When retroviruses have integrated their own genome into the germ line, their genome is passed on to a following generation. These endogenous retroviruses (ERVs), contrasted with exogenous ones, now make up 5-8% of the human genome.[7] Most insertions have no known function and are often referred to as "junk DNA". However, many endogenous retroviruses play important roles in host biology, such as control of gene transcription, cell fusion during placental development in the course of the germination of an embryo, and resistance to exogenous retroviral infection. Endogenous retroviruses have also received special attention in the research of immunology-related pathologies, such as autoimmune diseases like multiple sclerosis, although endogenous retroviruses have not yet been proven to play any causal role in this class of disease.[8] While transcription was classically thought to occur only from DNA to RNA, reverse transcriptase transcribes RNA into DNA. The term "retro" in retrovirus refers to ...
The hepatitis envelope proteins are composed of subunits made from the viral preS1, preS2, and S genes. The L (for "large") envelope protein contains all three subunits. The M (for "medium") protein contains only preS2 and S. The S (for "small") protein contains only S. The genome portions encoding these envelope protein subuntis share both the same frame and the same stop codon (generating nested transcripts on a single open reading frame. The pre-S1 is encoded first (closest to the 5' end), followed directly by the pre-S2 and the S. When a transcript is made from the beginning of the pre-S1 region, all three genes are included in the transcript and the L protein is produced. When the transcript starts after the pro-S1 at the beginning of the pre-S2 the final protein contains the pre-S2 and S subunits only and therefore is an M protein. The smallest envelope protein containing just the S subunit is made most because it is encoded closest to the 3' end and comes from the shortest transcript. ...
Viruses in Betanodavirus are non-enveloped, with icosahedral geometries, and T=3 symmetry. The diameter is around 30 nm. Genomes are linear and segmented, bipartite, around 21.4kb in length.[8]. The crystal structure of a betanodavirus- T=3 Grouper nervous necrosis virus (GNNV)-like particle has been determined by X-ray crystallography. The virus-like particle contains 180 subunits of the capsid protein, and each capsid protein (CP) shows three major domains: (i) the N-terminal arm, an inter-subunit extension at the inner surface; (ii) the shell domain (S-domain), a jelly-roll structure; and (iii) the protrusion domain (P-domain) formed by three-fold trimeric protrusions. [10]. ...
Nucleic acid analysis suggests a very long association of the viruses with the wasps (greater than 70 million years).. Two proposals have been advanced for how the wasp/virus association developed. The first suggests that the virus is derived from wasp genes. Many parasitoids that do not use PDVs inject proteins that provide many of the same functions, that is, a suppression of the immune response to the parasite egg. In this model, the braconid and ichneumonid wasps packaged genes for these functions into the viruses-essentially creating a gene-transfer system that results in the caterpillar producing the immune-suppressing factors. In this scenario, the PDV structural proteins (capsids) were probably "borrowed" from existing viruses.. The alternative proposal suggests that ancestral wasps developed a beneficial association with an existing virus that eventually led to the integration of the virus into the wasp's genome. Following integration, the genes responsible for virus replication and the ...
Louis Pasteur was unable to find a causative agent for rabies and speculated about a pathogen too small to be detected using a microscope.[21] In 1884, the French microbiologist Charles Chamberland invented a filter (known today as the Chamberland filter or the Pasteur-Chamberland filter) with pores smaller than bacteria. Thus, he could pass a solution containing bacteria through the filter and completely remove them from the solution.[22] In 1892, the Russian biologist Dmitri Ivanovsky used this filter to study what is now known as the tobacco mosaic virus. His experiments showed that crushed leaf extracts from infected tobacco plants remain infectious after filtration. Ivanovsky suggested the infection might be caused by a toxin produced by bacteria, but did not pursue the idea.[23] At the time it was thought that all infectious agents could be retained by filters and grown on a nutrient medium - this was part of the germ theory of disease.[2] In 1898, the Dutch microbiologist Martinus ...
Despite his other successes, Louis Pasteur (1822-1895) was unable to find a causative agent for rabies and speculated about a pathogen too small to be detected using a microscope.[1] In 1884, the French microbiologist Charles Chamberland (1851-1931) invented a filter - known today as the Chamberland filter - that had pores smaller than bacteria. Thus, he could pass a solution containing bacteria through the filter and completely remove them from the solution.[2] In 1876, Adolf Mayer, who directed the Agricultural Experimental Station in Wageningen was the first to show that what he called "Tobacco Mosaic Disease" was infectious, he thought that it was caused by either a toxin or a very small bacterium. Later, in 1892, the Russian biologist Dmitry Ivanovsky (1864-1920) used a Chamberland filter to study what is now known as the tobacco mosaic virus. His experiments showed that crushed leaf extracts from infected tobacco plants remain infectious after filtration. Ivanovsky suggested the infection ...
The Birnaviridae genome encodes several proteins: Birnaviridae RNA-directed RNA polymerase (VP1), which lacks the highly conserved Gly-Asp-Asp (GDD) sequence, a component of the proposed catalytic site of this enzyme family that exists in the conserved motif VI of the palm domain of other RNA-directed RNA polymerases.[3] The large RNA segment, segment A, of birnaviruses codes for a polyprotein (N-VP2-VP4-VP3-C) [4] that is processed into the major structural proteins of the virion: VP2, VP3 (a minor structural component of the virus), and into the putative protease VP4.[4] VP4 protein is involved in generating VP2 and VP3.[4] recombinant VP3 is more immunogenic than recombinant VP2.[5] Infectious pancreatic necrosis virus (IPNV), a birnavirus, is an important pathogen in fish farms. Analyses of viral proteins showed that VP2 is the major structural and immunogenic polypeptide of the virus.[6][7] All neutralizing monoclonal antibodies are specific to VP2 and bind to continuous or discontinuous ...
弯曲病毒科 Flexiviridae. *光滑病毒科 Leviviridae ...
弯曲病毒科 Flexiviridae. *光滑病毒科 Leviviridae ...
In 2004 it was placed in the Carlavirus genus within the family Flexiviridae. When that family was split in 2009, Carlavirus ... "The new plant family Flexiviridae and assessment of molecular criteria for species demarcation". Arch Virol. 149 (5): 1045-1060 ...
"The new plant family Flexiviridae and assessment of molecular criteria for species demarcation". Arch Virol. 149 (5): 1045-60. ...
... a novel member of the Flexiviridae family". Archives of Virology. 150 (9): 1715-1727. doi:10.1007/s00705-005-0567-0. PMID ...
May 2004). "The new plant virus family Flexiviridae and assessment of molecular criteria for species demarcation". Arch. Virol ... two-way comparisons between comprehensive sets of sequences from the families Flexiviridae and Potyviridae that have helped ...
... it was placed in the Flexiviridae family, having previously been unassigned. The current position in the 9th report (2009) as a ... The new plant virus family Flexiviridae and assessment of molecular criteria for species demarcation". Archives of Virology. ... genus of the family Betaflexiviridae derives from the subsequent subdivision of Flexiviridae. Group: ssRNA(+) Order: ...
The new plant virus family Flexiviridae and assessment of molecular criteria for species demarcation". Archives of Virology. ...
... proposed type member of a new genus in the family Flexiviridae". Archives of Virology. 153 (7): 1263-70. doi:10.1007/s00705-008 ...
... plant pathogenic virus of the family Flexiviridae Odontoglossum ringspot virus, plant pathogenic virus Papaya ringspot virus, ...
... was a family of viruses named after being filamentous and highly flexible. Members of the family infect plants. In ... Alphaflexiviridae Betaflexiviridae Gammaflexiviridae Deltaflexiviridae Flexiviridae was incertae sedis but the new families are ... 2009, the family was dissolved and replaced with four families, each of which still contain the name flexiviridae: ...
Flexiviridae · Leviviridae · Luteoviridae · Marnaviridae · Narnaviridae · Nodaviridae · Picornaviridae (Enterovirus, Rhinovirus ...