Published on 28 May 2026

On the trail of pestiviruses: deciphering their immune evasion strategies using fluorescent markers

With the development of the GFP-tagged pestivirus, we now have a new tool at our disposal to study the interactions between the virus and its host, and thus to understand the reasons behind these viruses’ success in their host population.

Pestiviruses, such as the bovine viral diarrhoea virus (BVDV) or the classical swine fever virus, cause serious problems on livestock farms, leading to animal welfare issues and economic losses. At the same time, BVDV is a unique model for studying the interaction of viruses with the host’s innate immune system, as it is able to induce persistent infections characterised by a complete immunotolerance to the infecting virus strain.

• Why is this study important?

  In this study, we established the construction of pestiviruses, which will allow us to generate new variants to further study the pathogenesis of pestiviruses. Using this method, we also generated a variant tagged with a green fluorescent protein (GFP) as a new tool.

• Study description

  Using TAR cloning (‘transformation-associated recombination), we constructed various pestiviruses in which the envelope glycoprotein E^rns was modified without losing its infectivity.

  E^rns is a truly fascinating virus protein: on the one hand, it is part of the virus structure, but on the other, it is also an endoribonuclease (RNase), which is secreted from the cells in a soluble form. This RNase works like a guard and removes incorrectly located viral RNA before the host’s innate immune system recognises it. Therefore, the host cells do not respond by producing the antiviral messenger substance interferon (IFN), which allows the pestiviruses to evade the host’s immune response.

• What are the key findings?

  In our study we used the Bungowannah pestivirus (BuPV) for cloning as it is tolerant of mutations and can infect various types of cell. We also produced a BuPV in which the E^rns was tagged with a GFP. This ‘BuPV GFP-E^rns’ was stable over several infection cycles and its RNase function was retained. This confirmed that the GFP tag did not impair the most important biological activity of E^rns.

• What next?

  It is still not yet entirely clear where exactly E^rns works, whether in the extracellular space or in an intracellular compartment, or even at the interface between infected and non-infected cells. The latter is particularly relevant in plasmacytoid dendritic cells (pDCs) – the most important IFN-producing cells of the body – but the exact mechanism involved is not yet known. Using our GFP-tagged pestivirus, we hope to find out more about the cellular mechanisms of E^rns in the viral life cycle.

Title and link to the publication

«GFP-Tagged E^rns in Bungowannah Pestivirus: A Tool for Viral Tracking and Functional Studies» GFP-Tagged E^rns in Bungowannah Pestivirus: A Tool for Viral Tracking and Functional Studies | MDPI

Authors

Sara Ezzat and Matthias Schweizer

Further information

• IVI Eradication of bovine viral diarrhoea (BVD) in Switzerland
• IVI Epizootic disease diagnostics – Ruminants
• BLV  Bovine viral diarrhoea BVD (auf deutsch)

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