Human T cell leukemia virus type 2 (HTLV-2) Tax2 has a dominant activity over HTLV-1 Tax1 to immortalize human CD4+ T cells

While human T cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T cell leukemia, a close relative, HTLV-2, is not associated with any leukemia. HTLV-1 and HTLV-2 encode the Tax1 and Tax2 proteins, respectively, which are essential for the immortalization of human T cells by the respective viruses, thereby causing persistent infection. In this study, we compared Tax1 and Tax2 with respect to their immortalization activity in human T cells. Lentivirus-mediated transduction of the tax2 gene into human peripheral blood mononuclear cells stimulated with phytohemagglutinin and interleukin-2 in 96-well plates induced outgrowing T cells in most wells, but the cells infected with the control viruses died within 3 weeks. Surprisingly, the number of outgrowing cells induced by Tax2 was much higher than that induced by Tax1, and the appearance of outgrowing cells by Tax2 was earlier than that induced by Tax1. Nevertheless, both Tax2 and Tax1 preferentially immortalized CD4(+) T cells, but not CD8(+) T cells. Our study showed that HTLV-2 Tax2 can immortalize human CD4(+) T cells, and the activity is much higher than that of Tax1. The distinct T cell immortalization activities of Tax2 and Tax1 might therefore play a role in the different pathogeneses observed for these two viruses.

Activation of mTOR by human T-cell leukemia virus type 1 Tax is important for the transformation of mouse T cells to interleukin-2-independent growth

Human T-cell leukemia virus type 1 (HTLV-1) is a causative agent of adult T-cell leukemia, and it immortalizes and transforms human T cells in both an interleukin (IL)-2-dependent and -independent manner. HTLV-1 encodes Tax, which plays crucial roles in HTLV-1-mediated immortalization and transformation of human T cells. A previous study showed that Tax can transform a mouse T-cell line, CTLL-2, from having IL-2-dependent growth to IL-2-independent growth. Given that the Akt/mTOR pathway is essential for IL-2-induced cell growth in T cells, we examined whether the Akt/mTOR pathway is involved in Tax-induced transformation to IL-2-independent growth. The stable and transient expression of Tax in CTLL-2 induced the phosphorylation of p70S6 kinase and ribosomal protein S6, downstream targets of the mTOR kinase, whereas that of Akt was only minimally induced. Studies with Tax mutants indicated that the activation of mTOR by Tax was correlated with the transformation of CTLL-2 cells to IL-2-independent growth. Rapamycin, an inhibitor of mTOR kinase, reduced the growth of Tax-transformed CTLL-2 cells. Moreover, the transduction of a constitutively active form of Akt in the CTLL-2 cells also induced IL-2-independent growth. Like CTLL-2/Tax, constitutive phosphorylation of p70S6 kinase was detected in the absence of IL-2 in all of the HTLV-1-infected human T-cell lines. These results suggest that Tax activates the mTOR pathway in T cells, and that this activation plays a crucial role in the growth of HTLV-1-infected T cells when a limited amount of IL-2 is available.

The PDZ domain binding motif (PBM) of human T-cell leukemia virus type 1 Tax can be substituted by heterologous PBMs from viral oncoproteins during T-cell transformation

Several tumor viruses, such as human T-cell leukemia virus (HTLV), human papilloma virus (HPV), human adenovirus, have high-oncogenic and low-oncogenic subtypes, and such subtype-specific oncogenesis is associated with the PDZ-domain binding motif (PBM) in their transforming proteins. HTLV-1, the causative agent of adult T-cell leukemia, encodes Tax1 with PBM as a transforming protein. The Tax1 PBM was substituted with those from other oncoviruses, and the transforming activity was examined. Tax1 mutants with PBM from either HPV-16 E6 or adenovirus type 9 E4ORF1 are fully active in the transformation of a mouse T-cell line from interleukin-2-dependent growth into independent growth. Interestingly, one such Tax1 PBM mutant had an extra amino acid insertion derived from E6 between PBM and the rest of Tax1, thus suggesting that the amino acid sequences of the peptides between PBM and the rest of Tax1 and the numbers only slightly affect the function of PBM in the transformation. Tax1 and Tax1 PBM mutants interacted with tumor suppressors Dlg1 and Scribble with PDZ-domains. Unlike E6, Tax1 PBM mutants as well as Tax1 did not or minimally induced the degradations of Dlg1 and Scribble, but instead induced their subcellular translocation from the detergent-soluble fraction into the insoluble fraction, thus suggesting that the inactivation mechanism of these tumor suppressor proteins is distinct. The present results suggest that PBMs of high-risk oncoviruses have a common function(s) required for these three tumor viruses to transform cells, which is likely associated with the subtype-specific oncogenesis of these tumor viruses.

Identification of a novel motif responsible for the distinctive transforming activity of human T-cell leukemia virus (HTLV) type 1 Tax1 protein from HTLV-2 Tax2

Background

Human T-cell leukemia virus type 1 (HTLV-1) is a causative agent of adult T-cell leukemia (ATL), whereas its relative HTLV-2 is not associated with any malignancies including ATL. HTLV-1 Tax1 transformed a T-cell line from interleukin (IL)-2-dependent growth to IL-2-independent growth, with an activity that was much more potent in comparison to HTLV-2 Tax2. This distinction was mediated by at least two Tax1 specific functions, an interaction with host cellular factors through the PDZ domain binding motif (PBM) and the activation of NF-kappaB2 (NF-κB2)/p100.

Results

Using a series of Tax1 chimeric proteins with Tax2, we found that amino acids 225-232 of Tax1, the Tax1(225-232) region, was essential for the activation of NF-κB2 as well as for the high transforming activity. The strict amino acid conservation of Tax1(225-232) among HTLV-1 and simian T-cell leukemia virus type 1 (STLV-1), but not HTLV-2 and STLV-2, indicates that function(s) through the Tax1(225-232) region are biologically significant. Interestingly, another HTLV-1 relative, HTLV-3, has a PBM, but does not conserve the Tax1(225-232) motif in Tax3, thus indicating that these two motifs classify the three HTLVs into the separate groups.

Conclusion

These results suggest that the combinatory functions through Tax1(225-232) and PBM play crucial roles in the distinct biological properties of the three HTLVs, perhaps also including their pathogenesis.

Human T-cell leukemia virus type 1 Tax induces an aberrant clustering of the tumor suppressor Scribble through the PDZ domain-binding motif dependent and independent interaction

Human T-cell leukemia virus type 1 (HTLV-1) is a causative agent of adult T-cell leukemia. HTLV-1 Tax1 transforming protein interacts with several PDZ domain-containing proteins, and the interaction is associated with the transforming activities of Tax1 as well as persistent HTLV-1 infection. In this study, we show that Tax1 interacts with the tumor suppressor Scribble containing PDZ domains. Unlike other Tax1-interacting PDZ domain proteins, the PDZ domain-binding motif (PBM) of Tax1 was not required for the interaction with transiently expressed Scribble in 293T cells, but it was essential for the interaction with endogenous Scribble. Endogenous Scribble in 293T cells was primarily localized at the plasma membrane and colocalized with Tax1 but not Tax1C lacking PBM, whereas transiently expressed Scribble was localized in the cytoplasm and colocalized with Tax1C as well as Tax1, thus suggesting that Tax1 is recruited to the site of endogenous Scribble, such as the plasma membrane, in a PBM-dependent manner, and thereafter it interacts with Scribble in a PBM-independent and PBM-dependent manner. Endogenous Scribble was diffusely localized at the plasma membrane of HTLV-1-uninfected T-cell lines, whereas it colocalized with Tax1 as small and large aggregate at the plasma membranes. These results suggest that Tax1 through two binding sites induce aberrant clustering of Scribble, thereby altering the functions in HTLV-1-infected cells, which may thus play a role in persistent HTLV-1 infection and the pathogenesis.

Cooperation of NF-kappaB2/p100 activation and the PDZ domain binding motif signal in human T-cell leukemia virus type 1 (HTLV-1) Tax1 but not HTLV-2 Tax2 is crucial for interleukin-2-independent growth transformation of a T-cell line

Human T-cell leukemia virus type 1 (HTLV-1) but not HTLV-2 is associated with adult T-cell leukemia, and the distinct pathogenicity of these two closely related viruses is thought to stem from the distinct biological functions of the respective transforming proteins, HTLV-1 Tax1 and HTLV-2 Tax2. In this study, we demonstrate that Tax1 but not Tax2 interacts with NF-kappaB2/p100 and activates it by inducing the cleavage of p100 into the active transcription factor p52. Using RNA interference methods, we further show that NF-kappaB2/p100 is required for the transformation induced by Tax1, as determined by the ability to convert a T-cell line (CTLL-2) from interleukin-2 (IL-2)-dependent to -independent growth. While Tax2 shows a reduced transforming activity relative to Tax1, Tax2 fused with a PDZ domain binding motif (PBM) present only in Tax1 shows transforming activity equivalent to that of Tax1 in CTLL-2 cells expressing an inducer of p52 processing. These results reveal that the activation of NF-kappaB2/p100 plays a crucial role in the Tax1-mediated transformation of T cells and that NF-kappaB2/p100 activation and PBM function are both responsible for the augmented transforming activity of Tax1 relative to Tax2, thus suggesting that these Tax1-specific functions play crucial roles in HTLV-1 leukemogenesis.

Isolation and characterization of novel human parechovirus from clinical samples

Identification of HPeV-6 will advance HPeV diagnosis and epidemiology.

Using Vero cells, we isolated a virus (NII561-2000) from a cerebrospinal fluid specimen of a 1-year-old girl with Reye syndrome. The determined amino acid sequence of the virus indicated that the isolate was a human parechovirus (HPeV), a member of Picornaviridae. Neutralization test showed that the NII561-2000 virus had distinct antigenicity to HPeV-1, HPeV-2, and HPeV-3, and that the sequence was distinct from these types as well as from HPeV-4 and HPeV-5. Thus, we propose the virus (NII561-2000) as the prototype of HPeV-6. We isolated 10 NII561-2000–related viruses, 14 HPeV-1, 16 HPeV-3, and 1 HPeV-4 of 41 HPeVs from various clinical samples collected in Niigata, Japan. Clinical symptoms of the persons infected with the NII561-2000–related viruses were infectious gastroenteritis, rash, upper respiratory tract infection, and paralysis, in addition to Reye syndrome in the 1-year-old girl.

Performance and quality assurance of genotypic drug-resistance testing for human immunodeficiency virus type 1 in Japan

Highly active antiretroviral therapy (HAART) can suppress human immunodeficiency virus type 1 (HIV-1) replication and plasma HIV-1 to below detectable levels. However, HAART becomes ineffective when drug-resistant viruses emerge during HAART. Monitoring drug-resistance mutations in viruses is necessary for selecting new drugs or therapies effective at inhibiting such HIV-1 variants. Most laboratories in Japan perform the tests using in-house protocols. However, the quality of these tests has never been assessed. Our study assessing the accuracy and reliability of HIV-1 genotypic drug-resistance testing in 15 laboratories in Japan revealed that the quality was very high (97.3% accurate). The errors, though rare, were caused by human errors, poor electropherograms, and the use of inadequate primers. Here, we propose troubleshooting procedures to improve testing accuracy and reliability in Japan.

Human T-cell leukemia virus type 2 Tax protein induces interleukin 2-independent growth in a T-cell line

Background:

While human T-cell leukemia virus type 1 (HTLV-1) is a causative agent of adult T-cell leukemia, HTLV type 2 (HTLV-2) is not associated with this malignancy. Accumulating evidence suggests that Tax, a transforming protein of HTLV-1 or HTLV-2, plays a crucial role in the distinctive pathogenesis of these two infections. We herein examined whether Tax2 by itself has a growth promoting activity in a mouse T-cell line CTLL-2, and compared the activity with that of Tax1.

Results:

We found that Tax2 converts the cell growth of CTLL-2 from an interleukin(IL)-2-dependent growth into an independent one. Cyclosporine A, an inhibitor of transcription factor NFAT, inhibited the growth of two out of four Tax2-transformed CTLL-2 cells, but it had little effect on two Tax1-transformed cells. While the HTLV-2-transformed human T-cell lines produce a significant amount of IL-2, Tax2-transformed CTLL-2 cells only produced a minimal amount of IL-2. These results thus suggest that NFAT-inducible gene(s) other than IL-2 play a role in the cell growth of Tax2-transformed CTLL-2 cells.

Conclusion:

These results show that HTLV-2 Tax2 by itself has a growth promoting activity toward a T-cell line CTLL-2, and the CTLL-2 assay used in this study may therefore be a useful tool for comparing the activity of Tax2 with that of Tax1 in T-cells, thereby elucidating the mechanism of HTLV-1 specific leukemogenesis.

A novel KRAB-Zinc finger protein interacts with latency-associated nuclear antigen of Kaposi's sarcoma-associated herpesvirus and activates transcription via terminal repeat sequences

Kaposi's sarcoma-associated herpesvirus (KSHV) establishes latent infection in various cells in vitro as well as KSHV-associated tumor cells in vivo. The latency-associated nuclear antigen (LANA) of KSHV is one of a small number of genes expressed in the latent phase of KSHV infection. This antigen is crucial for establishment of the latent infection, such as replication of KSHV genomic DNA and maintenance of infection via direct interaction with terminal repeats (TRs) in the viral genome. Using a yeast two-hybrid screening method, we isolated a novel LANA-interacting protein (designated as KZLP; KRAB Zinc finger LANA interacting Protein) from a human peripheral leukocyte cDNA library. KZLP encodes a KRAB domain and 12 Kruppel-type zinc fingers. Reverse transcription polymerase chain reaction showed that KZLP was expressed ubiquitously in various cell lines including those infected with KSHV. A luciferase assay showed that KZLP could activate the KSHV open reading frame K1 promoter containing TRs in 293T cells, and that such activation required multiple TR sequences. In contrast, LANA repressed the activity of the K1 promoter through TRs, and again this repression required multiple TR units. Moreover, LANA almost completely abrogated the KZLP-mediated transcriptional activation. Our results suggest that KZLP and LANA regulate gene expression through TRs in the KSHV viral genome, including the K1 gene in latent KSHV-infected cells.

Inactivation of tumor suppressor Dlg1 augments transformation of a T-cell line induced by human T-cell leukemia virus type 1 Tax protein

Background

The interaction of human T-cell leukemia virus type 1 (HTLV-1) Tax1 protein with the tumor suppressor Dlg1 is correlated with cellular transformation.

Results

Here, we show that Dlg1 knockdown by RNA interference increases the ability of Tax1 to transform a mouse T-cell line (CTLL-2), as measured interleukin (IL)-2-independent growth. A Tax1 mutant defective for the Dlg1 interaction showed reduced transformation of CTLL-2 compared to wild type Tax1, but the transformation was minimally affected by Dlg1 reduction. The few Tax1ΔC-transduced CTLL-2 cells that became transformed expressed less Dlg1 than parental cells, suggesting that Dlg1-low cells were selectively transformed by Tax1ΔC. Moreover, all human T-cell lines immortalized by HTLV-1, including the recombinant HTLV-1-containing Tax1ΔC, expressed less Dlg1 than control T-cell lines.

Conclusion

These results suggest that inactivation of Dlg1 augments Tax1-mediated transformation of CTLL-2, and PDZ protein(s) other than Dlg1 are critically involved in the transformation.

Positive symptoms and duration of illness predict functional laterality and attention modulation in schizophrenia

OBJECTIVE

Dichotic listening (DL) performance in schizophrenia, reflecting hemispheric asymmetry and the functional integrity of the left temporal lobe, can vary with clinical characteristics. Previous studies have not taken the co-linearity of clinical variables into account. The aim of the present study was to evaluate the roles of positive symptoms and duration of illness in DL through Structural Equation Modeling (SEM), thus allowing for complex relationships between the variables.

METHOD

We pooled patients from four previous DL studies to create a heterogeneous group of 129 schizophrenic patients, all tested with a consonant-vowel syllables DL procedure that included attentional instructions.

RESULTS

A model where positive symptoms predicted a laterality component and duration of illness predicted an attention component in DL was confirmed.

CONCLUSION

Positive symptoms predicted reduced functional laterality, suggesting involvement of left temporal lobe language processing. Duration of illness predicted impaired attention modulation, possibly reflecting the involvement of frontotemporal networks.

Aberrant activation of the interleukin-2 autocrine loop through the nuclear factor of activated T cells by nonleukemogenic human T-cell leukemia virus type 2 but not by leukemogenic type 1 virus

Human T-cell leukemia virus type 1 (HTLV-1) but not HTLV-2 is associated with adult T-cell leukemia. We found that HTLV-2 Tax2 protein stimulated reporter gene expression regulated by the interleukin (IL)-2 promoter through the nuclear factor of activated T cells (NFAT) in a human T-cell line (Jurkat). However, the activity of HTLV-1 Tax1 was minimal in this system. T-cell lines immortalized by HTLV-2 but not HTLV-1 constitutively exhibited activated NFAT in the nucleus and constitutively expressed IL-2 mRNA. Cyclosporine A, an inhibitor of NFAT activation, abrogated the induction of IL-2 mRNA in HTLV-2-immortalized T-cell lines and concomitantly inhibited cell growth. This growth inhibition was rescued by the addition of IL-2 to the culture. Furthermore, anti-IL-2 receptor antibodies significantly reduced the proliferation of HTLV-2-infected T-cell lines but not that of HTLV-1-infected cells. Our results suggest that Tax2 activates an IL-2 autocrine loop mediated through NFAT that supports the growth of HTLV-2-infected cells under low-IL-2 conditions. This mechanism would be especially important in vivo, where this autocrine mechanism establishes a nonleukemogenic life-long HTLV-2 infection. The results also suggest that differences in long-term cytokine production between HTLV-1 and HTLV-2 infection are another factor for the differences in pathogenesis.

PDZ domain-binding motif of human T-cell leukemia virus type 1 Tax oncoprotein is essential for the interleukin 2 independent growth induction of a T-cell line

Background

Human T-cell leukemia virus type 1 (HTLV-1) is the etiologic agent of adult T-cell leukemia (ATL), whereas HTLV type 2 (HTLV-2), is not associated with ATL or any other leukemia. HTLV-1 encodes the transforming gene tax1, whose expression in an interleukin (IL)-2-dependent T-cell line (CTLL-2) induces IL-2-independent growth.

Results

In this study, we demonstrated that IL-2-independent growth induction by Tax1 was abrogated by mutations of the PDZ domain-binding motif (PBM) at the Tax1 C-terminus. HTLV-2 Tax2, which shares 75% amino acid identity with Tax1 but does not have a PBM, was not able to induce IL-2-independent growth of CTLL-2.

Conclusion

Our results suggest that Tax1, through interaction with PDZ domain protein(s) induces IL-2-independent growth, which may be a factor in multi-step leukemogenesis caused by HTLV-1.

Elevated expression of CD30 in adult T-cell leukemia cell lines: possible role in constitutive NF-kappaB activation

Background

Human T-cell leukemia virus type 1 (HTLV-1) is associated with the development of adult T-cell leukemia (ATL). HTLV-1 encoded Tax1 oncoprotein activates the transcription of genes involved in cell growth and anti-apoptosis through the NF-κB pathway, and is thought to play a critical role in the pathogenesis of ATL. While Tax1 expression is usually lost or minimal in ATL cells, these cells still show high constitutive NF-κB activity, indicating that genetic or epigenetic changes in ATL cells induce activation independent of Tax1. The aim of this study was to identify the molecules responsible for the constitutive activation of NF-κB in ATL cells using a retroviral functional cloning strategy.

Results

Using enhanced green fluorescent protein (EGFP) expression and blasticidin-resistance as selection markers, several retroviral cDNA clones exhibiting constitutive NF-κB activity in Rat-1 cells, including full-length CD30, were obtained from an ATL cell line. Exogenous stable expression of CD30 in Rat-1 cells constitutively activated NF-κB. Elevated expression of CD30 was identified in all ATL lines examined, and primary ATL cells from a small number of patients (8 out of 66 cases).

Conclusion

Elevated CD30 expression is considered one of the causes of constitutive NF-κB activation in ATL cells, and may be involved in ATL development.

Visualization of a Functional KSHV Episome-Maintenance Protein LANA in Living Cells

The latency-associated nuclear antigen (LANA) of Kaposi's saroma-associated herpesvirus (KSHV) can maintain a plasmid containing the KSHV origin of DNA replication (oriP) as episomes in dividing human cells. Hence, LANA is considered to play crucial roles in persistent KSHV infection in human cells. In this study, we characterized a LANA fusion protein of green fluorescent protein (GFP-LANA). Like the wild-type LANA, GFP-LANA interacted tightly with mitotic chromosomes, and maintained the plasmid selectively with the KSHV oriP for more than three weeks in a human B cell line. Moreover, equivalent amount of GFP-LANA protein was segregated into two daughter cells in living metaphase cells. Our results suggested that the activity of LANA serves the segregation of equivalent amounts of viral genomes tethered with LANA into two daughter progeny cells during cell division. Thus, GFP-LANA is a useful tool for the analyses of the functions and dynamics of LANA in living cells.

PDZ domain-binding motif of human T-cell leukemia virus type 1 Tax oncoprotein augments the transforming activity in a rat fibroblast cell line

While human T-cell leukemia virus type 1 (HTLV-1) is associated with the development of adult T-cell leukemia (ATL), HTLV-2 has not been reported to be associated with such malignant leukemias. HTLV-1 Tax1 oncoprotein transforms a rat fibroblast cell line (Rat-1) to form multiple large colonies in soft agar, and this activity is much greater than that of HTLV-2 Tax2. We have demonstrated here that the increased number of transformed colonies induced by Tax1 relative to Tax2 was mediated by a PDZ domain-binding motif (PBM) in Tax1, which is absent in Tax2. Tax1 PBM mediated the interaction of Tax1 with the discs large (Dlg) tumor suppressor containing PDZ domains, and the interaction correlated well with the transforming activities of Tax1 and the mutants. Through this interaction, Tax1 altered the subcellular localization of Dlg from the detergent-soluble to the detergent-insoluble fraction in a fibroblast cell line as well as in HTLV-1-infected T-cell lines. These results suggest that the interaction of Tax1 with PDZ domain protein(s) is critically involved in the transforming activity of Tax1, the activity of which may be a crucial factor in malignant transformation of HTLV-1-infected cells in vivo.

Human T-cell leukemia virus type 1 Tax oncoprotein induces and interacts with a multi-PDZ domain protein, MAGI-3

Human T-cell leukemia virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia (ATL), whereas the closely related virus HTLV-2 has not been associated with such malignant conditions. HTLV-1 Tax1 oncoprotein transforms a rat fibroblast cell line (Rat-1) much more efficiently than does HTLV-2 Tax2. By using a differential display analysis, we isolated MAGI-3 as a Tax1-inducible gene in Rat-1 cells. Reverse transcription-polymerase chain reaction (RT-PCR) analysis confirmed that Tax1 induced MAGI-3 in Rat-1 cells. MAGI-3 has multiple PDZ domains and interacted with Tax1 but not Tax2 in 293T cells. The interaction of Tax1 with MAGI-3 was dependent on a PDZ domain-binding motif, which is missing in Tax2. The interaction of Tax1 with MAGI-3 altered their respective subcellular localization, and moreover, the interaction correlated well with the high transforming activities of Tax1 in Rat-1 cells relative to Tax2. MAGI-3 mRNA and the allied MAGI-1, but not MAGI-2, were expressed in HTLV-1-infected T-cell lines. Our results suggest that the interaction of Tax1 and MAGI-3 alters their respective biological activities, which may play a role in transformation by Tax1 as well as in the pathogenesis of HTLV-1-associated diseases.

Latency-associated nuclear antigen of Kaposi's sarcoma-associated herpesvirus interacts with human myeloid cell nuclear differentiation antigen induced by interferon alpha

Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpes virus type 8 (HHV-8) is tightly linked to the development of Kaposi's sarcoma, primary effusion lymphoma (PEL) and some cases of multicentric Castleman's disease. Latency-associated nuclear antigen (LANA) is one of a limited number of KSHV genes consistently expressed in these diseases as well as in KSHV-infected cell lines derived from PEL, and has been shown to play crucial role in persistence of KSHV genomes in the infected cells. In this study, we explored the cellular factors that interact with LANA using yeast two-hybrid screening, and isolated a part of gene encoding human myeloid cell nuclear differentiation antigen (MNDA). MNDA is a hematopoietic interferon-inducible nuclear proteins with a HIN-200 family member with conserved 200-amino acid repeats. Immunoprecipitation assay revealed that LANA interacted with MNDA in a mammalian embryonic kidney cell line. MNDA transcript was undetectable in three PEL cell lines by reverse-transcription polymerase chain reaction, but it was induced by interferon alpha (IFNalpha). Moreover, LANA and MNDA were co-localized in the nuclei of MNDA-expressing PEL cells. Our results suggest that LANA interacts with MNDA in KSHV-infected cells exposed to IFNalpha. Such interaction may modulate IFN-mediated host defense activities.

Chromosome binding site of latency-associated nuclear antigen of Kaposi's sarcoma-associated herpesvirus is essential for persistent episome maintenance and is functionally replaced by histone H1

Latency-associated nuclear antigen 1 (LANA1) of Kaposi's sarcoma-associated herpesvirus (KSHV; human herpesvirus 8) persistently maintains a plasmid containing the KSHV latent origin of replication (oriP) as a closed circular episome in dividing cells. In this study, we investigated the involvement of chromosome binding activity of LANA1 in persistent episome maintenance. Deletion of the N-terminal 22 amino acids of LANA1 (DeltaN-LANA) inhibited the interaction with mitotic chromosomes in a human cell line, and the mutant concomitantly lost activity for the long-term episome maintenance of a plasmid containing viral oriP in a human B-cell line. However, a chimera of DeltaN-LANA with histone H1, a cellular chromosome component protein, rescued the association with mitotic chromosomes as well as the long-term episome maintenance of the oriP-containing plasmid. Our results suggest that tethering of KSHV episomes to mitotic chromosomes by LANA1 is crucial in mediating the long-term maintenance of viral episomes in dividing cells.

Homotypic cell-cell adhesion induced by human T cell leukemia virus type 1 tax protein in T cell lines

Cell-cell adhesion is involved in the processes of cell growth, activation and migration, and inflammation. T cells infected with human T cell leukemia virus type 1 (HTLV-1) exhibit a high degree of homotypic cell-cell adhesion in vitro. In this study, we investigated the involvement of the viral protein Tax in such process. Expression of Tax in an interleukin (IL)-2-dependent mouse T cell line (CTLL-2) increased homotypic cell-cell adhesion; however, less cell adhesion was induced by Tax than that observed in HTLV-1-infected T cell lines. Moreover, Tax induced cell-cell adhesion in a human T cell line, in which the expression of Tax is inducible. Microscopic examination also revealed Tax-induced morphologic changes, including rounding of CTLL-2 cells, increased cell volume, and increased nucleus size. Taken together, our results suggest that Tax induces cell-cell adhesion and morphologic changes in HTLV-1-infected cells. Tax may thus play a role in persistent HTLV-1 infection and the pathogenesis of associated disease.

Human T-cell leukemia virus type 2 (HTLV-2) Tax protein transforms a rat fibroblast cell line but less efficiently than HTLV-1 Tax

Human T-cell leukemia virus type 1 (HTLV-1) and HTLV-2 are retroviruses with similar biological properties. Whereas HTLV-1 is the causative agent of an aggressive T-cell leukemia, HTLV-2 has been associated with only a few cases of lymphoproliferative disorders. Tax1 and Tax2 are the transcriptional activators of HTLV-1 and HTLV-2, respectively. Here we show that Tax2 transformed a Rat-1 fibroblast cell line to form colonies in soft agar, but the size and number of the colonies were lower than those of Tax1. Use of a chimeric Tax protein showed that the C-terminal amino acids 300 to 353 were responsible for the high transforming activity of Tax1. Activation of cellular genes by Tax1 through transcription factor NF-kappa B is reportedly essential for the transformation of Rat-1 cells. Tax2 also activated the transcription through NF-kappa B in Rat-1 cells, and such activity was equivalent to that induced by Tax1. Thus, the high transforming activity of Tax1 is mediated by mechanisms other than NF-kappa B activation. Our results showed that Tax2 has a lower transforming activity than Tax1 and suggest that the high transforming activity of Tax1 is involved in the leukemogenic property of HTLV-1.

Interleukin-2-dependent but not independent T-cell lines infected with human T-cell leukemia virus type 1 selectively express CD45RO, a marker for persistent infection in vivo

Human T-cell leukemia virus type 1 (HTLV-1) is an etiologic agent of adult T-cell leukemia. HTLV-1 is exclusively detected in CD45RO+ T-cells in infected individuals, but CD45RO is weakly expressed in HTLV-1-transformed T-cell lines in vitro. The aim of this study was to investigate the role of CD45RO in the persistent HTLV-1 infection in vivo. Flow cytometry showed that only two out of eight interleukin(IL)-2-independent HTLV-1-transformed T-cell lines expressed CD45RO, whereas all five IL-2-dependent ones expressed CD45RO, and the level of expression was higher in IL-2-dependent than in IL-2-independent cells. The high CD45RO expression in IL-2-dependent cell lines was not due to IL-2, since IL-2 had little effect on the expression of CD45RO in T-cell lines. Using western blotting, we showed that IL-2-dependent HTLV-1-transformed T-cell lines expressed a lower level of expression of the viral transcriptional regulatory protein Tax than IL-2-independent ones, and that the level of expression correlated inversely with that of CD45RO. However, the expression of Tax in one HTLV-1-negative T-cell line little affected the expression of CD45RO, suggesting that Tax at least alone does not suppress the expression of CD45RO in HTLV-1-infected T-cell lines, and that other viral or cellular factor(s) are probably involved in such suppression. Our results suggest that CD45RO+ Tax-low IL-2-dependent T-cell lines in vitro correspond to the persistent HTLV-1-infected cells in vivo, and HTLV-1-infected cells in vivo are immortalized in IL-2-dependent manner.

Human T-cell leukemia virus type 1 tax protein activates transcription through AP-1 site by inducing DNA binding activity in T cells

Human T-cell leukemia virus type 1 (HTLV-1) Tax protein induces the expression of various family members of the transcription factor AP-1, such as c-Jun, JunD, c-Fos, and Fra-1, at the level of RNA expression in T cells. We examined the activity of Tax in transcription through AP-1-binding sites (AP-1 site) in T cells. Transient transfection studies showed that Tax activated the expression of a luciferase gene regulated by two copies of an AP-1 site in the human Jurkat T-cell line. Tax activates the expression of viral and cellular genes through two different enhancers: a cAMP-responsive (CRE)-like element and a kappaB element. Two Tax mutants differentially activated expression of these two elements. Tax703 preferentially activated the kappaB element but not the CRE-like one, whereas TaxM22 showed the reverse. In addition, Tax703 and Tax, but not TaxM22, converted cell growth of a mouse T-cell line from being interleukin (IL)-2-dependent to being IL-2-independent. Unlike the wild-type Tax, Tax703 and TaxM22 only weakly activated the AP-1 site in the T-cell line. Thus, Tax seems to activate the AP-1 site via mechanisms distinct from those of kappaB or CRE-like elements, and the activation of the AP-1 site is dispensable for IL-2-independent growth of CTLL-2. Electrophoretic mobility shift assays showed that Tax induced strong binding activity to an AP-1 site in CTLL-2, whereas Tax703 did not, indicating that the induction of binding activity to the AP-1 site is essential for the transcriptional activation by Tax. The binding complex induced by Tax in CTLL-2 contained JunD and Fra-2. Other AP-1 proteins were undetectable. Activation of transcription through the AP-1 site in Jurkat cells by JunD and/or Fra-2 was weak. c-Jun, JunB, and c-Fos activation was greater, although the level was still less than that with Tax. Thus, the induction of AP-1 mRNA by Tax may not be sufficient for a complete activation of AP-1 site by Tax. Our results suggest that Tax activates the transcription of cellular genes with AP-1 sites by inducing the DNA-binding activity of AP-1 proteins in T cells, a mechanism distinct from those of CRE-like and kappaB elements.

Activation of oncogenic transcription factor AP-1 in T cells infected with human T cell leukemia virus type 1

Human T cell leukemia virus type 1 (HTLV-1) Tax protein transforms primary human T cells in vitro. We previously showed that Tax induces the expression of various family members of the transcription factor AP-1 such as c-Jun, JunD, c-Fos, and Fra-1 at the mRNA level in T cells. In this study, we have examined the ability of Tax to activate transcription through the AP-1-binding site (AP-1 site). A transient transfection study showed that Tax can activate transcription through the AP-1-binding site in a human T cell line, whereas any combination of AP-1 proteins did so much less than Tax, indicating that the activation of the AP-1 site by Tax may require a mechanism other than the induction of AP-1 mRNA. Fresh peripheral blood leukemia cells of all surveyed ATL patients displayed constitutive AP-1 DNA-binding activity, whereas no normal individuals did. However, the HTLV-1 genes, including tax, are not significantly expressed in fresh leukemia cells from ATL patients. Our present results suggest that activation of AP-1 occurs through Tax-dependent and -independent mechanisms in HTLV-1-infected T cells, which may play some roles in dysregulated phenotypes of HTLV-1-infected cells.

Contrasts in memory functions between adolescents with schizophrenia or ADHD

Previous research on memory and schizophrenia has relied on a limited number of global memory measures instead of a comprehensive assessment of various memory components. In addition, little effort has been directed at examining memory functioning in patients with early-onset schizophrenia. Published research often lacks a relevant neuropsychiatric comparison group to control for attention difficulties. Patients with Attention Deficit Hyperactivity Disorder (ADHD) were included in the present study for this purpose. To our knowledge, a direct comparison of the two patient groups on memory functions has never been made. In the present study, both adolescents with schizophrenia and adolescents with ADHD were compared on a comprehensive memory test battery. Nineteen adolescents with schizophrenia were compared to 20 ADHD adolescents and 30 normally functioning adolescents on measures of working memory and long-term episodic memory, including tests of verbal and visual memory, free recall and recognition memory. The performance of the adolescents with schizophrenia was impaired as compared to the normal group on most of the memory measures. They performed significantly more poorly than the adolescents with ADHD on the visual memory tests. The ADHD group scored more impaired than the schizophrenia group on working memory tests with focus on distractibility. The findings suggest a general memory deficit among adolescents with schizophrenia related to both verbal and visual material. Impairment on the measures of visual memory is specific to schizophrenia and does not characterise the ADHD subjects.

Neuropsychological deficits in adolescent-onset schizophrenia compared with attention deficit hyperactivity disorder

OBJECTIVE

Impaired neuropsychological performance involving abstraction-flexibility, memory, motor function, and attention has frequently been reported in schizophrenia as well as in attention deficit hyperactivity disorder (ADHD). This study represents an attempt to compare groups of adolescents with schizophrenia and ADHD on a comprehensive neuropsychological test battery. Such a comparison affords the opportunity to ascertain differences in the degree, profile, and specificity of impairments.

METHOD

The performance of 19 adolescents with schizophrenia, 20 adolescents with ADHD, and 30 normal adolescents on a broad battery of cognitive tests was compared.

RESULTS

The schizophrenic group showed the most pronounced deficits on tests of abstraction, visual memory, and motor function in comparison with the subjects with ADHD, while the ADHD subjects had the most pronounced deficits on measures of attention, verbal memory, and learning.

CONCLUSIONS

The subjects with schizophrenia appeared to have a more general pattern of brain dysfunction, whereas the impairment of the ADHD subjects seemed to be relatively specific to tests associated with frontal lobe function.

Auditory laterality and selective attention: normal performance in patients with early-onset schizophrenia

In this study, auditory laterality and selective attention were examined in patients with early-onset schizophrenia using a dichotic listening (DL) test. Deficient performance on this test has repeatedly been found in adult patients with chronic schizophrenia, indicating abnormalities in left hemisphere function. The hypothesis in the present study was that subjects with early-onset schizophrenia manifest deficits in DL test performance similar to adult chronic patients. A group of 19 patients with early-onset schizophrenia were compared with a group of 20 adolescents with attention-deficit hyperactivity disorder and a group of 30 normal adolescents. Results indicated no significant differences between the three groups on any of the measures. Alternative hypotheses are put forth to explain the findings, among them that deficits in DL performance may be secondary to long-time illness and/or drug treatment, and that these deficits may become apparent only after interaction with maturational neurodevelopmental changes during adolescence.

Covert visual attention in patients with early-onset schizophrenia

The aim of the present study is to examine attentional costs (inhibition) in covert visual attention in a group of acutely ill adolescents with schizophrenia without long histories of neuroleptic treatment. Variations in reaction time were analyzed for possible age and sex differences. Adolescents with schizophrenia (n = 19) were compared to a group of ADHD subjects (n = 20) and a group of normally functioning adolescents (n = 30) on a measure of covert visual attention. The results support a hypothesis of abnormally rapid disengagement (reduced costs) in male adolescents with schizophrenia. Such an abnormality has also been found in adults with chronic schizophrenia. Whether this holds true for both sexes of adolescents with schizophrenia or is restricted to male subjects cannot be answered with certainty due to the small number of females with schizophrenia in our sample. Our findings indicate, however, that there are some general sex differences and some specific sex differences related to covert visual attention in adolescents with schizophrenia.

No vigilance deficit found in either young schizophrenic or ADHD subjects

Vigilance deficits have been found in both schizophrenic and ADHD subjects. The two patient groups have never been directly compared on any vigilance measure, however. In the present study 20 early-onset schizophrenics were compared to 20 ADHD adolescents on a Degraded Stimulus Continuous Performance Test (DS-CPT). A comparison group of 30 normal adolescents was also included. Results showed no significant differences between the three groups on any of the DS-CPT measures. Different hypotheses are put forth to explain the findings, among them that the task may be insensitive to identifying sustained attention deficits in adolescent populations.

Backward-masking deficit in adolescents with schizophrenic disorders or attention deficit hyperactivity disorder

OBJECTIVE

Backward masking is a cognitive task that involves the earliest phases of visual information processing. Disrupted task performance caused by a visual mask has been found repeatedly in schizophrenic patients; however, the specificity to schizophrenia of deficits in backward masking has received only limited study.

METHOD

In this study 20 patients with early-onset schizophrenic disorders were compared to 20 adolescents with attention deficit hyperactivity disorder (ADHD) and 30 normal adolescents on a two-digit identification task in three backward-masking conditions: no mask, a short stimulus interval (33.0 msec), and a long stimulus interval (49.5 msec).

RESULTS

The performance of the two groups of patients was similar, and both groups showed a statistically significant masking deficit after the long stimulus interval and a nearly significant deficit after the short stimulus interval in comparison with the normal subjects.

CONCLUSIONS

Increased vulnerability to the masking stimulus was confirmed in schizophrenic subjects, but it is not specific to schizophrenia and is not accounted for by psychotic symptoms alone, since the subjects with ADHD performed similarly.

Neutralizing epitope on penetration protein of vaccinia virus

The monoclonal antibody 2D5 neutralized vaccinia virus by preventing penetration of the virus and reacting with VP23-29K. The conformation of the VP23-29K was maintained by a disulfide bond(s), and the 2D5mAb reacted stronger with the nonreduced 23-kDa form than with the reduced 29-kDa form. We selected several escape mutants. Sequences of the A17L genes, which were thought to encode the VP23-29K, did not show cognate mutation. Genomic DNA of a 2D5mAb-resistant mutant (M4) was cleaved with HindIII, and all the fragments were introduced into parental IHD-J strain vaccinia virus by transfection. Only the L fragment produced a 2D5mAb-resistant virus. Dissection of the L fragment and subsequent transfection revealed that the L1R gene induced the 2D5mAb-resistant virus. The 2D5mAb-resistant mutants showed a consensus G to A conversion at nucleotide 101 of their LIRs which would replace asparatic acid 35 with asparagine. Ishibashi-111 strain mousepox virus spontaneously resistant to 2D5mAb also had the same sequence at this region. Moreover, the VP23-29K was myristoylated as predicted by the L1R gene. The coding gene of the VP23-29K was L1R.

Expressed emotion, communication deviance and schizophrenia. An exploratory study of the relationship between two family variables and the course and outcome of a psychoeducational treatment programme

The relationship between expressed emotion (EE) and communication deviance (CD), and outcome in a group of early-onset schizophrenics after 2 years of psychoeducational treatment was examined. Patients' parents were assessed on EE and CD before and after the 2-year period. Outcome was measured by Global Assessment Scale (GAS) and relapse rate. Results showed that the correlation between CD and outcome was higher than between EE and outcome. In most of the patients who improved their GAS score during the treatment programme, their parents changed from high to low EE. CD proved to be more resistant to psychosocial intervention than EE.

Identification of a vaccinia virus penetration protein

A vaccinia virus structural protein responsible for infection was identified by monoclonal antibodies (mAb). Two mAbs (2D5 and 8C2) neutralized the virus at a dilution of about 10(5). The 2D5 mAb reacted with VP29K under standard immunoblotting conditions and with a 23-kDa protein when virus was dissociated under nonreducing conditions. The 8C2 mAb reacted with the 23-kDa protein, but not with VP29K. Two-dimensional electrophoresis demonstrated that the 23-kDa protein was the nonreduced form of VP29K. Since they possess the same N-terminal amino acid sequence, the protein was renamed VP23-29K. The gene that encoded it was HindIII A17L ORF. The VP23-29K-dependent process of infection did not occur during the adsorption phase at 4 degrees, and trypsin-treated virus could complete the process within 10 min at 37 degrees. One half of the trypsin-treated intracellular mature virus (IMV) achieved the process within 20 min, but for normal IMV this time period was 2 hr. VP23-29K had function for the early step of penetration, and the functional site in the nonreduced 23-kDa form was masked to some extent in normal virus. The late cell fusion by the fusion positive (F+) D1 mutant proceeded in neutral pH. Cells infected with F- IHD-J strain virus did not fuse, but a short treatment with pH 5 medium developed cell fusion. Both of the cell fusions were inhibited by the 2D5 and 8C2 mAbs. Virion VP23-29K was suggested to be the fusion protein for the early penetration and the late cell fusion phases of vaccinia infection cycle.

N-terminal amino acid sequences of vaccinia virus structural proteins

The N-terminal amino acid sequences of vaccinia virus structural proteins were determined by direct sequencing following separation of the proteins of purified intracellular mature virus by SDS-polyacrylamide gels. By comparing the sequences obtained with the published vaccinia virus DNA sequences, specific open reading frames (ORFs) were identified. The structural proteins were encoded by the ORFs of HindIII, A3L (VP57K, 32K), A10L (VP62K, VP28K, VP22K), A12L (VP10K, VP4K), A13L (VP14K), A14L (VP17-25K), A17L (VP23-29K), A27L (VP13.8K), D8L (VP32K), H3L (VP34-37K), L4R (VP27K), G7L (VP16K), and 15L (VP13K). Four virus membrane proteins contained transmembrane signals. The N-termini of proteins indicated four types of cleavages. Ala-Gly-specific cleavage associated with products of six ORFs. Phe-specific cleavage was found in two, Met-specific in three, and Arg-specific in the product of one ORF. Ala-Gly-specific cleavage processes seven core proteins encoded by five ORFs and one membrane protein. The Met- and Arg-specific cleavages are suggested to be nonessential for virus assembly because the major portions of the target membrane proteins remain unaffected.

Application of total quality management to unit-based quality assessment and improvement

The paradigm is shifting in health care. The current emphasis is on total quality management (TQM). The authors describe a model, Quality in Daily Work (QIDW), which may be used to assist in the implementation of TQM at the unit level. QIDW is patterned after Juran's Trilogy of quality planning, quality control, and quality improvement.

Autonomous staff selection teams

Although some other organizations encourage staff input into employee selection, the advanced care department at Bellin Hospital in Green Bay, Wisconsin has taken this concept to a new level by implementing an autonomous interview team. This team is empowered to make hiring decisions for all positions within the department without management influence or interference.

The function of the vaccinia hemagglutinin in the proteolytic activation of infectivity

The vaccinia virus hemagglutinin (HA) has specific affinity for the structural protein, VP37K. The nature of this affinity and its relationship to the function of the HA were analyzed using HA mutants. The VP37K reactive site of the HA molecule is located in its transmembrane region, and the vaccinia virus HA associates with the viral particle via the VP37K-HA affinity. The viruses possessing an HA with fusion inhibitor activity were largely of the low infectivity form, whereas the viruses that associated mutant HAs defective in the activity were of the high infectivity form. D1 mutant virus does not produce HA. When it was incubated with the HA of the IHD-J strain, the HA associated with the virus particle. The HA-loaded D1 mutant virus acquired a high affinity not only for chick erythrocytes but also for KB and Vero cells. At the same time, the infectivity for Vero cells was decreased. The original high infectivity was recovered by treatment with trypsin. The virion-associated vaccinia HA has two functions; the HA protects the infectivity of the virus by the fusion inhibitor activity and exhibits affinity against host cells. Vaccinia virus first adsorbs to the cell via HA, and then proteolysis of the HA activates the second adsorption site which seems to be the fusogenic site of the virus. Proteolytic activation represents removal of the fusion inhibitor activity of the HA.

Hemadsorption and fusion inhibition activities of hemagglutinin analyzed by vaccinia virus mutants

Vaccinia virus IHD-J strain induces hemagglutinin (HA) on the surface membrane of infected cells and does not elicit cell-cell fusion (F-). We isolated 21 independent hemadsorption-negative (HAD-) mutant viruses from IHD-J and five HAD+ revertants from one of these mutants. Of the 21 mutants, 19 that synthesized either no or little HA at the cell surface caused cell-cell fusion (F+), whereas none of the five revertants that synthesized HA at the cell surface induced cell-cell fusion. Furthermore, anti-HA monoclonal antibody B2D10 induced extensive polykaryocytosis of IHD-J-infected cells and suppressed the ability of the IHD-J-infected cell extract to inhibit the polykaryocytosis induced by IHD-W. The other 2 of the 21 HAD- mutants, B1 and A2, which induced HAs at the cell surface, showed F- and F+ phenotype, respectively. The HA molecule of mutant B1 had a single amino acid substitution of Lys for Glu-121 in its extracellular domain, whereas that of mutant A2 had a single substitution mutation of Tyr for Cys-103. We conclude that the vaccinia HA is a fusion inhibition protein, that the active sites for the two activities reside separately in its extracellular domain, and that cysteine-103 is important in forming the proper tertiary structure of the protein to exert both activities.

Hemadsorption and fusion inhibition activities of hemagglutinin analyzed by vaccinia virus mutants

Vaccinia virus IHD-J strain induces hemagglutinin (HA) on the surface membrane of infected cells and does not elicit cell-cell fusion (F-). We isolated 21 independent hemadsorption-negative (HAD-) mutant viruses from IHD-J and five HAD+ revertants from one of these mutants. Of the 21 mutants, 19 that synthesized either no or little HA at the cell surface caused cell-cell fusion (F+), whereas none of the five revertants that synthesized HA at the cell surface induced cell-cell fusion. Furthermore, anti-HA monoclonal antibody B2D10 induced extensive polykaryocytosis of IHD-J-infected cells and suppressed the ability of the IHD-J-infected cell extract to inhibit the polykaryocytosis induced by IHD-W. The other 2 of the 21 HAD- mutants, B1 and A2, which induced HAs at the cell surface, showed F- and F+ phenotype, respectively. The HA molecule of mutant B1 had a single amino acid substitution of Lys for Glu-121 in its extracellular domain, whereas that of mutant A2 had a single substitution mutation of Tyr for Cys-103. We conclude that the vaccinia HA is a fusion inhibition protein, that the active sites for the two activities reside separately in its extracellular domain, and that cysteine-103 is important in forming the proper tertiary structure of the protein to exert both activities.

Epitope mosaic on the surface proteins of orthopoxviruses

Epitopes on the surface components of orthopoxviruses were analyzed with monoclonal antibodies (MAbs) against monkeypox and vaccinia viruses by enzyme-linked immunosorbent assay (ELISA), Western blotting (WB), radioimmunoprecipitation (RIP), and competitive binding inhibition assay (CBIA). When compared by ELISA, three vaccinia virus strains exhibited a similar reactivity to 99 tested MAbs despite their remote passage history. All five isolates of monkeypox virus closely resembled one another, irrespective of the host species (human, monkey, squirrel) from which they were isolated. Taterapox virus reacted similar to vaccinia virus against 97 of the 99 tested MAbs, and reacted with 2 MAbs which were cross-reactive with monkeypox and mousepox. Mousepox and cowpox viruses reacted with these MAbs in a species-specific manner: MAbs reactive to cowpox virus distinctly differ from those reactive to mousepox virus. Of the 99 tested MAbs, 32 reacted with all the 11 tested orthopoxviruses, indicating that the corresponding epitopes existed in all the viruses. Fifty-four MAbs reacted with two or more virus species and were classified as partially common MAbs. Eight MAbs were apparently type-specific for monkeypox, and five were specific for vaccinia and taterapox viruses. No strain-specific epitope was detected. Sera of monkeypox-infected patients, when analyzed by CBIA, interfered with the binding of monkeypox-specific MAb H12C1 but not of vaccinia-specific MAb G6C6. Sera of monkeypox-infected patients who had been vaccinated competed against both MAbs, demonstrating the original antigenic sin phenomenon. The two MAbs could distinguish between the sera of monkeypox patients and those of vaccinated persons. However, the serum of a smallpox patient was competitive against these apparently vaccinia- or monkeypox-specific MAbs. Three of the eight monkeypox-specific epitopes were recognized by the above CBIA test, which suggests that they also exist in smallpox virus. The mosaic-like combination of common epitopes and the small number of type-specific epitopes manifested the antigenic characteristics of orthopox viruses. The species boundary was obscured due to the partially common epitopes, but the total composition of epitopes was stable enough to maintain the antigenic species-specificity. The mutual relationship of the orthopoxviruses was visualized in a three-dimensional network.

Modification of vaccinia virus penetration proteins analyzed by monoclonal antibodies

Modifications induced in structural vaccinia virus proteins that elicit the high infectious state by virus activating treatments involving trypsin and phosphatidylserine were analyzed using antivaccinia monoclonal antibodies (MABs). MABs reactive against each of the five outer layer proteins (VP54K, 34K, 32K, 29K, and 17K-25K) neutralized infectivity. VP54K possesses at least two neutralizing epitopes. Treatment with trypsin or with isolated plasma membrane cleaved VP54K into TVP41K carrying epitope A and removed a fragment containing epitope B from the virus. MABs against either of the epitopes could neutralize the virus. The exposure of epitope A concomitantly activated virus infectivity, and it was an essential step of penetration. MABs against VP17K-25K reacted more efficiently with trypsin-treated virus than with untreated virus, but the size of VP17K-25K was not affected by trypsin; this finding indicated that trypsin treatment rendered the VP17K-25K epitopes more accessible to antibody and hence to neutralization. MABs against VP32K and VP29K neutralized infectivity to the same extent irrespective of the state of activation. Virus treated with phosphatidylserine (PS) was neutralized more efficiently by MAB against VP34K than untreated virus, but the amount of antibody that reacted with the virus was the same before and after treatment with PS. Phosphatidylserine did not modify epitope structure itself, but it activated the function of VP34K. It was concluded that blocking of the functions attributed to any of the five proteins resulted in neutralization of virus infectivity, and treatment with trypsin and phosphatidylserine activates infectivity of vaccinia virus by modifying three of them (VP54K, VP34K, VP17K-25K) with characteristic behavior for each protein.

Reversible inactivation and reactivation of vaccinia virus by manipulation of viral lipid composition

The role of phospholipids in vaccinia virus was investigated by substituting viral lipids with specific phospholipids. Treatment of virus with sodium dodecyl sulfate, sodium deoxycholate, or Nonidet-P40 (NP-40) resulted in almost complete removal of viral lipid and led to inactivation of the virus. The inactivation induced by the former two was irreversible, but NP-40-treated virus was reactivated upon reassociation with phospholipids. Individual phospholipids, including phosphatidylserine (PS), phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, lysolecithin, sphingomyelin, and acyl bis(monoacylglycero)phosphate (ABMP), were tested for ability to reactivate NP-40-treated virus. Reactivation was induced only by PS. The infectivity of virus that had been treated with NP-40 and then with PS was unstable; the reactivated virus was inactivated within a short period. It was also very sensitive to trypsin. Treatment of NP-40-treated virus with mixtures of PS and ABMP yielded virus that was more resistant to spontaneous and trypsin-induced inactivation. Thus, PS appears to be an essential for infectivity and ABMP appears to play a supplementary role for maintenance of infectivity, perhaps by protecting against inactivating factors.