Project Title
The role of E4 11k in inhibiting RIG-I activation and preventing a type 1 interferon response
Faculty Mentor(s) Name(s)
Kasey Karen
Abstract
Adenovirus is a double-stranded DNA virus whose goal is to turn cells into replication machines without the host recognizing that it has been infected. To do this, adenovirus has genes that produce proteins that can restructure certain pathways in the host cell. The adenovirus gene, E4 ORF3, which encodes the protein, E4 11k, is one component that contributes to these changes. This viral protein is able to redistribute host cell proteins, such as the p body protein, DEAD-box helicase 6 (Ddx6), through a direct interaction. The host cell has defense mechanisms in place to recognize that it has been infected. Retinoic-acid inducible gene I (RIG-I) is a viral RNA sensor that can induce a type I interferon response, which includes using interferon beta (IFNB). To mitigate the effect of this recognition process, other viruses have been shown to express proteins that interact with Ddx6, leading to the inhibition of RIG-I-activation of interferon beta. We hypothesize that viral protein E4 11K is able to interfere with the interaction between RIG-I and Ddx6, which suppresses the type I interferon response during the earlier phase of infection. The RIG-I activation of the type I interferon response will be observed by quantitating the mRNA levels of RIG-I and IFNB via qRT-PCR. We compared wild-type adenovirus with an E4-deleted virus that lacks E4 ORF3 along with other genes in the E4 region at a late time during infection. Both the RIG-I and IFNB levels increased by 52 hours post-infection with the E4-deleted virus. This indicates that one of the proteins encoded in the E4 region may be responsible for inhibiting the type I interferon response late during an infection. Ongoing studies will address the role of E4 11k specifically using additional deletion mutants and a virus that expresses E4 11k alone.
The role of E4 11k in inhibiting RIG-I activation and preventing a type 1 interferon response
Adenovirus is a double-stranded DNA virus whose goal is to turn cells into replication machines without the host recognizing that it has been infected. To do this, adenovirus has genes that produce proteins that can restructure certain pathways in the host cell. The adenovirus gene, E4 ORF3, which encodes the protein, E4 11k, is one component that contributes to these changes. This viral protein is able to redistribute host cell proteins, such as the p body protein, DEAD-box helicase 6 (Ddx6), through a direct interaction. The host cell has defense mechanisms in place to recognize that it has been infected. Retinoic-acid inducible gene I (RIG-I) is a viral RNA sensor that can induce a type I interferon response, which includes using interferon beta (IFNB). To mitigate the effect of this recognition process, other viruses have been shown to express proteins that interact with Ddx6, leading to the inhibition of RIG-I-activation of interferon beta. We hypothesize that viral protein E4 11K is able to interfere with the interaction between RIG-I and Ddx6, which suppresses the type I interferon response during the earlier phase of infection. The RIG-I activation of the type I interferon response will be observed by quantitating the mRNA levels of RIG-I and IFNB via qRT-PCR. We compared wild-type adenovirus with an E4-deleted virus that lacks E4 ORF3 along with other genes in the E4 region at a late time during infection. Both the RIG-I and IFNB levels increased by 52 hours post-infection with the E4-deleted virus. This indicates that one of the proteins encoded in the E4 region may be responsible for inhibiting the type I interferon response late during an infection. Ongoing studies will address the role of E4 11k specifically using additional deletion mutants and a virus that expresses E4 11k alone.