Biology Reference
In-Depth Information
In the USA, there are four levels of biosafety, and each is associ-
ated with specifi c rules geared toward safety issues and the reduction
of personal contamination or infection. These are the biosafety levels:
Level 1: This level covers well-characterized agents that do not
consistently cause disease in immunocompetent adult humans.
They pose minimal potential hazards to laboratory personnel
and/or the environment. Examples of a BSL-1 vector are
adeno-associated virus and canine adenovirus.
Level 2: Level 2 BSL covers well-characterized agents that
pose a moderate health hazard to laboratory personnel and/or
the environment. For this class, preventative and therapeutic
interventions are often available. Examples of BSL-2 vectors
include adenovirus and lentivirus (non-HIV pseudotypes);
HSV is considered BSL-2 by our institution until each batch
prepared is tested and confi rmed to not contain replication-
competent revertants, after which we are allowed to use BSL-1
procedures.
Level 3: This BSL covers indigenous or exotic agents that may
cause serious or potentially lethal disease to humans though
inhalation. Preventative or therapeutic interventions may be
available. Examples of viruses that fall under this category
include anthrax and severe acute respiratory syndrome (SARS)
coronavirus.
Level 4: Level 4 BSL agents are dangerous and exotic, with a
high individual risk for life-threatening disease. Preventative
and therapeutic interventions are not usually available for these
viruses and these are not used for biobehavioral experiments.
2.3 Animal Care
and Use Committees
Another important issue to consider is the use of viral vectors in
vivo. The necessity to house animals treated with viral vectors for
an extended period presents a number of unique problems in com-
parison to in vitro uses of viral vectors in a standard laboratory
environment. In our experience, institutional animal care and use
committees now examine experimental plans involving viral vec-
tors much more closely than they did just a few years ago. As with
biosafety issues, there must be detailed plans in place for how to
handle animals that have received virus, since the animal itself may
be a source of subsequent transfer of transgenes to other animals,
the environment, or laboratory personnel via contact with the ani-
mal. Protocols for managing soiled bedding that may contain
shedded virus or injuries to other animals or personnel via bites or
scratches must be carefully documented. In some cases, animals
treated with viral vectors must be housed separately, especially with
BSL-2 vectors. The soiled bedding may require sterilization prior
to disposal and careful documentation of the type of vector used in
each animal is generally required so that personnel in contact with
the animals can readily determine the nature of their own exposure
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