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Plant virus transmission strategies in insect vectors. Plant viruses need to be transmitted by a vector, most often insects such as leafhoppers. One class of viruses, the Rhabdoviridae, has been proposed to actually be insect viruses that have evolved to replicate in plants. The chosen insect vector of a plant virus will often be the ...
PSTVd was the first pathogen of a eukaryotic organism for which the complete molecular structure has been established. Over thirty plant diseases have since been identified as viroid-, not virus-caused, as had been assumed. [88] [93] Four additional viroids or viroid-like RNA particles were discovered between 2009 and 2015. [86]
Vertebrates (including mammals and humans), invertebrates, plants, fungi and protozoans serve as natural hosts. [2] [3] [4] Diseases associated with member viruses include rabies encephalitis caused by the rabies virus, and flu-like symptoms in humans caused by vesiculoviruses.
Bunyaviruses belong to the fifth group of the Baltimore classification system, which includes viruses with a negative-sense, single-stranded RNA genome. They have an enveloped, spherical virion. Though generally found in arthropods or rodents, certain viruses in this order occasionally infect humans. Some of them also infect plants. [6]
When control of plant virus infections is considered economical, for perennial fruits, for example, efforts are concentrated on killing the vectors and removing alternate hosts such as weeds. [13]: 802 Plant viruses cannot infect humans and other animals because they can reproduce only in living plant cells. [13]: 799–807
Since viruses are obligate intracellular parasites they must develop direct methods of transmission, between hosts, in order to survive. The mobility of animals increases the mechanisms of viral transmission that have evolved, whereas plants remain immobile, and thus plant viruses must rely on environmental factors to be transmitted between hosts.
However, there are many cases where mycoviruses are grouped together with plant viruses. For example, CHV1 showed phylogenetic relatedness to the ssRNA genus Potyvirus, [25] and some ssRNA viruses, which were assumed to confer hypovirulence or debilitation, were often found to be more closely related to plant viruses than to other mycoviruses. [1]
For example, the human body louse transmits the bacterium Rickettsia prowazekii which causes epidemic typhus. Although invertebrate-transmitted diseases pose a particular threat on the continents of Africa, Asia and South America, there is one way of controlling invertebrate-borne diseases, which is by controlling the invertebrate vector.