Gain of function studies on predicted host receptors for white spot virus

• Published in: Fish & shellfish immunology 2022-12, Vol.131, p.196-205
• Main Authors: Kumar, Gulshan, Gireesh-Babu, P., Rajendran, K.V., Goswami, Mukunda, Chaudhari, Aparna
• Format: Article
• Language: English
• Subjects: Animals; Carrier Proteins - metabolism; Gain of Function Mutation; Host-pathogen interaction; Penaeidae; Shrimp disease; Viral Envelope Proteins - genetics; Viral pathogenesis; Virus Internalization; White spot syndrome virus; White spot syndrome virus 1 - physiology; WSSV
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2022.09.010

Three decades after its first outbreak, the shrimp white spot virus (WSV) is still a global cause of concern due to considerable losses and lack of effective control measures. Several candidate host receptor proteins have been identified, but the pathogenesis is not clearly understood, although the key role of the WSV envelope protein VP28 in virus internalization is established. Here, protein-protein docking is applied to evaluate the interaction of VP28 trimeric extracellular region with four host (Penaeus monodon) receptors reported earlier, Rab7 GTPase (PmRab7), glucose transporter 1 (PmGLUT1), C-type lectin (PmCTL) and calreticulin (PmCRT). The stability of predicted complexes evaluated in terms of binding energy per unit buried surface area ranged from −8.46 to −11.82 cal mol−1/Å2, which is not sufficient for functional interaction. Nevertheless, each of these host proteins was tested by a gain-of-function approach by observing their ability to make a fish cell line permissive to the shrimp WSV. Full-length expression constructs of the four receptors were transfected into SSN1 snakehead fish cells that are non-permissive to WSV. Transfected SSN1 cells and WSV permissive insect Sf9 cells were challenged with purified WSV. After 24 h, the presence of receptor transcripts was confirmed in the treated SSN1 cells, and not in the non-transfected SSN1 cells. Further, vp28 transcript was detected in Sf9 cells, but not in any of the treated SSN1 cells, indicating that none of the receptors were singly sufficient to make SSN1 cells permissive to WSV, even though PmRab7 was a strong candidate that alone showed >85% protection in virus neutralization experiments. For the other 3 candidates, previous reports predicted the involvement of co-receptors, which is confirmed here by their inability to act singly. •Four host receptors predicted to mediate WSV internalization do not individually interact with VP28 in docking studies.•Gain of function studies in non-permissive SSN1 cells show the inability of any single host receptor to internalize WSV.•Results indicate the involvement of more than one host receptors in mediating WSV entry.