The alphaherpesvirus conserved pUS10 is important for natural infection and its expression is regulated by the conserved Herpesviridae protein kinase (CHPK)

Authors: PONNURAJ, NAGENDRAPRABHU - University Of Illinois; AKBAR, HAJI - University Of Illinois; ARRINGTON, JUSTINE - University Of Illinois; Spatz, Stephen; NAGARAJAN, BALAJI - Virginia Commonwealth University; DESAI, UMESH - University Of Illinois; JAROSINSKI, KEITH - University Of Illinois

Submitted to: PLoS Pathogens
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2023
Publication Date: 2/7/2023
Citation: Ponnuraj, N., Akbar, H., Arrington, J.V., Spatz, S.J., Nagarajan, B., Desai, U.R., Jarosinski, K.W. 2023. The alphaherpesvirus conserved pUS10 is important for natural infection and its expression is regulated by the conserved Herpesviridae protein kinase (CHPK). PLoS Pathogens. 19(2):e1010959. https://doi.org/10.1371/journal.ppat.1010959.
DOI: https://doi.org/10.1371/journal.ppat.1010959

Interpretive Summary: Marek’s disease herpesvirus (MDV) is an important pathogen in the poultry industry. Current vaccines reduce disease but do not protect chickens from infection. Understanding natural infection provides important information for developing potential therapies to protect against Marek’s disease, while also providing a robust natural virus-host model to study herpesvirus pathogenesis. The conserved Herpesviridae protein kinase (CHPK) of MDV is essential for the initiation of natural infection, and we identified the virion protein US10 as a potential target for CHPK during natural infection. Our results showed that MDV CHPK was required for the expression of pUS10 in both cell culture and chickens. Although MDV lacking pUS10 replicated and spread in experimentally infected chickens, it was less virulent, implicating a role of pUS10 in the natural infection of the host. These results emphasize the importance of studying specific viral proteins and their functions during infection of the natural host.

Technical Abstract: Conserved Herpesviridae protein kinases (CHPK) are conserved among all members of the Herpesviridae. Herpesviruses lacking CHPK propagate in cell culture at varying degrees, depending on the virus and cell culture system. CHPK is dispensable for Marek’s disease herpesvirus (MDV) replication in cell culture and experimental infection in chickens; however, CHPK—particularly its kinase activity—is essential for horizontal transmission in chickens, also known as natural infection. To address the importance of CHPK during natural infection in chickens, we used liquid chromatography-tandem mass spectrometry (LC-MS/MS) based proteomics of samples collected from live chickens. Comparing modification of viral proteins in feather follicle epithelial (FFE) cells infected with wildtype or a CHPK-null virus, we identified the US10 protein (pUS10) as a potential target for CHPK in vivo. When expression of pUS10 was evaluated in cell culture and in FFE skin cells during in vivo infection, pUS10 was severely reduced or abrogated in cells infected with CHPK mutant or CHPK-null viruses, respectively, indicating a potential role for pUS10 in transmission. To test this hypothesis, US10 was deleted from the MDV genome, and the reconstituted virus was tested for replication, horizontal transmission, and disease induction. Our results showed that removal of US10 had no effect on the ability of MDV to transmit in experimentally infected chickens, but disease induction in naturally infected chickens was significantly reduced. These results show CHPK is necessary for pUS10 expression both in cell culture and in the host, and pUS10 is important for disease induction during natural infection.