Explore the vast range of titles available.

A single, low-dose intradermal immunization with lipid-nanoparticle-encapsulated nucleoside-modified mRNA encoding the pre-membrane and envelope glycoproteins of Zika virus protects both mice and rhesus macaques against infection and elicits rapid and long-lasting neutralizing antibody responses. mRNA vaccine beats Zika virus Public health efforts to combat Zika virus disease are hampered by lack of a safe and efficient vaccine. Drew Weissman and colleagues report the development of a candidate vaccine that is based on chemically stabilized messenger RNA (mRNA) that encodes the premembrane and envelope glycoproteins of the Zika virus. This mRNA is packaged into lipid nanoparticles that can be delivered intradermally. A single dose of the vaccine gave mice and rhesus macaques long-term immunity to the Zika virus. These findings pave the way for the development of candidate vaccines that could protect humans against Zika virus disease. Zika virus (ZIKV) has recently emerged as a pandemic associated with severe neuropathology in newborns and adults 1 . There are no ZIKV-specific treatments or preventatives. Therefore, the development of a safe and effective vaccine is a high priority. Messenger RNA (mRNA) has emerged as a versatile and highly effective platform to deliver vaccine antigens and therapeutic proteins 2 , 3 . Here we demonstrate that a single low-dose intradermal immunization with lipid-nanoparticle-encapsulated nucleoside-modified mRNA (mRNA–LNP) encoding the pre-membrane and envelope glycoproteins of a strain from the ZIKV outbreak in 2013 elicited potent and durable neutralizing antibody responses in mice and non-human primates. Immunization with 30  μ g of nucleoside-modified ZIKV mRNA–LNP protected mice against ZIKV challenges at 2 weeks or 5 months after vaccination, and a single dose of 50  μ g was sufficient to protect non-human primates against a challenge at 5 weeks after vaccination. These data demonstrate that nucleoside-modified mRNA–LNP elicits rapid and durable protective immunity and therefore represents a new and promising vaccine candidate for the global fight against ZIKV.

Zika virus (ZIKV) was identified as a cause of congenital disease during the explosive outbreak in the Americas and Caribbean that began in 2015. Because of the ongoing fetal risk from endemic disease and travel-related exposures, a vaccine to prevent viremia in women of childbearing age and their partners is imperative. We found that vaccination with DNA expressing the premembrane and envelope proteins of ZIKV was immunogenic in mice and nonhuman primates, and protection against viremia after ZIKV challenge correlated with serum neutralizing activity. These data not only indicate that DNA vaccination could be a successful approach to protect against ZIKV infection, but also suggest a protective threshold of vaccineinduced neutralizing activity that prevents viremia after acute infection.

Flaviviruses sample an ensemble of virion conformations resulting from the conformational flexibility of their structural proteins. To investigate how sequence variation among strains impacts virus breathing, we performed studies with the monoclonal antibody (MAb) E111, which binds an inaccessible domain III envelope (E) protein epitope of dengue virus serotype 1 (DENV1). Prior studies indicated that an observed ~200-fold difference in neutralization between the DENV1 strains Western Pacific-74 (West Pac-74) and 16007 could not be explained by differences in the affinity of MAb E111 for each strain. Through neutralization studies with wild-type and variant viruses carrying genes encoding reciprocal mutations at all 13 amino acid differences between the E proteins of West Pac-74 and 16007, we found that E111 neutralization susceptibility mapped solely to the presence of a lysine or arginine at E domain II residue 204, located distally from the E111 epitope. This same residue correlated with neutralization differences observed for MAbs specific for epitopes distinct from E111, suggesting that this amino acid dictates changes in the conformational ensembles sampled by the virus. Furthermore, an observed twofold difference in the stability of infectious West Pac-74 versus 16007 in solution also mapped to E residue 204. Our results demonstrate that neutralization susceptibility can be altered in an epitope-independent manner by natural strain variation that influences the structures sampled by DENV. That different conformational ensembles of flaviviruses may affect the landscape available for antibody binding, as well as virus stability, has important implications for functional studies of antibody potency, a critical aspect of vaccine development. IMPORTANCE The global burden of dengue virus (DENV) is growing, with recent estimates of ~390 million human infections each year. Antibodies play a crucial role in protection from DENV infection, and vaccines that elicit a robust antibody response are being actively pursued. We report here the identification of a single amino acid residue in the envelope protein of DENV serotype 1 that results in global changes to virus structure and stability when it is changed. Our results indicate that naturally occurring variation at this particular site among virus strains impacts the ensemble of structures sampled by the virus, a process referred to as virus breathing. The finding that such limited and conservative sequence changes can modulate the landscape available for antibody binding has important implications for both vaccine development and the study of DENV-reactive antibodies. The global burden of dengue virus (DENV) is growing, with recent estimates of ~390 million human infections each year. Antibodies play a crucial role in protection from DENV infection, and vaccines that elicit a robust antibody response are being actively pursued. We report here the identification of a single amino acid residue in the envelope protein of DENV serotype 1 that results in global changes to virus structure and stability when it is changed. Our results indicate that naturally occurring variation at this particular site among virus strains impacts the ensemble of structures sampled by the virus, a process referred to as virus breathing. The finding that such limited and conservative sequence changes can modulate the landscape available for antibody binding has important implications for both vaccine development and the study of DENV-reactive antibodies.

Zika virus (ZIKV) is a flavivirus that has emerged as a global health threat due in part to its association with congenital abnormalities. Other globally relevant flaviviruses include dengue virus (DENV) and West Nile virus (WNV). High-resolution structures of ZIKV reveal many similarities to DENV and suggest some differences, including an extended glycan loop (D. Sirohi, Z. Chen, L. Sun, T. Klose, T. C. Pierson, et al., 352:467–470, 2016, http://dx.doi.org/10.1126/science.aaf5316) and unique interactions among envelope (E) protein residues that were proposed to confer increased virion stability and contribute mechanistically to the distinctive pathobiology of ZIKV (V. A. Kostyuchenko, E. X. Lim, S. Zhang, G. Fibriansah, T. S. Ng, et al., Nature 533:425–428, 2016, http://dx.doi.org/10.1038/nature17994). However, in the latter study, virus stability was inferred by measuring the loss of infectivity following a short incubation period. Here, we rigorously assessed the relative stability of ZIKV, DENV, and WNV by measuring changes in infectivity following prolonged incubation at physiological temperatures. At 37°C, the half-life of ZIKV was approximately twice as long as the half-life of DENV (11.8 and 5.2 h, respectively) but shorter than that of WNV (17.7 h). Incubation at 40°C accelerated the loss of ZIKV infectivity. Increasing virion maturation efficiency modestly increased ZIKV stability, as observed previously with WNV and DENV. Finally, mutations at E residues predicted to confer increased stability to ZIKV did not affect virion half-life. Our results demonstrate that ZIKV is not uniquely stable relative to other flaviviruses, suggesting that its unique pathobiology is explained by an alternative mechanism. IMPORTANCE Zika virus (ZIKV) belongs to the Flavivirus genus, which includes other clinically relevant mosquito-borne pathogens such as dengue virus (DENV) and West Nile virus (WNV). Historically, ZIKV infection was characterized by a self-limiting, mild disease, but recent outbreaks have been associated with severe clinical complications, including Guillain-Barré syndrome and microcephaly, which are atypical of other flavivirus infections. Moreover, ZIKV has been detected in saliva, urine, and semen, and it may be sexually transmitted. Analysis of a high-resolution cryo-electron microscopic reconstruction of ZIKV hypothesized that the unusual stability of this virus contributes to its distinctive pathobiology. Here, we directly compared the stability of ZIKV to that of other flaviviruses following prolonged incubation in solution at physiological temperatures. We found that the stability of multiple ZIKV strains, including those from recent outbreaks, is intermediate between that of DENV and WNV, suggesting an alternative explanation for the unique clinical manifestations of ZIKV infection. Zika virus (ZIKV) belongs to the Flavivirus genus, which includes other clinically relevant mosquito-borne pathogens such as dengue virus (DENV) and West Nile virus (WNV). Historically, ZIKV infection was characterized by a self-limiting, mild disease, but recent outbreaks have been associated with severe clinical complications, including Guillain-Barré syndrome and microcephaly, which are atypical of other flavivirus infections. Moreover, ZIKV has been detected in saliva, urine, and semen, and it may be sexually transmitted. Analysis of a high-resolution cryo-electron microscopic reconstruction of ZIKV hypothesized that the unusual stability of this virus contributes to its distinctive pathobiology. Here, we directly compared the stability of ZIKV to that of other flaviviruses following prolonged incubation in solution at physiological temperatures. We found that the stability of multiple ZIKV strains, including those from recent outbreaks, is intermediate between that of DENV and WNV, suggesting an alternative explanation for the unique clinical manifestations of ZIKV infection.

Filamins are long, flexible, multi-domain proteins composed of an N-terminal actin-binding domain (ABD) followed by multiple immunoglobulin-like repeats (IgFLN). They function to organize and maintain the actin cytoskeleton, to provide scaffolds for signaling components, and to act as mechanical force sensors. In this study, we used transcript sequencing and homology modeling to characterize the gene and protein structures of the C. elegans filamin orthologs fln-1 and fln-2. Our results reveal that C. elegans FLN-1 is well conserved at the sequence level to vertebrate filamins, particularly in the ABD and several key IgFLN repeats. Both FLN-1 and the more divergent FLN-2 colocalize with actin in vivo. FLN-2 is poorly conserved, with at least 23 IgFLN repeats interrupted by large regions that appear to be nematode-specific. Our results indicate that many of the key features of vertebrate filamins are preserved in C. elegans FLN-1 and FLN-2, and suggest the nematode may be a very useful model system for further study of filamin function.

The Zika virus epidemic and associated congenital infections have prompted rapid vaccine development. We assessed two new DNA vaccines expressing premembrane and envelope Zika virus structural proteins. We did two phase 1, randomised, open-label trials involving healthy adult volunteers. The VRC 319 trial, done in three centres, assessed plasmid VRC5288 (Zika virus and Japanese encephalitis virus chimera), and the VRC 320, done in one centre, assessed plasmid VRC5283 (wild-type Zika virus). Eligible participants were aged 18–35 years in VRC19 and 18–50 years in VRC 320. Participants were randomly assigned 1:1 by a computer-generated randomisation schedule prepared by the study statistician. All participants received intramuscular injection of 4 mg vaccine. In VRC 319 participants were assigned to receive vaccinations via needle and syringe at 0 and 8 weeks, 0 and 12 weeks, 0, 4, and 8 weeks, or 0, 4, and 20 weeks. In VRC 320 participants were assigned to receive vaccinations at 0, 4, and 8 weeks via single-dose needle and syringe injection in one deltoid or split-dose needle and syringe or needle-free injection with the Stratis device (Pharmajet, Golden, CO, USA) in each deltoid. Both trials followed up volunteers for 24 months for the primary endpoint of safety, assessed as local and systemic reactogenicity in the 7 days after each vaccination and all adverse events in the 28 days after each vaccination. The secondary endpoint in both trials was immunogenicity 4 weeks after last vaccination. These trials are registered with ClinicalTrials.gov, numbers NCT02840487 and NCT02996461. VRC 319 enrolled 80 participants (20 in each group), and VRC 320 enrolled 45 participants (15 in each group). One participant in VRC 319 and two in VRC 320 withdrew after one dose of vaccine, but were included in the safety analyses. Both vaccines were safe and well tolerated. All local and systemic symptoms were mild to moderate. In both studies, pain and tenderness at the injection site was the most frequent local symptoms (37 [46%] of 80 participants in VRC 319 and 36 [80%] of 45 in VRC 320) and malaise and headache were the most frequent systemic symptoms (22 [27%] and 18 [22%], respectively, in VRC 319 and 17 [38%] and 15 [33%], respectively, in VRC 320). For VRC5283, 14 of 14 (100%) participants who received split-dose vaccinations by needle-free injection had detectable positive antibody responses, and the geometric mean titre of 304 was the highest across all groups in both trials. VRC5283 was well tolerated and has advanced to phase 2 efficacy testing. Intramural Research Program of the Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health.