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A Recombinant Rhesus Monkey Rhadinovirus Deleted of Glycoprotein L Establishes Persistent Infection of Rhesus Macaques and Elicits Conventional T Cell Responses
ISSN
0022-538X
Date Issued
2020
Author(s)
Bischof, Georg F.
Großkopf, Anna K.
Shin, Young C.
Domingues, Aline
Gonzalez-Nieto, Lucas
Rakasz, Eva G.
Watkins, David I.
Ensser, Armin
Martins, Mauricio A.
Editor(s)
Longnecker, Richard M.
DOI
10.1128/JVI.01093-19
Abstract
Kaposi’s sarcoma-associated herpesvirus (KSHV) is associated with a substantial disease burden in sub-Saharan Africa, often in the context of human immunodeficiency virus (HIV) infection. The related rhesus monkey rhadinovirus (RRV) has shown potential as a vector to immunize monkeys with antigens from simian immunodeficiency virus (SIV), the macaque model for HIV. KSHV and RRV engage cellular receptors from the Eph family via the viral gH/gL glycoprotein complex. We have now generated a recombinant RRV that expresses the SIV Gag antigen and does not express gL. This recombinant RRV was infectious by the intravenous route, established persistent infection in the B cell compartment, and elicited strong immune responses to the SIV Gag antigen. These results argue against a role for gL and Eph family receptors in B cell infection by RRV
in vivo
and have implications for the development of a live-attenuated KSHV vaccine or vaccine vector.
in vivo
and have implications for the development of a live-attenuated KSHV vaccine or vaccine vector.
ABSTRACT
A replication-competent, recombinant strain of rhesus monkey rhadinovirus (RRV) expressing the Gag protein of SIVmac239 was constructed in the context of a glycoprotein L (gL) deletion mutation. Deletion of gL detargets the virus from Eph family receptors. The ability of this gL-minus Gag recombinant RRV to infect, persist, and elicit immune responses was evaluated after intravenous inoculation of two
Mamu-A*01
+
RRV-naive rhesus monkeys. Both monkeys responded with an anti-RRV antibody response, and quantitation of RRV DNA in peripheral blood mononuclear cells (PBMC) by real-time PCR revealed levels similar to those in monkeys infected with recombinant gL
+
RRV. Comparison of RRV DNA levels in sorted CD3
+
versus CD20
+
versus CD14
+
PBMC subpopulations indicated infection of the CD20
+
subpopulation by the gL-minus RRV. This contrasts with results obtained with transformed B cell lines
in vitro
, in which deletion of gL resulted in markedly reduced infectivity. Over a period of 20 weeks, Gag-specific CD8
+
T cell responses were documented by major histocompatibility complex class I (MHC-I) tetramer staining. Vaccine-induced CD8
+
T cell responses, which were predominantly directed against the Mamu-A*01-restricted Gag
181-189
CM9 epitope, could be inhibited by blockade of MHC-I presentation. Our results indicate that gL and the interaction with Eph family receptors are dispensable for the colonization of the B cell compartment following high-dose infection by the intravenous route, which suggests the existence of alternative receptors. Further, gL-minus RRV elicits cellular immune responses that are predominantly canonical in nature.
IMPORTANCE
Kaposi’s sarcoma-associated herpesvirus (KSHV) is associated with a substantial disease burden in sub-Saharan Africa, often in the context of human immunodeficiency virus (HIV) infection. The related rhesus monkey rhadinovirus (RRV) has shown potential as a vector to immunize monkeys with antigens from simian immunodeficiency virus (SIV), the macaque model for HIV. KSHV and RRV engage cellular receptors from the Eph family via the viral gH/gL glycoprotein complex. We have now generated a recombinant RRV that expresses the SIV Gag antigen and does not express gL. This recombinant RRV was infectious by the intravenous route, established persistent infection in the B cell compartment, and elicited strong immune responses to the SIV Gag antigen. These results argue against a role for gL and Eph family receptors in B cell infection by RRV
in vivo
and have implications for the development of a live-attenuated KSHV vaccine or vaccine vector.
A replication-competent, recombinant strain of rhesus monkey rhadinovirus (RRV) expressing the Gag protein of SIVmac239 was constructed in the context of a glycoprotein L (gL) deletion mutation. Deletion of gL detargets the virus from Eph family receptors. The ability of this gL-minus Gag recombinant RRV to infect, persist, and elicit immune responses was evaluated after intravenous inoculation of two
Mamu-A*01
+
RRV-naive rhesus monkeys. Both monkeys responded with an anti-RRV antibody response, and quantitation of RRV DNA in peripheral blood mononuclear cells (PBMC) by real-time PCR revealed levels similar to those in monkeys infected with recombinant gL
+
RRV. Comparison of RRV DNA levels in sorted CD3
+
versus CD20
+
versus CD14
+
PBMC subpopulations indicated infection of the CD20
+
subpopulation by the gL-minus RRV. This contrasts with results obtained with transformed B cell lines
in vitro
, in which deletion of gL resulted in markedly reduced infectivity. Over a period of 20 weeks, Gag-specific CD8
+
T cell responses were documented by major histocompatibility complex class I (MHC-I) tetramer staining. Vaccine-induced CD8
+
T cell responses, which were predominantly directed against the Mamu-A*01-restricted Gag
181-189
CM9 epitope, could be inhibited by blockade of MHC-I presentation. Our results indicate that gL and the interaction with Eph family receptors are dispensable for the colonization of the B cell compartment following high-dose infection by the intravenous route, which suggests the existence of alternative receptors. Further, gL-minus RRV elicits cellular immune responses that are predominantly canonical in nature.
IMPORTANCE
Kaposi’s sarcoma-associated herpesvirus (KSHV) is associated with a substantial disease burden in sub-Saharan Africa, often in the context of human immunodeficiency virus (HIV) infection. The related rhesus monkey rhadinovirus (RRV) has shown potential as a vector to immunize monkeys with antigens from simian immunodeficiency virus (SIV), the macaque model for HIV. KSHV and RRV engage cellular receptors from the Eph family via the viral gH/gL glycoprotein complex. We have now generated a recombinant RRV that expresses the SIV Gag antigen and does not express gL. This recombinant RRV was infectious by the intravenous route, established persistent infection in the B cell compartment, and elicited strong immune responses to the SIV Gag antigen. These results argue against a role for gL and Eph family receptors in B cell infection by RRV
in vivo
and have implications for the development of a live-attenuated KSHV vaccine or vaccine vector.
