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Mutual inhibition between Kaposi's sarcoma-associated herpesvirus and Epstein-Barr virus lytic replication initiators in dually-infected primary effusion lymphoma.

Jiang Y, Xu D, Zhao Y, Zhang L - PLoS ONE (2008)

Bottom Line: Both Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV) are members of the human gamma herpesvirus family: each is associated with various human cancers.The majority of AIDS-associated primary effusion lymphoma (PEL) are co-infected with both KSHV and EBV.The leucine heptapeptide repeat (LR) region in K-RTA and leucine zipper region in EBV-Z are involved in the physical interactions of the two molecules.

View Article: PubMed Central - PubMed

Affiliation: Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska, USA.

ABSTRACT

Background: Both Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV) are members of the human gamma herpesvirus family: each is associated with various human cancers. The majority of AIDS-associated primary effusion lymphoma (PEL) are co-infected with both KSHV and EBV. Dually-infected PELs selectively switch from latency to lytic replication of either KSHV or EBV in response to chemical stimuli. KSHV replication and transcription activator (K-RTA) is necessary and sufficient for the switch from KSHV latency to lytic replication, while EBV BZLF1 gene product (EBV-Z) is a critical initiator for induction of EBV lytic replication.

Methodology/principal findings: We show K-RTA and EBV-Z are co-localized and physically interact with each other in dually-infected PELs. K-RTA inhibits the EBV lytic replication by ifying EBV-Z-mediated EBV lytic gene activation. EBV-Z inhibits KSHV lytic gene expression by blocking K-RTA-mediated transactivations. The physical interaction between K-RTA and EBV-Z are required for the mutual inhibition of the two molecules. The leucine heptapeptide repeat (LR) region in K-RTA and leucine zipper region in EBV-Z are involved in the physical interactions of the two molecules. Finally, initiation of KSHV lytic gene expression is correlated with the reduction of EBV lytic gene expression in the same PEL cells.

Conclusions/significance: In this report, how the two viruses interact with each other in dually infected PELs is addressed. Our data may provide a possible mechanism for maintaining viral latency and for selective lytic replication in dually infected PELs, i.e., through mutual inhibition of two critical lytic replication initiators. Our data about putative interactions between EBV and KSHV would be applicable to the majority of AIDS-associated PELs and may be relevant to the pathogenesis of PELs.

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Related in: MedlinePlus

Initiation of KSHV lytic gene expression correlated with the reduction of EBV lytic gene expression.A. TPA induces either EBV or KSHV lytic replication. BC1 (EBV+/KSHV+) cells were treated with TPA at indicated dosages shown on the top. Cell lysates were used for western blot analyses a day later. The same membrane was stripped and reprobed with other antibodies. The identity of proteins is as shown. The relative levels of EA-D expression (EA-D/Tubulin) and EBV-Z (EBV-Z/Tubulin) were obtained by measuring intensity of EA-D, EBV-Z, and Tubulin using ImageJ 1.37v software (NIH), and are shown on the bottom panels. One representative from three independent experiments is shown. B. Kinetics of K-RTA expression in BC1 cells. BC1 cells were treated with TPA (20 ng/ml), or butyrate (3 mM), or both. Total RNA were isolated at indicated time post treatment. The expression of K-RTA and GAPDH RNA was monitored by RPA with K-RTA and GADPH probes simultaneously. Specific protections of K-RTA and GAPDH RNAs are indicated. The relative levels of K-RTA RNA expression (K-RTA/GAPDH) were obtained by measuring intensity of K-RTA and GAPDH using ImageJ 1.37v software (NIH), and are shown on the bottom. One representative from three independent experiments is shown.
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pone-0001569-g006: Initiation of KSHV lytic gene expression correlated with the reduction of EBV lytic gene expression.A. TPA induces either EBV or KSHV lytic replication. BC1 (EBV+/KSHV+) cells were treated with TPA at indicated dosages shown on the top. Cell lysates were used for western blot analyses a day later. The same membrane was stripped and reprobed with other antibodies. The identity of proteins is as shown. The relative levels of EA-D expression (EA-D/Tubulin) and EBV-Z (EBV-Z/Tubulin) were obtained by measuring intensity of EA-D, EBV-Z, and Tubulin using ImageJ 1.37v software (NIH), and are shown on the bottom panels. One representative from three independent experiments is shown. B. Kinetics of K-RTA expression in BC1 cells. BC1 cells were treated with TPA (20 ng/ml), or butyrate (3 mM), or both. Total RNA were isolated at indicated time post treatment. The expression of K-RTA and GAPDH RNA was monitored by RPA with K-RTA and GADPH probes simultaneously. Specific protections of K-RTA and GAPDH RNAs are indicated. The relative levels of K-RTA RNA expression (K-RTA/GAPDH) were obtained by measuring intensity of K-RTA and GAPDH using ImageJ 1.37v software (NIH), and are shown on the bottom. One representative from three independent experiments is shown.

Mentions: BC1 cells were treated with different concentration of TPA, and the lytic gene expression of both EBV and KSHV were analyzed simultaneously. At low level of TPA treatments, EBV lytic gene expression was induced as indicated by the expression of EA-D as well as EBV-Z. However, at higher levels of TPA treatment, EBV lytic gene expression was turned down. Coincidently, the KSHV lytic gene expression was initiated as indicated by the expression of K-RTA and K-8. Thus, TPA could induce either EBV or KSHV lytic gene expression in BC cells depending on the dosages. More importantly, the KSHV lytic gene expression apparently correlated with dampened EBV lytic gene expression. EBV-Z was induced in a dose dependent manner. At TPA 20 ng/ml, EBV-Z was expressed at the highest levels, but the EA-D expression was dropped (Fig 6A; bottom panel). Based on the data in Figures 1 and 2, the expression of K-RTA might block the function of EBV-Z, which reduced the EA-D levels. Furthermore, the excess K-RTA might activate KSHV lytic replication as determined by KSHV K8 expression. It is of note that although different batches of TPA had different dose response curves, the general trend was the same even with TPAs from different companies (data not shown).


Mutual inhibition between Kaposi's sarcoma-associated herpesvirus and Epstein-Barr virus lytic replication initiators in dually-infected primary effusion lymphoma.

Jiang Y, Xu D, Zhao Y, Zhang L - PLoS ONE (2008)

Initiation of KSHV lytic gene expression correlated with the reduction of EBV lytic gene expression.A. TPA induces either EBV or KSHV lytic replication. BC1 (EBV+/KSHV+) cells were treated with TPA at indicated dosages shown on the top. Cell lysates were used for western blot analyses a day later. The same membrane was stripped and reprobed with other antibodies. The identity of proteins is as shown. The relative levels of EA-D expression (EA-D/Tubulin) and EBV-Z (EBV-Z/Tubulin) were obtained by measuring intensity of EA-D, EBV-Z, and Tubulin using ImageJ 1.37v software (NIH), and are shown on the bottom panels. One representative from three independent experiments is shown. B. Kinetics of K-RTA expression in BC1 cells. BC1 cells were treated with TPA (20 ng/ml), or butyrate (3 mM), or both. Total RNA were isolated at indicated time post treatment. The expression of K-RTA and GAPDH RNA was monitored by RPA with K-RTA and GADPH probes simultaneously. Specific protections of K-RTA and GAPDH RNAs are indicated. The relative levels of K-RTA RNA expression (K-RTA/GAPDH) were obtained by measuring intensity of K-RTA and GAPDH using ImageJ 1.37v software (NIH), and are shown on the bottom. One representative from three independent experiments is shown.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2215330&req=5

pone-0001569-g006: Initiation of KSHV lytic gene expression correlated with the reduction of EBV lytic gene expression.A. TPA induces either EBV or KSHV lytic replication. BC1 (EBV+/KSHV+) cells were treated with TPA at indicated dosages shown on the top. Cell lysates were used for western blot analyses a day later. The same membrane was stripped and reprobed with other antibodies. The identity of proteins is as shown. The relative levels of EA-D expression (EA-D/Tubulin) and EBV-Z (EBV-Z/Tubulin) were obtained by measuring intensity of EA-D, EBV-Z, and Tubulin using ImageJ 1.37v software (NIH), and are shown on the bottom panels. One representative from three independent experiments is shown. B. Kinetics of K-RTA expression in BC1 cells. BC1 cells were treated with TPA (20 ng/ml), or butyrate (3 mM), or both. Total RNA were isolated at indicated time post treatment. The expression of K-RTA and GAPDH RNA was monitored by RPA with K-RTA and GADPH probes simultaneously. Specific protections of K-RTA and GAPDH RNAs are indicated. The relative levels of K-RTA RNA expression (K-RTA/GAPDH) were obtained by measuring intensity of K-RTA and GAPDH using ImageJ 1.37v software (NIH), and are shown on the bottom. One representative from three independent experiments is shown.
Mentions: BC1 cells were treated with different concentration of TPA, and the lytic gene expression of both EBV and KSHV were analyzed simultaneously. At low level of TPA treatments, EBV lytic gene expression was induced as indicated by the expression of EA-D as well as EBV-Z. However, at higher levels of TPA treatment, EBV lytic gene expression was turned down. Coincidently, the KSHV lytic gene expression was initiated as indicated by the expression of K-RTA and K-8. Thus, TPA could induce either EBV or KSHV lytic gene expression in BC cells depending on the dosages. More importantly, the KSHV lytic gene expression apparently correlated with dampened EBV lytic gene expression. EBV-Z was induced in a dose dependent manner. At TPA 20 ng/ml, EBV-Z was expressed at the highest levels, but the EA-D expression was dropped (Fig 6A; bottom panel). Based on the data in Figures 1 and 2, the expression of K-RTA might block the function of EBV-Z, which reduced the EA-D levels. Furthermore, the excess K-RTA might activate KSHV lytic replication as determined by KSHV K8 expression. It is of note that although different batches of TPA had different dose response curves, the general trend was the same even with TPAs from different companies (data not shown).

Bottom Line: Both Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV) are members of the human gamma herpesvirus family: each is associated with various human cancers.The majority of AIDS-associated primary effusion lymphoma (PEL) are co-infected with both KSHV and EBV.The leucine heptapeptide repeat (LR) region in K-RTA and leucine zipper region in EBV-Z are involved in the physical interactions of the two molecules.

View Article: PubMed Central - PubMed

Affiliation: Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska, USA.

ABSTRACT

Background: Both Kaposi's sarcoma-associated herpesvirus (KSHV) and Epstein-Barr virus (EBV) are members of the human gamma herpesvirus family: each is associated with various human cancers. The majority of AIDS-associated primary effusion lymphoma (PEL) are co-infected with both KSHV and EBV. Dually-infected PELs selectively switch from latency to lytic replication of either KSHV or EBV in response to chemical stimuli. KSHV replication and transcription activator (K-RTA) is necessary and sufficient for the switch from KSHV latency to lytic replication, while EBV BZLF1 gene product (EBV-Z) is a critical initiator for induction of EBV lytic replication.

Methodology/principal findings: We show K-RTA and EBV-Z are co-localized and physically interact with each other in dually-infected PELs. K-RTA inhibits the EBV lytic replication by ifying EBV-Z-mediated EBV lytic gene activation. EBV-Z inhibits KSHV lytic gene expression by blocking K-RTA-mediated transactivations. The physical interaction between K-RTA and EBV-Z are required for the mutual inhibition of the two molecules. The leucine heptapeptide repeat (LR) region in K-RTA and leucine zipper region in EBV-Z are involved in the physical interactions of the two molecules. Finally, initiation of KSHV lytic gene expression is correlated with the reduction of EBV lytic gene expression in the same PEL cells.

Conclusions/significance: In this report, how the two viruses interact with each other in dually infected PELs is addressed. Our data may provide a possible mechanism for maintaining viral latency and for selective lytic replication in dually infected PELs, i.e., through mutual inhibition of two critical lytic replication initiators. Our data about putative interactions between EBV and KSHV would be applicable to the majority of AIDS-associated PELs and may be relevant to the pathogenesis of PELs.

Show MeSH
Related in: MedlinePlus