The robotics education discussed in this paper is a hot spot in the current curriculum reform and is of great significance to the development and innovation in early childhood education.

First Report of Neocosmospora mori Causing Root Rot and Stem Blight of Mulberry in Nanzhang, Hubei, China.

Mulberry (Morus alba L.) has been cultivated for thousands of years in many temperate regions in East Asia and is commonly used to feed silkworms. In May 2021, 5 to 8% incidence of stem blight on 4-year-old mulberry 'Nongsang 14' was observed in several orchards in Nanzhang County, Hubei Province, China. The roots and stems showed symptoms of vascular discoloration, and the tender new shoots, surrounded by white hyphae, were detached easily. Symptomatic stem tissues (5 mm × 5 mm) were excised from the border between diseased and healthy tissues, surface sterilized in a 75% ethanol solution for 30 s and 2.5% sodium hypochlorite for 1.5 min, washed three times in sterile distilled water, then placed on potato dextrose agar (PDA, 250 g potatoes, 2% dextrose, 1.6% agar), and incubated at 25°C in darkness. Two isolates (Bq2 and Bq3) were subcultured using the single-spore method. On PDA, colonies were cottony, with whitish aerial mycelium and the daily growth rate was 4.25 to 5.50 mm/day at 25°C in darkness. On carnation leaf agar, macroconidia were fusiform with slightly curved apical cells and foot-shaped basal cells, three to five septate, measuring 47.5 to 80.3 × 3.6 to 5.6 µm (average 68.7 × 4.7 µm, n = 30). On spezieller nährstoffarmer agar, microconidia were produced in false heads on monophialides, mostly 0-septate, oval, obovoid, or reniform in shape, measuring 5.1 to 10.7 × 2.7 to 5.3 µm (average 8.5 × 3.3 µm, n = 30). Chlamydospores were 4.9 to 11.0 µm in diameter (average 6.8 µm, n = 30), round shaped, thick-walled, and produced individually or in pairs or in chains. For molecular identification, the ribosomal internal transcribed spacers (ITS), translation elongation factor 1α (EF-1α), 28S large subunit nrDNA (LSU), and calmodulin (CAM) genes were amplified and sequenced with primers ITS1/ITS4 (White et al. 1990), EF1H/EF2T (O'Donnell et al. 1998), LR0R/LR5 ( Vilgalys and Hester 1990; Vilgalys and Sun 1994), and CL1/CL2A (Geiser et al. 2021; Wang et al. 2011), respectively. The sequences were deposited in GenBank (OQ711943-OQ711944 for ITS, OQ722438- Q722439 for EF-1α, OQ722441-OQ722442 for CAM, and OR116152-OR116153 for LSU). A maximum-likelihood phylogenetic analysis based on multilocus sequences was conducted using MEGA7, which showed that the two isolates grouped into a clade with Neocosmospora mori (previously Fusarium solani species complex) supported by a high bootstrap value (85%), and hence, they were identified as N. mori based on morphological and molecular analyses (Brooks et al. 2022; Crous et al. 2021; Lombard et al. 2015; Zeng and Zhuang 2023). To complete Koch's postulates, three healthy 2-month-old seedlings grown in sterile peat mix were removed from pots and the roots were washed in sterile water. Each plant was inoculated by dipping wounded and unwounded roots in a spore suspension (1 × 107 conidia/ml) for 20 min, and then 10 mL of the spore suspension was poured over the roots of each seedling after transplanting. Three plants were treated with sterilized water as a control. The tested plants were then kept in a plastic box containing sterile water and incubated at 25°C in a 12 h/12 h light/dark cycle. The pathogenicity assay was repeated three times for each isolate. Root and stem blight was observed 10 days after inoculation, while the control plants were asymptomatic. Furthermore, fungi with morphological characteristics of N. mori were only reisolated from the symptomatic stems and sequences of LSU matched those of isolates Bq2 and Bq3. This pathogen has been reported previously causing stem blight on mulberry trees in Japan and South Korea (Sandoval-Denis et al. 2019), but to our knowledge, this is the first report of N. mori causing root rot and stem blight of mulberry in China. This report will facilitate the development of effective control strategies for the disease.

Disomic 1M (1B) Triticum aestivum-Aegilops comosa Substitution Line with Favorable Protein Properties.

Aegilops comosa (2n = 2x = 14, MM) contains many excellent genes/traits for wheat breeding. Wheat-Ae. comosa introgression lines have potential value in the genetic improvement of wheat quality. A disomic 1M (1B) Triticum aestivum-Ae. comosa substitution line NAL-35 was identified by fluorescence in situ hybridization and genomic in situ hybridization analysis from a hybridization cross between a disomic 1M (1D) substitution line NB 4-8-5-9 with CS N1BT1D. The observation of pollen mother cells showed that NAL-35 had normal chromosome pairing, suggesting that NAL-35 could be used for the quality test. NAL-35 with alien Mx and My subunits showed positive effects on some protein-related parameters including high protein content and high ratios of high-molecular-weight glutenin subunits (HMW-GSs)/glutenin and HMW-GS/low-molecular-weight glutenin subunits. The changes in gluten composition improved the rheological properties of the dough of NAL-35, resulting in a tighter and more uniform microstructure. NAL-35 is a potential material for wheat quality improvement that transferred quality-related genes from Ae. comosa.

Gallotannin Isolated from Pericarp of Water Caltrop Ameliorates High-Fat Diet-Induced Nonalcoholic Fatty Liver Disease in Mice.

Nonalcoholic fatty liver disease (NAFLD) is a worldwide prevalent chronic liver disease characterized by hepatic steatosis. Water caltrop, the fruit of Trapa natan, is widely cultivated as an edible vegetable in Asian countries. In China, water caltrop pericarp has long been used as a functional food to treat metabolic syndrome, yet the bioactive substances and their pharmacological mechanisms remain unclear. In this study, a natural gallotannin, 1,2,3,6-tetra-O-galloyl-ß-D-glucopyranoside (GA), was isolated from water caltrop pericarp and evaluated for its therapeutic effect on NAFLD. Treatment of GA (15 and 30 mg/kg/day) suppressed the body weight gain (p < 0.001) and ameliorated lipid deposition (p < 0.001) in high-fat diet (HFD)-induced NAFLD mice. GA was able to alleviate HFD-induced insulin resistance (p < 0.001), oxidative stress (p < 0.001), and inflammation (p < 0.001), thereby restoring the liver function in HFD-induced NAFLD mice. Mechanistically, GA diminished the aberrant signaling pathways including AMPK/SREBP/ACC, IRs-1/Akt, IKK/IκB/NF-κB in HFD-induced NAFLD mice and modified gut microbiota dysbiosis in these mice as well. The current findings suggest that GA is a promising novel agent for NAFLD therapy.

Attenuated African swine fever virus through serial passaging of viruses in cell culture: a brief review on the knowledge gathered during 60 years of research.

African swine fever virus (ASFV) is a highly pathogenic double-stranded DNA virus. It affects various breeds of pigs, causing serious economic losses and health threats because of its rapid spread and high pathogenicity and infectivity. This situation is not helped by the lack of a validated vaccine or effective therapies. Since the 1960s, different strains of ASFV have been subjected to serial passage in a variety of cell lines. The attenuated ASFV strains obtained through serial passage are not only candidates for ASF vaccine research, but also are useful to study the molecular genetic characteristics and pathogenic mechanism of the virus. This review summarizes related studies on the attenuated strains of ASFV acquired through cell passage over the last 60 years, with the aim of providing inspiration for the rational design of vaccines in future.

Engagement of the G3BP2-TRIM25 Interaction by Nucleocapsid Protein Suppresses the Type I Interferon Response in SARS-CoV-2-Infected Cells.

The nucleocapsid (N) protein contributes to key steps of the SARS-CoV-2 life cycle, including packaging of the virus genome and modulating interactions with cytoplasmic components. Expanding knowledge of the N protein acting on cellular proteins and interfering with innate immunity is critical for studying the host antiviral strategy. In the study on SARS-CoV-2 infecting human bronchial epithelial cell line s1(16HBE), we identified that the N protein can promote the interaction between GTPase-activating protein SH3 domain-binding protein 2 (G3BP2) and tripartite motif containing 25 (TRIM25), which is involved in formation of the TRIM25-G3BP2-N protein interactome. Our findings suggest that the N protein is enrolled in the inhibition of type I interferon production in the process of infection. Meanwhile, upgraded binding of G3BP2 and TRIM25 interferes with the RIG-I-like receptor signaling pathway, which may contribute to SARS-CoV-2 escaping from cellular innate immune surveillance. The N protein plays a critical role in SARS-CoV-2 replication. Our study suggests that the N protein and its interacting cellular components has potential for use in antiviral therapy, and adding N protein into the vaccine as an antigen may be a good strategy to improve the effectiveness and safety of the vaccine. Its interference with innate immunity should be strongly considered as a target for SARS-CoV-2 infection control and vaccine design.

Different T-cell and B-cell repertoire elicited by the SARS-CoV-2 inactivated vaccine and S1 subunit vaccine in rhesus macaques.

Multiple types of SARS-CoV-2 vaccines have been used worldwide, but summarizing their immunologic efficacy post-vaccination remains challenging. The BCR and TCR sequencing based on single-cell sorting makes it possible to evaluate the vaccine-induced immune responses of B or T cells. In this study, we compared the repertoire diversities of B cells and T cells between a whole-virus inactivated vaccine and an S1 protein subunit vaccine in rhesus macaques. We found that the inactivated vaccine could induce a large antigen-specific-BCR repertoire with longer VH CDR3 (21 aa), while the CD3+ TCR α chains of the two vaccine groups showed a similar TCRV/J usage frequency. Detailed analysis of the TCR and BCR repertoires might be of interest for further understanding of the mechanisms of vaccine-induced immune responses.

Nasal Mucosa Exploited by SARS-CoV-2 for Replicating and Shedding during Reinfection.

Reinfection risk is a great concern with regard to the COVID-19 pandemic because a large proportion of the population has recovered from an initial infection, and previous reports found that primary exposure to SARS-CoV-2 protects against reinfection in rhesus macaques without viral presence and pathological injury; however, a high possibility for reinfection at the current stage of the pandemic has been proven. We found the reinfection of SARS-CoV-2 in Syrian hamsters with continuous viral shedding in the upper respiratory tracts and few injuries in the lung, and nasal mucosa was exploited by SARS-CoV-2 for replication and shedding during reinfection; meanwhile, no viral replication or enhanced damage was observed in the lower respiratory tracts. Consistent with the mild phenotype in the reinfection, increases in mRNA levels in cytokines and chemokines in the nasal mucosa but only slight increases in the lung were found. Notably, the high levels of neutralizing antibodies in serum could not prevent reinfection in hamsters but may play roles in benefitting the lung recovery and symptom relief of COVID-19. In summary, Syrian hamsters could be reinfected by SARS-CoV-2 with mild symptoms but with obvious viral shedding and replication, and both convalescent and vaccinated patients should be wary of the transmission and reinfection of SARS-CoV-2.

First Report of Colletotrichum aenigma Causing Anthracnose on Mulberry Leaves in China.

Mulberry (Morus alba L.) has been grown worldwide as a crop for silkworm rearing for over five thousand years (Jiao et al. 2020). In July 2021, a leaf spot disease was observed on mulberry leaves in Wuhan city (114°33'E, 30°48'N), Hubei province, China, with approximately 40% of leaves (about 300 trees) affected. Early symptoms were light brown, with small lesions subsequently expanding to larger sometimes irregular dark brown or black spots surrounded by yellow-brown margins, with easily perforated necrotic lesions. Leaf tissues (5 mm×5 mm) were excised from the border between diseased and healthy tissues, surface sterilized with 75% ethanol solution for 30 s and 2.5% sodium hypochlorite for 2 min, washed thrice in sterile distilled water, and then placed on potato dextrose agar (PDA), and incubated at 25°C in darkness. Four isolates (C1, C9, CHS2, and CHS6) were subcultured using the single-spore method. On PDA, colonies were cottony, pale white from above, and white to grayish-green on the reverse side. Conidia were aseptate, hyaline, subcylindrical with broadly rounded ends, 8.4 to 18.3×4.1 to 7.7 µm (mean = 13.9×5.5 µm, n = 30). Appressoria were typically elliptic or irregular with a few lobes, dark brown, 5.9 to 9.6×4.2 to 8.1 µm (mean = 7.9 ×5.7 µm, n = 30). The morphological characteristics of the isolates matched the descriptions of Colletotrichum gloeosporioides species complex (Weir et al. 2012). The isolates were further identified by analysis of the ribosomal internal transcribed spacers (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), calmodulin (CAL), actin (ACT), chitin synthase (CHS-1), glutamine synthetase (GS), and ß-tubulin 2 (TUB2) genes, amplified respectively with ITS1/ITS4, GDF/GDR, CL1C/CL2C, ACT-512F/ACT-783R, CHS-79F/CHS-345R, GSF1/GSR, and Bt2a/Bt2b (Glass and Donaldson 1995; Weir et al. 2012; White et al. 1990). The sequences were deposited in GenBank (ON492187-ON492214). Concatenated sequences of the seven genes in addition to Colletotrichum species sequences from GenBank were used to conduct a phylogenetic analysis using Maximum-Likelihood (ML) method in MEGA7. The four isolates were grouped into a clade with Colletotrichum aenigma supported by a high bootstrap value (89%), and hence, they were identified as C. aenigma based on the morphological and molecular analyses. To confirm Koch's postulates, wounded leaves of six healthy 2-month-old seedlings made by a sterile needle were inoculated with each isolate by spraying 10 ml of conidial suspensions (105 conidia/ml) on each plant, and the control plants were treated with sterile distilled water. All the treated plants were kept in a plastic box containing sterile water and incubated at 28°C in a 12 h/12 h light/dark cycle. The test was performed three times. After 7 days, typical anthracnose lesions appeared on all inoculated leaves, whereas control plants remained asymptotic. Furthermore, C. aenigma was only reisolated from the symptomatic leaves. Previous studies reported five Colletotrichum species (C. morifolium, C. fioriniae, C. brevisporum, C. karstii, and C. kahawae subsp. ciggaro) to cause this disease on mulberry in China (Tian, 1981; Xue et al. 2019). To our knowledge, this is the first report of C. aenigma causing anthracnose on mulberry in China. The finding will facilitate epidemiological studies and the development of effective control strategies for the disease.

Longitudinal analyses reveal distinct immune response landscapes in lung and intestinal tissues from SARS-CoV-2-infected rhesus macaques.

The pathological and immune response of individuals with COVID-19 display different dynamics in lung and intestine. Here, we depict the single-cell transcriptional atlas of longitudinally collected lung and intestinal tissue samples from SARS-CoV-2-infected monkeys at 3 to 10 dpi. We find that intestinal enterocytes are degraded at 3 days post-infection but recovered rapidly, revealing that infection has mild effects on the intestine. Crucially, we observe suppression of the inflammatory response and tissue damage related to B-cell and Paneth cell accumulation in the intestines, although T cells are activated in the SARS-CoV-2 infection. Compared with that in the lung, the expression of interferon response-related genes is inhibited, and inflammatory factor secretion is reduced in the intestines. Our findings indicate an imbalance of immune dynamic in intestinal mucosa during SARS-CoV-2 infection, which may underlie ongoing rectal viral shedding and mild tissue damage.

Identification and Characterization of Wheat-Aegilops comosa 7M (7A) Disomic Substitution Lines with Stripe Rust and Powdery Mildew Resistance.

Aegilops comosa (MM, 2n = 2x = 14), an important diploid species from the wheat tertiary gene pool, contains many unique genes/traits of potential use for wheat breeding, such as disease resistance. In this study, three sister lines, NAL-32, NAL-33, and NAL-34, were identified from a wheat-A. comosa distant cross using fluorescence in situ hybridization, simple sequence repeat markers, and PCR-based unique gene markers combined with single nucleotide polymorphism (SNP) array analysis. Genetically, NAL-32 contained neither an alien nor translocation chromosome, whereas NAL-33 and NAL-34 had disomic 7M (7A) substitution chromosomes but differed in the absence or presence of the 1BL/1RS translocation chromosomes, respectively. The absence of 7A in NAL-33 and NAL-34 and the unusual 1B in the latter were verified by wheat 55K SNP arrays. The two 7M (7A) substitution lines had similar levels of resistance to stripe rust and powdery mildew, but better than that of NAL-32 and their common wheat parents, suggesting that the stripe rust and powdery mildew resistance of NAL-33 and NAL-34 were derived from the 7M of A. comosa. This research provides important bridge materials that can potentially be used for transferring stripe rust and powdery mildew resistance.

Phenolic profiles, antioxidant activity and inhibition of digestive enzymes of water caltrop pericarps.

BACKGROUND: Water caltrop (Trapa natans L.) is widely cultivated as a popular vegetable or fruit in Asian countries. In China, water caltrop pericarp is also used as a functional food to treat metabolic syndrome. However, the profiling of bioactive substances and their pharmacological activities in different water caltrop varieties remains to be investigated. In the present study, three varieties of water caltrop pericarps collected from 13 origins in China were analyzed for their phenolic substances. To investigate the pharmacological activities, samples were tested for their free radical scavenging capacity and inhibitory potency against α-glucosidase and pancreatic lipase. RESULTS: In total, 46 phenolic compounds were identified in the ethanol extract of water caltrop pericarp using a liquid chromatography-quadrupole time of flight-tandem mass spectrometry method, most of which were hydrolyzable tannins. Two cultivated varieties samples exhibited a relatively higher phenolic content and stronger antioxidant and inhibitory activities against α-glucosidase and pancreatic lipase compared to those from the wild variety. Correlation analysis between phenolic contents and biological activities suggested that phenolic compounds exhibited potential free radical scavenging capacity, α-glucosidase and pancreatic lipase inhibitory activities. CONCLUSION: It is concluded that the phenolic compounds of water caltrop pericarp are promising sources of natural antioxidants, α-glucosidase and pancreatic lipase inhibitors. © 2021 Society of Chemical Industry.

H1N1 exposure during the convalescent stage of SARS-CoV-2 infection results in enhanced lung pathologic damage in hACE2 transgenic mice.

ABSTRACTThe risk of secondary infection with SARS-CoV-2 and influenza A virus is becoming a practical problem that must be addressed as the flu season merges with the COVID-19 pandemic. As SARS-CoV-2 and influenza A virus have been found in patients, understanding the in vivo characteristics of the secondary infection between these two viruses is a high priority. Here, hACE2 transgenic mice were challenged with the H1N1 virus at a nonlethal dose during the convalescent stage on 7 and 14 days post SARS-CoV-2 infection, and importantly, subsequent H1N1 infection showed enhanced viral shedding and virus tissue distribution. Histopathological observation revealed an extensive pathological change in the lungs related to H1N1 infection in mice recovered from SARS-CoV-2 infection, with severe inflammation infiltration and bronchiole disruption. Moreover, upon H1N1 exposure on 7 and 14 dpi of SARS-CoV-2 infection, the lymphocyte population activated at a lower level with T cell suppressed in both PBMC and lung. These findings will be valuable for evaluating antiviral therapeutics and vaccines as well as guiding public health work.

Self-Assembling Nanoparticle Vaccines Displaying the Receptor Binding Domain of SARS-CoV-2 Elicit Robust Protective Immune Responses in Rhesus Monkeys.

SARS-CoV-2 caused the COVID-19 pandemic that lasted for more than a year. Globally, there is an urgent need to use safe and effective vaccines for immunization to achieve comprehensive protection against SARS-CoV-2 infection. Focusing on developing a rapid vaccine platform with significant immunogenicity as well as broad and high protection efficiency, we designed a SARS-CoV-2 spike protein receptor-binding domain (RBD) displayed on self-assembled ferritin nanoparticles. In a 293i cells eukaryotic expression system, this candidate vaccine was prepared and purified. After rhesus monkeys are immunized with 20 µg of RBD-ferritin nanoparticles three times, the vaccine can elicit specific humoral immunity and T cell immune response, and the neutralizing antibodies can cross-neutralize four SARS-CoV-2 strains from different sources. In the challenge protection test, after nasal infection with 2 × 105 CCID50 SARS-CoV-2 virus, compared with unimmunized control animals, virus replication in the vaccine-immunized rhesus monkeys was significantly inhibited, and respiratory pathology observations also showed only slight pathological damage. These analyses will benefit the immunization program of the RBD-ferritin nanoparticle vaccine in the clinical trial design and the platform construction to present a specific antigen domain in the self-assembling nanoparticle in a short time to harvest stable, safe, and effective vaccine candidates for new SARS-CoV-2 isolates.