Virology-the path forward.

In the United States (US), biosafety and biosecurity oversight of research on viruses is being reappraised. Safety in virology research is paramount and oversight frameworks should be reviewed periodically. Changes should be made with care, however, to avoid impeding science that is essential for rapidly reducing and responding to pandemic threats as well as addressing more common challenges caused by infectious diseases.

The Picornaviridae Family: Knowledge Gaps, Animal Models, Countermeasures, and Prototype Pathogens.

Picornaviruses are nonenveloped particles with a single-stranded RNA genome of positive polarity. This virus family includes poliovirus, hepatitis A virus, rhinoviruses, and Coxsackieviruses. Picornaviruses are common human pathogens, and infection can result in a spectrum of serious illnesses, including acute flaccid myelitis, severe respiratory complications, and hand-foot-mouth disease.

Cross-Reactive Antibody Responses against Nonpoliovirus Enteroviruses.

Enteroviruses are among the most common human viral pathogens. Infection with members of a subgroup of viruses within this genus, the nonpoliovirus enteroviruses (NPEVs), can result in a broad spectrum of serious illnesses, including acute flaccid myelitis (AFM), a polio-like childhood paralysis; neonatal sepsis; aseptic meningitis; myocarditis; and hand-foot-mouth disease. Despite the diverse primary sites of virus infection, including the respiratory and alimentary tracts, and an array of diseases associated with these infections, there is significant genetic and antigenic similarity among NPEVs.

Neurotropism of Enterovirus D68 Isolates Is Independent of Sialic Acid and Is Not a Recently Acquired Phenotype.

Acute flaccid myelitis (AFM) is a rare but serious illness of the nervous system, specifically affecting the gray matter of the spinal cord, motor-controlling regions of the brain, and cranial nerves. Most cases of AFM are pathogen associated, typically with poliovirus and enterovirus infections, and occur in children under the age of 6 years. Enterovirus D68 (EV-D68) was first isolated from children with pneumonia in 1962, but an association with AFM was not observed until the 2014 outbreak.

Cell-type specificity and functional redundancy of RIG-I-like receptors in innate immune sensing of Coxsackievirus B3 and encephalomyocarditis virus.

The contributions of RIG-I and MDA5 receptors to sensing viruses of the Picornaviridae family were investigated. The picornaviruses encephalomyocarditis virus (EMCV) and Coxsackievirus B3 (CVB3) are detected by both MDA5 and RIG-I in bone marrow derived macrophages. In macrophages from wild type mice, type I IFN is produced early after infection; IFNβ synthesis is reduced in the absence of each sensor, while IFNα production is reduced in the absence of MDA5.

Replication of early and recent Zika virus isolates throughout mouse brain development.

Fetal infection with Zika virus (ZIKV) can lead to congenital Zika virus syndrome (cZVS), which includes cortical malformations and microcephaly. The aspects of cortical development that are affected during virus infection are unknown. Using organotypic brain slice cultures generated from embryonic mice of various ages, sites of ZIKV replication including the neocortical proliferative zone and radial columns, as well as the developing midbrain, were identified.

Polioviruses that bind a chimeric Pvr-nectin-2 protein identify capsid residues involved in receptor interaction.

Amino acid changes in the C'C"D region in poliovirus receptor domain 1 disrupt poliovirus binding. To examine further the role of the C'C"D region in poliovirus infection, we substituted this region of Pvr into the corresponding region of a murine homolog, nectin-2. The chimeric receptor, nectin-2, rendered transformed L cells susceptible to infection with poliovirus P1/Mahoney, but not with polioviruses P2/Lansing and P3/Leon, due to lack of binding.

Scientists: Engage the Public!

Scientists must communicate about science with public audiences to promote an understanding of complex issues that we face in our technologically advanced society. Some scientists may be concerned about a social stigma or "Sagan effect" associated with participating in public communication. Recent research in the social sciences indicates that public communication by scientists is not a niche activity but is widely done and can be beneficial to a scientist's career.

Major and minor group rhinoviruses elicit differential signaling and cytokine responses as a function of receptor-mediated signal transduction.

Major- and minor-group human rhinoviruses (HRV) enter their host by binding to the cell surface molecules ICAM-1 and LDL-R, respectively, which are present on both macrophages and epithelial cells. Although epithelial cells are the primary site of productive HRV infection, previous studies have implicated macrophages in establishing the cytokine dysregulation that occurs during rhinovirus-induced asthma exacerbations. Analysis of the transcriptome of primary human macrophages exposed to major- and minor-group HRV demonstrated differential gene expression.

Science should be in the public domain.

Variants of avian influenza H5N1 virus that are transmitted by the airborne route among ferrets have been identified. The National Science Advisory Board for Biosecurity has advised against publication of the details of the methods used to obtain these viruses and the amino acid changes that lead to transmission in ferrets. This decision is not based on sound scientific principles and risks setting a precedent that will make it easier to put in place highly restrictive regulations on scientific research and publication.

Selection of rhinovirus 1A variants adapted for growth in mouse lung epithelial cells.

Rhinoviruses (RVs) are picornaviruses that are causative agents of the majority of upper respiratory tract infections, or "common colds," in humans. RVs infect both the upper and lower respiratory tract, and in addition to the common cold may also cause pneumonia, complications in patients with chronic lung diseases such as cystic fibrosis, and asthma exacerbations. Convenient animal models are not available to study the pathogenesis of rhinovirus-induced illness.

Components of the multifactor complex needed for internal initiation by the IRES of hepatitis C virus in Saccharomyces cerevisiae.

Interaction between the 40S ribosomal subunit and the IRES of hepatitis C virus (HCV) is thought to be independent of initiation proteins, while joining of the 60S ribosomal subunit, and initiation of translation is dependent upon components of the translation machinery. An established in vivo functional assay for internal initiation mediated by the HCV IRES was used to identify proteins needed for IRES dependent translation in Saccharomyces cerevisiae strains possessing alterations of the translation machinery. Internal initiation dependent upon the HCV IRES was abrogated in strains lacking eIF5B, and reduced in strains with altered eIF3, either lacking the Hcr1p subunit, a component of eIF3 not previously known to interact with HCV RNA, or possessing an amino acid change in the Rpg1p subunit.

Cleavage of IPS-1 in cells infected with human rhinovirus.

Rhinoviruses are prevalent human pathogens that are associated with life-threatening acute asthma exacerbations. The innate immune response to rhinovirus infection, which may play an important role in virus-induced asthma induction, has not been comprehensively investigated. We examined the innate immune response in cells infected with human rhinovirus 1a (HRV1a).

RIG-I is cleaved during picornavirus infection.

The innate immune system senses RNA virus infections through membrane-bound Toll-like receptors or the cytoplasmic proteins RIG-I and MDA-5. RIG-I is believed to recognize the 5'-triphosphate present on many viral RNAs, and hence is important for sensing infections by paramyxoviruses, influenza viruses, rhabdoviruses, and flaviviruses. MDA-5 recognizes dsRNA, and senses infection with picornaviruses, whose RNA 5'-ends are linked to a viral protein, VPg, not a 5'-triphosphate.

Functions of the cytoplasmic RNA sensors RIG-I and MDA-5: key regulators of innate immunity.

The innate immune system responds within minutes of infection to produce type I interferons and pro-inflammatory cytokines. Interferons induce the synthesis of cell proteins with antiviral activity, and also shape the adaptive immune response by priming T cells. Despite the discovery of interferons over 50 years ago, only recently have we begun to understand how cells sense the presence of a virus infection.

Proteinase 2Apro is essential for enterovirus replication in type I interferon-treated cells.

The Picornaviridae family comprises a diverse group of small RNA viruses that cause a variety of human and animal diseases. Some of these viruses are known to induce cleavage of components of the innate immune system and to inhibit steps in the interferon pathway that lead to the production of type I interferon. There has been no study of the effect of picornaviral infection on the events that occur after interferons have been produced.

Enterovirus 70 receptor utilization is controlled by capsid residues that also regulate host range and cytopathogenicity.

Enterovirus type 70, an etiologic agent of acute hemorrhagic conjunctivitis, may bind different cellular receptors depending on cell type. To understand how EV70-receptor interaction is controlled, we studied two variants of the virus with distinct receptor utilization. EV70-Rmk, derived by passage in rhesus monkey kidney cells, replicates poorly in HeLa cells and does not cause cytopathic effects.

MDA-5 is cleaved in poliovirus-infected cells.

Infections with RNA viruses are sensed by the innate immune system through membrane-bound Toll-like receptors or the cytoplasmic RNA helicases RIG-I and MDA-5. It is believed that MDA-5 is crucial for sensing infections by picornaviruses, but there have been no studies on the role of this protein during infection with poliovirus, the prototypic picornavirus. Beginning at 4 h postinfection, MDA-5 protein is degraded in poliovirus-infected cells.

Age-dependent poliovirus replication in the mouse central nervous system is determined by internal ribosome entry site-mediated translation.

Mouse cells are not permissive for the replication of human rhinovirus type 2 (HRV2). To determine the role of the HRV2 internal ribosome entry site (IRES) in determining species specificity, a recombinant poliovirus (P1/HRV2) was constructed by substituting the poliovirus IRES with the IRES from HRV2. This recombinant virus replicated in all human and murine cell lines examined, demonstrating that the HRV2 IRES does not limit viral replication in transformed murine cells.

One hundred years of poliovirus pathogenesis.

Poliovirus was first isolated nearly 100 years ago in a landmark experiment that established the viral etiology of poliomyelitis. This discovery stimulated investigation of the pathogenesis of poliomyelitis in many laboratories. Nearly 50 years later, when two effective poliovirus vaccines were developed, the impetus to study poliovirus pathogenesis waned.

Hepatitis C virus internal ribosome entry site-dependent translation in Saccharomyces cerevisiae is independent of polypyrimidine tract-binding protein, poly(rC)-binding protein 2, and La protein.

Translation initiation of some viral and cellular mRNAs occurs by ribosome binding to an internal ribosome entry site (IRES). Internal initiation mediated by the hepatitis C virus (HCV) IRES in Saccharomyces cerevisiae was shown by translation of the second open reading frame in a bicistronic mRNA. Introduction of a single base change in the HCV IRES, known to abrogate internal initiation in mammalian cells, abolished translation of the second open reading frame.

Amino acid changes in proteins 2B and 3A mediate rhinovirus type 39 growth in mouse cells.

Many steps of viral replication are dependent on the interaction of viral proteins with host cell components. To identify rhinovirus proteins involved in such interactions, human rhinovirus 39 (HRV39), a virus unable to replicate in mouse cells, was adapted to efficient growth in mouse cells producing the viral receptor ICAM-1 (ICAM-L cells). Amino acid changes were identified in the 2B and 3A proteins of the adapted virus, RV39/L.

Poliovirus tropism and attenuation are determined after internal ribosome entry.

Poliovirus replication is limited to a few organs, including the brain and spinal cord. This restricted tropism may be a consequence of organ-specific differences in translation initiation by the poliovirus internal ribosome entry site (IRES). A C-to-U mutation at base 472 in the IRES of the Sabin type 3 poliovirus vaccine strain, known to attenuate neurovirulence, may further restrict tropism by eliminating viral replication in the CNS.