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The genome of an RNA virus can be said to be either positive-sense, also known as a "plus-strand", or negative-sense, also known as a "minus-strand". In most cases, the terms "sense" and "strand" are used interchangeably, making terms such as "positive-strand" equivalent to "positive-sense", and "plus-strand" equivalent to "plus-sense".
Positive-strand RNA viruses encode an RNA-dependent RNA polymerase (RdRp) which is used during replication of the genome to synthesize a negative-sense antigenome that is then used as a template to create a new positive-sense viral genome. Positive-strand RNA viruses are divided between the phyla Kitrinoviricota, Lenarviricota, and Pisuviricota ...
During replication of the viral genome, RdRp synthesizes a positive-sense antigenome that it uses as a template to create genomic negative-sense RNA. Negative-strand RNA viruses also share a number of other characteristics: most contain a viral envelope that surrounds the capsid, which encases the viral genome, −ssRNA virus genomes are ...
Negative-sense viral RNA is complementary to mRNA and thus must be converted to positive-sense RNA by an RNA-dependent RNA polymerase before translation. Purified RNA of a positive-sense virus can directly cause infection though it may be less infectious than the whole virus particle. In contrast, purified RNA of a negative-sense virus is not ...
A positive-sense genome copy that serves as template for production of the negative-strand genome is then produced. Replication is within the cytoplasm. Viruses with segmented genomes for which replication occurs in the cytoplasm and for which the viral RNA-dependent RNA polymerase produces monocistronic mRNAs from each genome segment.
Baltimore classification groups viruses together based on their manner of mRNA synthesis. Characteristics directly related to this include whether the genome is made of deoxyribonucleic acid (DNA) or ribonucleic acid (RNA), the strandedness of the genome, which can be either single- or double-stranded, and the sense of a single-stranded genome, which is either positive or negative.
For parvoviruses, either the positive or negative sense strand may be packaged into capsids, varying from virus to virus. [16] [17] Nearly all ssDNA viruses have positive sense genomes, but a few exceptions and peculiarities exist. The family Anelloviridae is the only ssDNA family whose members have negative sense genomes, which are circular. [15]
The virus affects both meat production and egg production and causes substantial economic loss. [132] In chickens, infectious bronchitis virus targets not only the respiratory tract but also the urogenital tract. The virus can spread to different organs throughout the chicken. [131] The virus is transmitted by aerosol and food contaminated by ...