Isolation and Characterization of Mouse Monoclonal Antibodies That Neutralize SARS-CoV-2 and Its Variants of Concern Alpha, Beta, Gamma and Delta by Binding Conformational Epitopes of Glycosylated RBD With High Potency.

Antibodies targeting Receptor Binding Domain (RBD) of SARS-CoV-2 have been suggested to account for the majority of neutralizing activity in COVID-19 convalescent sera and several neutralizing antibodies (nAbs) have been isolated, characterized and proposed as emergency therapeutics in the form of monoclonal antibodies (mAbs). However, SARS-CoV-2 variants are rapidly spreading worldwide from the sites of initial identification. The variants of concern (VOC) B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma) and B.1.167.2 (Delta) showed mutations in the SARS-CoV-2 spike protein potentially able to cause escape from nAb responses with a consequent reduction of efficacy of vaccines and mAbs-based therapy. We produced the recombinant RBD (rRBD) of SARS-CoV-2 spike glycoprotein from the Wuhan-Hu 1 reference sequence in a mammalian system, for mice immunization to isolate new mAbs with neutralizing activity. Here we describe four mAbs that were able to bind the rRBD in Enzyme-Linked Immunosorbent Assay and the transmembrane full-length spike protein expressed in HEK293T cells by flow cytometry assay. Moreover, the mAbs recognized the RBD in supernatants of SARS-CoV-2 infected VERO E6 cells by Western Blot under non-reducing condition or in supernatants of cells infected with lentivirus pseudotyped for spike protein, by immunoprecipitation assay. Three out of four mAbs lost their binding efficiency to completely N-deglycosylated rRBD and none was able to bind the same recombinant protein expressed in Escherichia coli, suggesting that the epitopes recognized by three mAbs are generated by the conformational structure of the glycosylated native protein. Of particular relevance, three mAbs were able to inhibit Wuhan SARS-CoV-2 infection of VERO E6 cells in a plaque-reduction neutralization test and the Wuhan SARS-CoV-2 as well as the Alpha, Beta, Gamma and Delta VOC in a pseudoviruses-based neutralization test. These mAbs represent important additional tools for diagnosis and therapy of COVID-19 and may contribute to the understanding of the functional structure of SARS-CoV-2 RBD.

Electrogenic and hydrocarbonoclastic biofilm at the oil-water interface as microbial responses to oil spill.

The oil-water interface formed during an oil spill represents a challenging environment for pelagic communities living in aquatic ecosystems. At this anoxic barrier, we report the formation of a microbial hydrocarbonoclastic biofilm capable of electron transfer along the water column. This biofilm generated a membrane of surface-active compounds that allowed the spontaneous separation of electrical charges, causing the establishment of an anodic and a cathodic region and, as a result, the spontaneous creation of a liquid microbial fuel cell. Such floating biofilm was connected to the water column underneath by floating filaments that could contribute to oxygen reduction at distance. The filaments revealed an unusual lipid content induced by anoxic conditions, with prominent ultrastructural features similar to myelin found in oligodendrocytes of the vertebrate nervous system. Furthermore, these filaments showed an interesting cross-reactivity towards different epitopes of the myelin basic protein (MBP) and Claudin 11 (O4) of human oligodendrocytes. The presence of a network of filaments similar to myelin suggests the probable existence of evolutionary connections between very distant organisms. Collectively these results suggest a possible mechanism for how lake microbial communities can adapt to oil spills while offering an interesting starting point for technological developments of liquid microbial fuel cells related to the study of hydrocarbon-water interfaces. The data that support the findings of this study are openly available in figshare at https://figshare.com/s/72bc73ae14011dc7920d.

Mumps clinical diagnostic uncertainty.

Background: During recent years, various mumps outbreaks have occurred among populations vaccinated for mumps worldwide. In Italy, improving routine coverage with two doses of measles, mumps and rubella (MMR) vaccine is one of the key strategies to eliminate measles and rubella. To monitor the effect of the vaccination programme on the population, the surveillance of these vaccine-preventable diseases has been implemented. This provided the opportunity to evaluate the accuracy of the clinical diagnosis of those diseases, including mumps. In fact, vaccinated children may develop a variety of diseases caused by a series of different viruses [Epstein-Barr virus (EBV), parainfluenza virus types 1-3, adenoviruses, herpes virus and parvovirus B19] whose symptoms (i.e. swelling of parotid glands) may mimic mumps. For this reason, laboratory diagnosis is essential to confirm clinical suspicion. Methods: The accuracy of clinical diagnosis of mumps was evaluated by differential diagnosis on EBV in Italy, a country at low incidence of mumps. This retrospective study investigated whether the etiology of 131 suspected mumps cases with a negative molecular/serological result for mumps virus, obtained from 2007 to 2016, were due to EBV, in order to establish a diagnosis. Results: Differential diagnosis revealed a EBV positivity rate of 19.8% and all cases were caused by EBV type 1. Conclusions: This study confirms the importance of a lab based differential diagnosis that can discriminate between different infectious diseases presenting with symptoms suggestive of mumps and, in particular, emphasize the importance to discriminate between mumps and EBV-related mononucleosis.