Zika virus infection during pregnancy can cause congenital abnormities or fetal demise. The persistence of Zika virus in the male reproductive system poses a risk of sexual transmission. Here we demonstrate that live-attenuated Zika virus vaccine candidates containing deletions in the 3' untranslated region of the Zika virus genome (ZIKV-3'UTR-LAV) prevent viral transmission during pregnancy and testis damage in mice, as well as infection of nonhuman primates. After a single-dose vaccination, pregnant mice challenged with Zika virus at embryonic day 6 and evaluated at embryonic day 13 show markedly diminished levels of viral RNA in maternal, placental, and fetal tissues. Vaccinated male mice challenged with Zika virus were protected against testis infection, injury, and oligospermia. A single immunization of rhesus macaques elicited a rapid and robust antibody response, conferring complete protection upon challenge. Furthermore, the ZIKV-3'UTR-LAV vaccine candidates have a desirable safety profile. These results suggest that further development of ZIKV-3'UTR-LAV is warranted for humans.Zika virus infection can result in congenital disorders and cause disease in adults, and there is currently no approved vaccine. Here Shan et al. show that a single dose of a live-attenuated Zika vaccine prevents infection, testis damage and transmission to the fetus during pregnancy in different animal models.

West Nile virus (WNV) is a mosquito-borne flavivirus that is endemic in Africa, the Middle East, Europe and the United States. There is currently no antiviral treatment or human vaccine available to treat or prevent WNV infection. DNA plasmid-based vaccines represent a new approach for controlling infectious diseases. In rodents, DNA vaccines have been shown to induce B cell and cytotoxic T cell responses and protect against a wide range of infections. In this study, we formulated a plasmid DNA vector expressing the ectodomain of the E-protein of WNV into nanoparticles by using linear polyethyleneimine (lPEI) covalently bound to mannose and examined the potential of this vaccine to protect against lethal WNV infection in mice. Mice were immunized twice (prime--boost regime) with the WNV DNA vaccine formulated with lPEI-mannose using different administration routes (intramuscular, intradermal and topical). In parallel a heterologous boost with purified recombinant WNV envelope (E) protein was evaluated. While no significant E-protein specific humoral response was generated after DNA immunization, protein boosting of DNA-primed mice resulted in a marked increase in total neutralizing antibody titer. In addition, E-specific IL-4 T-cell immune responses were detected by ELISPOT after protein boost and CD8(+) specific IFN-γ expression was observed by flow cytometry. Challenge experiments using the heterologous immunization regime revealed protective immunity to homologous and virulent WNV infection.

Signal-regulatory protein alpha (SIRPA) is a well-known inhibitor of phagocytosis when it complexes with CD47 expressed on target cells. Here we show that SIRPA decreased in vitro infection by a number of pathogenic viruses, including New World and Old World arenaviruses, Zika virus, vesicular stomatitis virus and pseudoviruses bearing the Machupo virus, Ebola virus and SARS-CoV-2 glycoproteins, but not HSV-1, MLV or mNoV. Moreover, mice with targeted mutation of the Sirpa gene that renders it non-functional were more susceptible to infection with the New World arenaviruses Junín virus vaccine strain Candid 1 and Tacaribe virus, but not MLV or mNoV. All SIRPA-inhibited viruses have in common the requirement for trafficking to a low pH endosomal compartment. This was clearly demonstrated with SARS-CoV-2 pseudovirus, which was only inhibited by SIRPA in cells in which it required trafficking to the endosome. Similar to its role in phagocytosis inhibition, SIRPA decreased virus internalization but not binding to cell surface receptors. We also found that increasing SIRPA levels via treatment with IL-4 led to even greater anti-viral activity. These data suggest that enhancing SIRPA's activity could be a target for anti-viral therapies.

STAT3 and KRAS regulate cell proliferation, survival, apoptosis, cell migration, and angiogenesis. Aberrant expression of STAT3 and mutant active forms of KRAS have been well-established in the induction and maintenance of multiple cancers. STAT3 and KRAS mutant proteins have been considered anti-cancer targets; however, they are also considered to be clinically "undruggable" intracellular molecules, except for KRAS(G12C). Here we report a first-in-class molecule, a novel, single domain camelid VHH antibody (15 kDa), SBT-100, that binds to both STAT3 and KRAS and can penetrate the tumor cell membrane, and significantly inhibit cancer cell growth. Additionally, SBT-100 inhibits KRAS GTPase activity and downstream phosphorylation of ERK in vitro. In addition, SBT-100 inhibits the growth of multiple human cancers in vitro and in vivo. These results demonstrate the feasibility of targeting hard-to-reach aberrant intracellular transcription factors and signaling proteins simultaneously with one VHH to improve cancer therapies.

A significant number of SARS-CoV-2-infected individuals naturally overcome viral infection, suggesting the existence of a potent endogenous antiviral mechanism. As an innate defense mechanism, microRNA (miRNA) pathways in mammals have evolved to restrict viruses, besides regulating endogenous mRNAs. In this study, we systematically examined the complete repertoire of human miRNAs for potential binding sites on SARS-CoV-2 Wuhan-Hu-1, Beta, Delta, and Omicron. Human miRNA and viral genome interaction were analyzed using RNAhybrid 2.2 with stringent parameters to identify highly bonafide miRNA targets. Using publicly available data, we filtered for miRNAs expressed in lung epithelial cells/tissue and oral keratinocytes, concentrating on the miRNAs that target SARS-CoV-2 S protein mRNAs. Our results show a significant loss of human miRNA and SARS-CoV-2 interactions in Omicron (130 miRNAs) compared to Wuhan-Hu-1 (271 miRNAs), Beta (279 miRNAs), and Delta (275 miRNAs). In particular, hsa-miR-3150b-3p and hsa-miR-4784 show binding affinity for S protein of Wuhan strain but not Beta, Delta, and Omicron. Loss of miRNA binding sites on N protein was also observed for Omicron. Through Ingenuity Pathway Analysis (IPA), we examined the experimentally validated and highly predicted functional role of these miRNAs. We found that hsa-miR-3150b-3p and hsa-miR-4784 have several experimentally validated or highly predicted target genes in the Toll-like receptor, IL-17, Th1, Th2, interferon, and coronavirus pathogenesis pathways. Focusing on the coronavirus pathogenesis pathway, we found that hsa-miR-3150b-3p and hsa-miR-4784 are highly predicted to target MAPK13. Exploring miRNAs to manipulate viral genome/gene expression can provide a promising strategy with successful outcomes by targeting specific VOCs.

Severe COVID-19 and post-acute sequelae of SARS-CoV-2 infection are associated with neurological complications that may be linked to direct infection of the central nervous system (CNS), but the selective pressures ruling neuroinvasion are poorly defined. Here, we assessed SARS-CoV-2 evolution in the lung versus CNS of infected mice. Higher levels of viral diversity were observed in the CNS than the lung after intranasal challenge with a high frequency of mutations in the Spike furin cleavage site (FCS). Deletion of the FCS significantly attenuated virulence after intranasal challenge, with lower viral titers and decreased morbidity compared to the wild-type virus. Intracranial inoculation of the FCS-deleted virus, however, was sufficient to restore virulence. After intracranial inoculation, both viruses established infection in the lung, but this required reversion of the FCS deletion. Cumulatively, these data suggest a critical role for the FCS in determining SARS-CoV-2 tropism and compartmentalization with possible implications for the treatment of neuroinvasive COVID-19.