Nucleopolyhedrovirus: scanning electron microscopy technique

Abstract

Neotropical Entomology 35(6):787-790 (2006) Nucleopolyhedrovirus: Técnica de Microscopia Eletrônica de Varredura RESUMO -Um método simples foi desenvolvido para se estudar a forma geométrica do Bombyx mori Nucleopolyhedrovirus múltiplo, BmMNPV, para microscopia eletrônica de varredura. O vírus, pertencente à Família Baculoviridae, foi obtido do fi ltrado, do inóculo e da hemolinfa de lagartas de Bombyx mori (L.) (Lepidoptera: Bombycidae) infectadas. O material foi colocado diretamente sobre o suporte de varredura, onde previamente foi aderida uma fi ta de cobre. Após secagem e metalização com carbono e ouro, o vírus foi analisado ao microscópio de varredura. Os poliedros apresentaramse com as faces lisas, perfeitamente defi nidas, possibilitando a análise matemática que o identifi cou como um octaedro truncado. A forma do poliedro pode apresentar valor taxonômico, uma vez que ela é específi ca para cada linhagem viral. PALAVRAS-CHAVE: Baculovírus, Bombyx mori, BmMNPV, poliedro, octaedro truncado ABSTRACT -A simplifi ed methodology was developed to study the geometric form of multiple Bombyx mori Nucleopolyhedrovirus by scanning electron microscopy. The virus belongs to Baculoviridae family and was isolated from the silkworm Bombyx mori (L.) (Lepidoptera: Bombycidae). The polyhedra of Nucleopolyhedrovirus were obtained from the fi ltrate, inoculum and hemolymph of the silkworm experimentally infected with nuclear polyhedra. This material was placed on stubs, where a copper tape was previously adhered. After dry at room temperature the virus was covered with carbon and gold. Scanning electron microscopy analysis reveled a well defi ned morphology for the polyhedra of multiple Bombyx mori Nucleopolyhedrovirus, making possible the mathematical study that identifi ed it as a truncated octahedron. The form of the polyhedron can present taxonomic value, once it is specifi c for each viral lineage.KEY WORDS: Baculovirus, Bombyx mori, BmMNPV, polyhedra, truncated octahedron Nucleopolyhedrovirus (NPV) is an important entomopathogenic virus belonging to Baculoviridae family. It is made up of double stranded DNA molecule, associated with proteins of the capsid, forming the nucleocapsid. Two different subgroups are recognized for NPV: the occlusion derived virions and the budded virus. These virion subgroups have different functions in the infection cycle. The occluded subgroups could be divided into two subgroups: those containing one nucleocapsid per virion are referred to as single-capsid NPVs (SNPVs), whereas those containing multiple nucleocapsids per virion are known as multiple NPVs (MNPVs) (Murphy et al. 1995, Blissard 1996.Nucleocapsid and envelope constitutes the virion or infectious particle. In NPV several virions are contained in a protein structure, named occlusion body or polyhedron (Adams & McClintock 1991, Murphy et al. 1995, Blissard 1996. Polyhedra are stable structures that can persist for long time in the environment, where they are commonly found on the surface of the plants or in the soil. In the so...

Cytopathology of Bombyx mori (Lepidoptera: Bombycidae) silk gland caused by multiple nucleopolyhedrovirus

“…In the electron micrographs, the polyhedron envelope has a membrane-like structure, as shown in Figure 6. The BmMNPV polyhedron ranges from 2.5 to 4.5 µm in diameter and has a truncated octahedron geometric shape (Torquato et al, 2006b). Hong et al (2000) suggest the existence of genetic variation in the polyhedron geometric shape of BmNPV and that this is specific for each viral lineage.…”

“…Reddy and Locke (1990) investigated the behavior of gold particles on the BL of Calpodes ethlius (Lepidoptera: Hesperiidae) larvae, and showed that particles smaller than 15 nm crossed the BL of certain tissues, such as fatty, epidermal and pericardial ones, whereas particles larger than 6 nm were retained in the silk gland, in the Malpighian tubule and in the muscle BL. BmMNPV virions have an approximate mean diameter of 95 nm and length of 315 nm (Torquato et al, 2006b), making the passage of BV through the silk gland BL difficult.…”

Controle e prevenção da calcinose branca em Bombyx mori L. (Lepidoptera: Bombycidae)

“…Geralmente, oscilações de temperatura, alimentação com folhas de má qualidade e irregularidade nos horários de alimentação podem favorecer a maior incidência da virose (Hanada;Watanabe, 1986). Um vírus do gênero Alphabaculovirus chamado de nucleopolyhedrovirus, subgrupo múltiplo de B. mori (BmMNPV), foi isolado no estado do Paraná e apresenta-se altamente patogênico, em função da presença de vários nucleocapsídeos por vírion e elevada mortalidade em curto espaço de tempo Torquato et al, 2006).…”

Evolution of nanoparticle-induced distortion on viral polyhedra

“…Viral morphology with and without LASN treatment was elucidated following SEM [12,13] with minor modifications in the protocol. First, 0.5 mg of dry NP powder was added in 1.5 ml of ethanol and made an ethanolic solution of LASN.…”