Risk assessment of insect-specific viruses (ISV)

Viruses that can only replicate in insect cells, but not in vertebrates, other invertebrates, and plants, are called insect-specific viruses (ISV) Infected insects can be Vectors serve to transmit viruses to plants, animals, and humans. So-called arthropod-borne (arbo)viruses often have their evolutionary origin in ISVs and can cause serious diseases in humans, such as dengue or yellow fever. As ISVs are increasingly becoming the focus of (genetic engineering) research projects, the ZKBS has issued a statement on the criteria for risk assessment.

Both for economically relevant Beneficial insects ISVs can pose an economic threat to both insects in the food and feed sector. Baculoviruses, for example, are used for pest control in agriculture and forestry. Newer methods of metagenomic analysis are increasingly detecting previously undiscovered viruses. Most of these new ISVs have not (yet) manifested themselves through symptoms of disease in infected hosts.

Often little or no information is available on the biology of new ISVs, such as their host range, pathogenicity, and mode of transmission. However, it can be assumed that the majority of the previously little-described ISVs are not pathogenic to their host. Therefore, the ZKBS considers it disproportionate to preemptively assign all ISVs that have not yet been fully characterized to risk group 2. Instead, the ZKBS establishes criteria for the evaluation and classification of ISVs as donor or recipient organisms for genetic engineering work. A key factor in classifying ISVs into risk groups is whether a risk to beneficial insects is to be expected if these viruses escape into the environment. In the absence of concrete data, the degree of relatedness to known entomopathic viruses can also be used to estimate potential pathogenicity.

ISV are the Risk group 1 to be assigned if data demonstrate apathogenicity for potential host insects or if there is no indication of pathogenicity of the corresponding viruses when viral nucleic acid fragments are detected in complex environmental samples or metagenomes of beneficial insects living freely in Germany. The same applies if pathogenicity for non-beneficial insects is present, but the viruses are already widespread in Germany or directly bordering countries. Representatives of the baculovirus family (Baculoviridae) are generally assigned to risk group 1. If the non-beneficial insect hosts of specific ISVs are not widespread in Germany or directly bordering countries, or if vectors (e.g. a mite) that may be necessary for the transmission of the ISV to non-beneficial insects are not widespread in Germany or directly bordering countries, the specific ISV is also assigned to risk group 1.

ISV are in the Risk group 2 to be classified as risk group 2 if they are pathogenic for beneficial insects found in the wild in Germany or if there is evidence of such pathogenicity. Classification in risk group 2 also exists if pathogenicity for non-beneficial insects common in Germany is present and the ISV is not yet widespread in Germany, but the vectors necessary for transmission are.

When performing genetic engineering work with ISVs whose hosts occur in Germany and neighboring countries, appropriate measures must be taken to reliably prevent escape, and in accordance with the GenTSV, the ingress of vectors of genetically modified organisms (e.g., arthropods) must be prevented. This can be ensured, for example, by the following measures:

• Securing openings (e.g. windows, door locks, door gaps) with insect protection gauze, brushes or rubber lips
• windows that cannot be opened
• Use of door locks with locking cylinders
• controlled access, secured e.g. by an air shower or an insect screen
• Capturing and killing insects found in the laboratory (preparing insecticide, setting up insect traps)

The ZKBS statement can be found at File number 45310.0120 can be retrieved.