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In tropical and subtropical countries, dengue virus (DENV) infections have been increasing; however, we still lack effective therapy. In the present study, we aimed to engineer a bispecific antibody (subsequently named LUZ-8F2–6B1), based on monoclonal antibody 6B1, which has anti DENV-1, 2, and 3 activity, and 8F2, which has anti DENV-4 activity. LUZ-8F2–6B1 displayed potent neutralization activity against four serotypes of DENV by binding to the envelop protein. In vivo , we demonstrated that LUZ-8F2–6B1 could provide protection against infection by four serotypes of DENV in a mouse model. In addition, the deletion of nine amino acids in the Fc region (LUZ-8F2–6B1-9del) completely abolished the antibody-dependent enhancement observed at lower doses of the antibody. Thus, LUZ-8F2–6B1 is a promising, safe, and effective agent for the prophylaxis and treatment of DENV infection. • An engineered bispecific antibody LUZ-8F2-6B1 showed potent neutralization activity against all four serotypes of DENV. • In vivo, a mouse model showed that LUZ-8F2-6B1 provided protection against infection by all four serotypes of DENVs. • LUZ-8F2-6B1-9del completely abrogated antibody dependent enhancement, which occurs when using lower doses of the antibody. • LUZ-8F2-6B1 could be an effective and safe agent for the prophylaxis and therapy of DENV infection. [ABSTRACT FROM AUTHOR]

Human adenovirus serotype 7 (HAdV-7), belonging to species B, has caused severe lower respiratory tract diseases and even deaths recently. However, no adenovirus vaccine or therapeutic is available thus far. In this study, a HAdV-7-specific human monoclonal antibody (HMAb), 3-3E, isolated from single plasma cells obtained from the peripheral blood mononuclear cells of HAdV-7-infected patients showed potent HAdV-7 neutralization activity. The results showed HMAb 3-3E only binds to the hexon protein of intact HAdV-7 or the recombinant hexon protein and it does not bind to other intact virion particles. This could mean the antibody recognizes a conformational epitope of the hexon protein. Further, HMAb 3-3E potently neutralized HAdV-7 in vitro at low concentrations. In vivo studies showed HMAb 3-3E protected from HAdV-7 infection in a murine model. Therefore, HMAb 3-3E is promising as a safe and effective prophylactic and therapeutic treatment for HAdV-7 infection. [ABSTRACT FROM AUTHOR]

Porcine reproductive and respiratory syndrome virus (PRRSV) causes inflammatory injuries in infected pigs. PRRSV induces secretion of high mobility group box 1 (HMGB1) that enhances inflammatory response. However, the mechanism of PRRSV-induced HMGB1 secretion is unknown. Here, we discovered PRRSV induced HMGB1 secretion via activating protein kinase C-delta (PKCδ). HMGB1 secretion was positively correlated with PKCδ activation in PRRSV-infected cells in a dose and time-dependent manner. Suppression of PKCδ with inhibitor and siRNA significantly blocked PRRSV-induced HMGB1 translocation and secretion, which indicates PKCδ activation is essential for the PRRSV-mediated HMGB1 secretion. In addition, PKCδ knockdown in PRRSV-infected cells led to downregulation of inflammatory cytokines, including IL-1beta and IL-6. Moreover, PRRSV E and pORF5a proteins were found to activate PKCδ and consequent HMGB1 secretion. These results demonstrate PRRSV activates PKCδ to induce HMGB1 secretion via E and pORF5a. This finding provides insights on the inflammatory response and pathogenesis of PRRSV infection. [ABSTRACT FROM AUTHOR]

Human adenovirus type 7 (HAdV7) is commonly associated with febrile acute respiratory disease (ARD) outbreaks. We have reported that 10G12, a mouse monoclonal antibody (mAb) specifically recognizing and neutralizing HAdV7, is a promising candidate for humanization. In this study, we engineered the six variants of 10G12 with increased degree of humanization and investigated their biological activity. The humanized monoclonal antibody (mAb) 10G12-M2 was shown to retain the parental antibody's high binding affinity, specificity and potent efficacy of viral suppression. The mAb 10G12-M2 recognized a conformational neutralization epitope of the hexon protein. Complex structure-based molecular docking simulation showed that the hexon protein formed several interactions with 10G12-M2, including hydrogen bonds and salt bridges interaction. Physicochemical properties analysis of 10G12-M2 demonstrated that it is stable and desirable lead candidate. In general, 10G12-M2 had excellent biological activity after humanization combined with the potential for use in prophylactic or therapeutic applications against HAdV7. • The first report of the assess of the humanized mAb that can neutralize HAdV7. • A novel candidate therapeutic antibody with high binding affinity, specificity and potent efficacy of viral suppression. • A novel anti-HAdV7 antibody recognized a conformational neutralization epitope of the hexon protein. • A antibody had excellent physicochemical properties for use in prophylactic or therapeutic applications against HAdV7. [ABSTRACT FROM AUTHOR]

Dengue virus (DENV) is a prevalent mosquito-transmitted human pathogen, causing about 100 million cases of acute dengue fever and 21,000 deaths annually worldwide. Therapeutic neutralizing antibodies against dengue virus might be effective to treat severe dengue fever. Here, we showed that human monoclonal antibody (HMAb) 9C7 bound to all four intact serotypes of DENV but not to the recombinant envelope protein, suggesting HMAb 9C7 recognized a conformational epitope of the envelope protein. Taken together our results suggested that HMAb 9C7 neutralized all four serotypes of DENV in vitro and, for DENV-1, indicated activity at the pre- and post-attachment steps in the viral life cycle. HMAb 9C7 potently protected suckling mice from lethal challenge with all four serotypes of DENV. FcγRII-mediated uptake of immune complexes and antibody-dependent enhancement at low doses of the antibody were abolished by two Leu-to-Ala (9C7-LALA) mutations or deletion of nine amino acids (9C7-9del) in HMAb 9C7 Fc. Therefore, HMAb 9C7 represented a promising prophylactic and therapeutic agent against all four serotypes of DENV. • We generated and characterized a novel DENV-specific HMAb 9C7 recognized a conformational epitope of the envelope protein. • HMAb 9C7 potently neutralized all four serotypes DENV in vitro at the pre- and post-attachment steps in the viral life cycle. • HMAb 9C7 potently protected model mice from lethal challenge with all four serotypes of DENV. • FcγRII-mediated ADE were abolished by two Leu-to-Ala mutations or deletion of nine amino acids in HMAb 9C7 Fc. [ABSTRACT FROM AUTHOR]

Mumps virus (MuV) is postulated to adhere to the “rule of six” for efficient replication. To examine the requirement for MuV, minigenomes of nonpolyhexameric length (6 n −1 and 6 n +1) were analyzed. Expression of the reporter gene CAT was significantly reduced with minigenomes of nonpolyhexameric length compared to the wild type 6 n genome, and reduction was more pronounced for the 6 n −1 than for the 6 n +1 minigenome. That 6 n −1 genomes are impacted by nonconformance with the rule of six to a greater degree as compared to 6 n +1 genomes was also suggested with MuV derived from cDNA coding for 6 n +1 or 6 n −1 genomes. While viruses recovered from 6 n +1 cDNAs maintained a nonpolyhexameric genome length over multiple replication cycles, viruses rescued from the 6 n −1 cDNAs acquired length correcting mutations rapidly following rescue. Our data indicate that polyhexameric genomes are the preferred template for the MuV RNA polymerase, but that this requirement is not absolute. [ABSTRACT FROM AUTHOR]