Host-Specific Restriction of Avian Influenza Virus Caused by Differential Dynamics of ANP32 Family Members

Abstract

Background Influenza viruses must utilize host factors to complete their lifecycle. Species-specific differences in host factors between birds and mammals mean that avian influenza viruses (AIVs) replicate well in avian hosts but not in human hosts. Acidic nuclear phosphoprotein 32 family member A (ANP32A) has been identified as the host restriction factor for the viral polymerase (vPol) activity of AIVs. The ANP32A belongs to the conserved ANP32 family, the functional roles of which during viral replication remain unclear. Methods In this study, we targeted chicken ANP32A using clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9-mediated genome editing to examine the functional roles of ANP32A and other members of the ANP32 family. Results We showed that chicken ANP32A only, not ANP32B and ANP32E, plays a pivotal role in supporting vPol activity of AIVs. Furthermore, we found that the human ANP32C, ANP32D, and ANP32E have suppressive effects on vPol activity in contrast to human ANP32A and ANP32B. Conclusions Chicken and human ANP32 family members had different effects on vPol activity, suggesting that species-specific vPol activity of AIVs could be caused by the differential functions and overall competency of ANP32 family members.

Swine ANP32A Supports Avian Influenza Virus Polymerase

“…Initially, we tested a panel of polymerases derived from human, canine, equine and bat influenza viruses. In contrast to chicken ANP32B, which does not support influenza virus polymerase activity (15,19,20), chicken ANP32A and all mammalian ANP32A and ANP32B on October 2, 2020 by guest http://jvi.asm.org/ Downloaded from proteins supported activity of the mammalian-origin viral polymerases to varying degrees ( Fig. 1a).…”

“…In mice, only ANP32B can support influenza A polymerase activity (18,19). Neither avian nor mammalian ANP32E proteins have been shown to support influenza polymerase activity (18)(19)(20).…”

“…In humans, two paralogues -ANP32A and ANP32B -are essential but redundant influenza polymerase cofactors (18,19). In birds, only a single family member -ANP32A -supports influenza virus polymerase activity, as avian ANP32B proteins are not orthologous to mammalian ANP32B (15,19,20). In mice, only ANP32B can support influenza A polymerase activity (18,19).…”

Precise Genome Editing in Poultry and Its Application to Industries

“…Based on these preliminary studies, genome-edited chickens were developed that harbored a precise deletion in tryptophan at residue 38 (W38) in chNHE1 and were resistant to ALV-J infection [ 7 ]. In the case of influenza A virus (IAV), host factor ANP32A plays a critical role in supporting the vPol activity of IAV [ 81 , 82 , 83 ]. In chicken ANP32A, an additional 33 amino acids are present between the leucine-rich repeats and C-terminal acidic region, and when these 33 amino acids are deleted, IAV replication in avian cells is significantly disrupted [ 81 ].…”

“…In chicken ANP32A, an additional 33 amino acids are present between the leucine-rich repeats and C-terminal acidic region, and when these 33 amino acids are deleted, IAV replication in avian cells is significantly disrupted [ 81 ]. It has been speculated that if these 33 amino acids could be precisely deleted by genome editing, an IAV-resistant chicken could be produced [ 81 , 82 , 83 ]. These results imply that when host factors are identified as critical for viral entry or replication, we can successfully develop disease-resistant lines by genome editing.…”