Cannabis Virology Investigation Past and Present
Professor DeBacco
Research Article
Miotti, N., Passera, A., Ratti, C., Dall’Ara, M., & Casati, P. (2023). A Guide to Cannabis Virology: From the Virome Investigation to the Development of Viral Biotechnological Tools. Viruses, 15(7), 1532.
https://www.mdpi.com/1999-4915/15/7/1532


Virus Taxonomy Basics
Virus names as may be recognized are based on the plant species that it was first detected in.
This does not mean that it is the only plant the virus can infect.
It also does not even mean it is most virlent in that plant.
But it does allow for (relatively) easy system for identification.
Virus Taxonomy
Discovering a virus and naming it may seem like a standard process it is increasing in complexity.
This is important due to the exponentially increasing number of new viruses discovered by next-generation sequencing methods.
It is these new methods of discovery that when applied to some previously discovered viruses may lead to a change in classification which can add confusion.
Reported Viruses and Viroid in Cannabis Sativa
List of the known concerns for cannabis growers when it comes to viruses and viroids.
Visual Diagnosis of a Virus
Viruses in general provide a set of visual symptoms.

Often seeing leaves with mottling, mosaic or wrinkling is an indication of a viral infection.

However, it takes a lab to screen for and identify the exact type of virus
Why Knowing the Virus is Important
Regardless of the virus there is little the grower can do, so why bother getting it identified?
Justification for going through the hassle of getting a virus identified is important to know how it may have gotten there (Ex. insect vectors) and what the residual may be and what is the odds of seed transmission.
Knowing the Virus Provides a Plan
Once you know what virus (or viruses) you may have, you can better develop a plan for prevention going forward.
Improved Understanding
A better understanding of viral vectors and the genome of the cannabis plant has also resulted in the identification of regulatory genes responsible for valuable medical or agronomical phenotypic traits.
CRISPR/Cas9 can be used to target gene editing just like other agricultural crops.

Threat Levels Concept
While there are many viruses that can infect cannabis, the authors have proposed a threat level categorization for cannabis cultivators.
Highest Level = A
Lowest Level = D
While most of the currently available information is based on crops other than cannabis it still can provide a good starting point.
*Note: The following Level descriptions are direct quote from the research paper.
Level A (Highest Level)
Level A of our classification includes viruses detected in the field/or greenhouse conditions, toward which, an epidemiological survey is active. These viruses can spread horizontally by vector or by agamic propagation and have been associated with significant yield losses in C. sativa as well as in other economically relevant crops.
Example Virus in this Level… BCTV, LCV and HLVd
Level B (Second Highest of the Four Levels)
Level B includes viruses of which no recent reports of natural infection in open field or greenhouse plants are available, but whose ability to infect C. sativa and induce symptoms has been proven through experimental inoculations in protected environments (Table 2). Most of these viruses are known to possess a vector in other well-studied and -characterized crops, but these vectors have yet to be verified in C. sativa cultivation contexts.
Example Virus in this Level… AMV, ArMV, BBWV, CMV, PVX, PVY, RRSV, and TSWV.
Level C
The members of this level are viruses detected in symptomatic cannabis plants from fields or greenhouses; however, none of these have been inferred as virulence determinants, so, to date, it is impossible to define them as pathogenic or asymptomatic.
Example Virus in this Level… CYVaV, GLPV, OULV, and TSV
Level D (Lowest Level)
Viruses detected both in symptomatic and asymptomatic C. sativa are categorized at this level. No correlation has been established between viral infection and symptom development, whereas persistent infection and wide distribution are the main characteristics of these viral agents. According to these criteria, level D viruses should not be considered as a threat to C. sativa production.
Example Virus in this Level… CanCV and CasaMV1
Grower Friendly System
This threat level classification makes it easier for cultivators to know when they get a virus identified what their level of concern should be and also possible how to prevent it from occurring in the future.
The intention is to provide the key “need to know” information to a cultivator without the complete virology.

Link to Lecture Slides: https://drive.google.com/file/d/1I2XF...

*Due to the description character limit the full work cited for "Cannabis Virology Investigation Past and Present" can be viewed at..