Citrus psorosis virus (CPsV)

A Viral Biorealm page on the family Citrus psorosis virus (CPsV)

Apis mellifera, a common host of Kashmir bee virus. [1].

Baltimore Classification

Group V: (-) sense single-stranded RNA viruses

Higher order categories

Family: Ophioviridae
Genus: Ophiovirus

Description and Significance

Citrus psorosis virus (CpsV) is considered to be the most infectious and problematic virus pathogen of citrus plants worldwide, mostly in citrus producing countries such as North, South American and the Mediterranean. CpsV is the oldest reported citrus virus, first reported symptoms in 1896 and known viral etiology in 1933. There are a variety of different strains and symptoms which vary from mild, type 'A,' to severe, type 'B.' Symptoms can be exhibited in leaves, fruit, bark, trunk and branches. Leaf infection displays chlorotic flecks, or a decrease in chlorophyll/healthy coloring, mottling and spots; fruit may show ring-like chlorotic areas[1]. Chlorosis decreases plant's efficiency to perform photosynthesis, or ability to produce carbohydrates necessary for energy, organism support and growth[1]. The most common symptom of psorosis is deterioration of bark, such as flaking or scaling on trunk and limbs. Early stages of this deterioration are marked by blisters or bubbles which grow and later result in patches.

Citrus plants which have been reported to exhibit this virus are grapefuit, mandarin, orange and tangerine, lemon, pomelo and lime. It is economically important in the production and distribution of citrus fruit.

Genome Structure

Three species of ssRNA have been detected in the Citrus psorosis virus (CpsV), each of which is contained in a capsid made up of the same proteins. The three genomic ssRNAs are 8184, 1644 and 1454 nucleotides in length. ORF 1 of RNA1, is located at 5’ end of the negative strand, and translates for a 280 kDa protein characteristic to that of RNA-dependent RNA polymerase. Separated from ORF1 by 109 nucleotides is ORF2 of RNA1, which encodes a 24 kDa protein which has no homologues in the database and performs unknown functions. Conversely, RNA2 has a single ORF encoding a novel protein of 54kDa which resembles a nuclear localization signal. In RNA2, specifically the 3’ terminal untranslated region, there is a known polydenylation signal. RNA3 has one ORF which encodes for its coat protein. The three RNAs have similar 3’ terminal regions, however, extremely differing 5’terminal regions. The virions are circular with a suggested “panhandle structure” which is formed by the base pairs of the terminal regions in each RNA strand; the first 75 nucleotides of the RNA1 termini exhibit 41% complementary components. However, results vary throughout many studies of secondary structure predictions.

References

Example: Weir, Jerry P. " Genomic Organization and Evolution of the Human Herpesviruses." Virus Genes 16.1 (1998): 85-93.

Page authored for BIOL 375 Virology, September 2010