Impact of mAb-induced A475V substitution on viral fitness and antibody neutralization of SARS-CoV-2 omicron variants in the presence of monoclonal antibodies and human convalescent sera

The emergence and rapid evolution of SARS-CoV-2 variants have posed a major challenge to the global efforts to control the COVID -19 pandemic. In this study, we investigated the potential of two SARS-CoV-2 variants, BA.2 and BA.5, to evade neutralization by a human monoclonal antibody targeting the virus’s spike RBD (mAb 1D1). By subjecting the viruses to serial propagation in the presence of the antibody, we found that BA.2 exhibited poor growth, whereas BA.5 regained robust growth with significantly higher kinetics than the parental virus. Genetic analysis identified a single mutation, A475V, in the spike protein of BA.5 that substantially reduced the neutralizing activities of monoclonal antibodies and convalescent sera. In addition, the A475V mutation alone in BA.2 moderately reduced the neutralizing activity but completely abolished the neutralizing effect of mAb 1D1 when F486V or L452R were also present. Our results shed light on the possible evolutionary development of SARS-CoV-2 variants under selection pressure by monoclonal antibodies and have implications for the development of effective antibody therapies and vaccines against the virus

Treatment of dragonfruit ( Hylocereus polyrhizus ) with salicylic acid and methyl jasmonate improves postharvest physico-chemical properties and antioxidant activity during cold storage

As the market for tropical fruit constantly expands, cold storage is increasingly used for transporting fruits over long distances. This is an economic postharvest tool, yet challenges tropical fruits by exposure to chilling injury. An assessment of the effect of abiotic stresses, induced by cold storage, on dragonfruit was conducted. Dragonfruit was treated with salicylic acid (SA) and methyl jasmonate (MJ) and subjected to cold storage for three weeks. Fruits were treated with either SA or MJ, administered at four different concentrations, along with an untreated control, and stored at 6 °C. Changes in biochemical quality parameters, along with bioactive content and antioxidant activity were assessed during storage. Application of SA was found to reduce the metabolic activity of the fruit, as determined by soluble solids content and titratable acidity. Meanwhile, MJ significantly enhanced the betacyanin content and antioxidant activity. We demonstrate that cold storage can be applied for dragonfruit, by combining the treatment with the application of hormones, especially MJ which can enhance the antioxidant activity of dragonfruit under cold storage

Genomic Polymorphism of the Pandemic A (H1N1) Influenza Viruses Correlates with Viral Replication, Virulence, and Pathogenicity In Vitro and In Vivo

The novel pandemic A (H1N1) virus was first identified in Mexico in April 2009 and quickly spread worldwide. Like all influenzas, the H1N1 strain-specific properties of replication, virulence, and pathogenicity are a result of the particular genomic sequence and concerted expression of multiple genes. Thus, specific mutations may support increased virulence and may be useful as biomarkers of potential threat to human health. We performed comparative genomic analysis of ten strains of the 2009 pandemic A (H1N1) influenza viruses to determine whether genotypes associated with clinical phenotypes, which ranged from mild to severe illness and up to lethal. Virus replication capacity was tested for each strain in vitro using cultured epithelial cells, while virulence and pathogenicity were investigated in vivo using the BALB/c mouse model. The results indicated that A/Sichuan/1/2009 strain had significantly higher replication ability and virulence than the other strains, and five unique non-synonymous mutations were identified in important gene-encoding sequences. These mutations led to amino acid substitutions in HA (L32I), PA (A343T), PB1 (K353R and T566A), and PB2 (T471M), and may be critical molecular determinants for replication, virulence, and pathogenicity. Our results suggested that the replication capacity in vitro and virulence in vivo of the 2009 pandemic A (H1N1) viruses were not associated with the clinical phenotypes. This study offers new insights into the transmission and evolution of the 2009 pandemic A (H1N1) virus

Experimental co-infections of calves with Bluetongue virus serotypes 1 and 8

&lt;p&gt;The contemporary circulation of multiple bluetongue virus (BTV) serotypes or strains within the same territory can imply the co-infection of the ruminant and/or the vector populations. As a consequence, the clinical and pathological outcomes of co-infections as well as the biological properties of the viral progeny could be influenced and exhibit relevant variation. In this study, two independent co-infection experiments were carried out in calves using European strains of BTV serotypes 1 and 8 (BTV-1 and BTV-8, respectively), with the objective of studying the clinical and virological outcomes in comparison with BTV-1 and BTV-8 single infections. Synchronous co-infections using the same titre for the two viral strains were performed and the clinical signs were quantified using a standardized clinical form. Serotype-specific real-time RT-PCRs and viral isolation were used to monitor the course of viraemia. Neutralizing antibody titres were measured during the experiments, and necropsy with viral detection in the affected organs was performed. In the co-infected calves, a high BTV-8 viraemia was detected, while BTV-1 viraemia was irregular and sporadic. During BTV-1 single infection the development of viraemia and high titres of anti-BTV-1 neutralizing antibodies proved that the inoculum was infectious and the detection protocols were efficient. Several hypotheses could explain the predominant detection of BTV-8 in the co-infected calves, such as the occurrence of a privileged BTV-8 segment 2 reassortment, as recently described during in vitro BTV-1/BTV-8 co-infections; interference between the two viral strains; or a higher BTV-8 tropism for the bovine species.&lt;/p&gt;</p

Characterization of influenza A virus pseudotyped with the spikeprotein of porcine epidemic diarrhea virus

AbstractThe coronavirus spike protein and the influenza virus hemagglutinin are class I viral membrane fusion proteins. Whilethe two proteins display strong structural conservation and the mechanisms underlying membrane fusion are similar, theyshare no sequence similarity. Whether they are functionally interchangeable is currently unknown. In this study, we constructedscIAV-S, a single-cycle influenza A virus pseudotyped with the spike protein of porcine epidemic diarrhea virus(PEDV), and demonstrated that this virus could infect cultured cells and trigger massive syncytium formation. Treatmentwith endocytosis inhibitors did not affect syncytium formation by infected cells. Moreover, the infectivity of scIAV-S wasassociated with the degree of cell adaptation of PEDV-S. Intriguingly, scIAV-S lacking functional neuraminidase (NA)exhibited substantially higher infectivity, suggesting a pivotal role of the sialic acid in the binding/entry of PEDV. Together,scIAV-S offers a robust platform for the investigation of the entry mechanism of PEDV or, possibly, of other coronaviruses