EBNA-2-Deleted Epstein-Barr Virus from P3HR-1 Can Infect Rabbits with Lower Efficiency than Prototype Epstein-Barr Virus from B95-8

Abstract

Objectives: To clarify characteristics on rabbit in vivo infection with type 2 EBV nuclear antigen (EBNA-2)-deleted Epstein-Barr virus (P3HR-1-EBV) and compare infectious efficacy of P3HR-1-EBV with previously reported prototype type 1 EBV from B95-8. Methods: Twelve Japanese White rabbits were inoculated with P3HR-1-EBV via intranasal or intravenous routes and autopsied on day 70–84. Results: In only 2 of 12 P3HR-1-EBV-inoculated rabbits, EBV-DNA was detected in peripheral blood mononuclear cells (PBMCs). BamHI M rightward reading frame (BMRF)-1, EBNA-1 and BamHI Z leftward reading frame (BZLF)-1-mRNA were intermittently expressed in PBMCs. In 1 infected rabbit with continuous detection of EBV-DNA in PBMCs, many EBER-1-positive lymphocytes were observed in germinal centers and/or marginal zones in some follicles of the appendix, and for the first time a lymphocyte with EBER-1 expression infiltrating in the squamous cell layer of the tonsils was found. The other rabbit with a transient detection of EBV-DNA in PBMCs had no EBER-1-positive lymphocytes in the tissues examined. Few EBER-1-positive lymphocytes were detected in some rabbits without detection of EBV-DNA in PBMCs. Conclusions: P3HR-1-EBV showed less efficient infection in rabbits than EBV from the B95-8 cell line. However, a P3HR-1-EBV-inoculated animal model is meaningful because this is the first study of EBNA-2 function on in vivo EBV infection and it demonstrated the in vivo infectivity with lytic-type infection by EBNA-2-deleted EBV.

Assessing the Efficacy of VLP-Based Vaccine against Epstein-Barr Virus Using a Rabbit Model

“…Although B-95-8 is a very commonly used source of EBV, it is important to assess if the rabbits are equally susceptible to infection with other strains of the virus. A previous study reported that rabbits were susceptible to P3HR1 stain [ 65 ]. However, this strain lacks EBNA2 and is, therefore, not a bona fide representative of wild-type virus infecting humans.…”

Epstein-Barr Virus (HHV-4) Inoculation to Rabbits by Intranasal and Oral Routes Results in Subacute and/or Persistent Infection Dissimilar to Human Disease

“…The EBV DNA persistence in the spleen as revealed by the presence of EBER-positive lymphocytes, LMP1, EBNA2 and ZEBRA mRNAs occurred in a proportion of rabbits resulting from intravenous inoculation with a very high virus load [13]. It seems that both the route of virus administration as well as the source of the inoculated virus might be essential for its further spread and for the efficiency of elimination of the persisting (or latent) virus genome [38,39,40]. Summing up, the EBV DNA in our rabbits was present in a smaller proportion of B lymphocytes along with simultaneous expression of LMP1 antigen and the absence of EBNA-1 antibody.…”

EBV and Lymphomagenesis

“…These results are consistent with previous experiments showing that EBNA2 is essential in B-cell transformation [ 47 ]. However, in vivo experiments indicate that EBNA2 deletion does not preclude the establishment of infection [ 48 ] or development of cancer [ 49 ]. Notably, EBNA2 expression is highly efficient; experiments have shown that a single detectable EBV genome is sufficient to drive EBNA2 expression [ 50 ].…”