Structure and Expression of Large (+)RNA Genomes of Viruses of Higher Eukaryotes.

Viral positive-sense RNA genomes evolve rapidly due to the high mutation rates during replication and RNA recombination, which allowing the viruses to acquire and modify genes for their adaptation. The size of RNA genome is limited by several factors, including low fidelity of RNA polymerases and packaging constraints. However, the 12-kb size limit is exceeded in the two groups of eukaryotic (+)RNA viruses - animal nidoviruses and plant closteroviruses.

Enhancing Capsid Proteins Capacity in Plant Virus-Vector Interactions and Virus Transmission.

Vector transmission of plant viruses is basically of two types that depend on the virus helper component proteins or the capsid proteins. A number of plant viruses belonging to disparate groups have developed unusual capsid proteins providing for interactions with the vector. Thus, cauliflower mosaic virus, a plant pararetrovirus, employs a virion associated p3 protein, the major capsid protein, and a helper component for the semi-persistent transmission by aphids.

Nonstructural p26 proteins encoded by the 3'-proximal genes of velariviruses and criniviruses are orthologs.

The 3'-most genes in RNA-2 of the Crinivirus genus members (family Closteroviridae) code for non-structural p26 proteins that share amino acid sequence similarity [Stewart LR, Hwang MS, Falk BW (2009) Virus Res 145:293-299]. In this study, sensitive bioinformatic tools have been used to identify the homologous p26 proteins encoded by the 3' genes in monopartite genomes of the members of Velarivirus, another Closteroviridae genus, and mint vein banding-associated virus, an unassigned member of the family. The p26 proteins showed similarity in their predicted secondary structures, but an amino acid sequence alignment showed no strictly conserved positions, thus indicating a high plasticity of these non-structural proteins.

Molecular Alliance of Lymantria dispar Multiple Nucleopolyhedrovirus and a Short Unmodified Antisense Oligonucleotide of Its Anti-Apoptotic IAP-3 Gene: A Novel Approach for Gypsy Moth Control.

Baculovirus IAP (inhibitor-of-apoptosis) genes originated by capture of host genes. Unmodified short antisense DNA oligonucleotides (oligoDNAs) from baculovirus IAP genes can down-regulate specific gene expression profiles in both baculovirus-free and baculovirus-infected insects. In this study, gypsy moth () larvae infected with multiple nucleopolyhedrovirus (LdMNPV), and LdMNPV-free larvae, were treated with oligoDNA antisense to the RING (really interesting new gene) domain of the LdMNPV gene.

A conserved region in the Closterovirus 1a polyprotein drives extensive remodeling of endoplasmic reticulum membranes and induces motile globules in Nicotiana benthamiana cells.

In infected plant cells, closterovirus replicative polyproteins 1a and 1ab drive membrane remodeling and formation of multivesicular replication platforms. Polyprotein 1a contains a variable Central Region (CR) between the methyltransferase and helicase domains. In a previous study, we have found that transient expression of the Beet yellows virus CR-2 segment (aa 1305-1494) in Nicotiana benthamiana induces the formation of ~1µm mobile globules originating from the ER membranes.