Koichi Yamanishi

IDENTIFICATION OF HUMAN HERPESVIRUS-6 AS A CAUSAL AGENT FOR EXANTHEM SUBITUM

A virus was isolated from the peripheral blood lymphocytes of patients with exanthem subitum, cultured successfully in cord blood lymphocytes, and shown to be antigenically related to human herpesvirus-6 (HHV-6). Morphological features, as studied by thin-section electronmicroscopy, resembled those of herpes group viruses. Convalescent-phase serum samples, tested against the new viral antigen and HHV-6 antigen, showed seroconversion. The results strongly suggest that the newly isolated virus is identical or closely related to HHV-6 and the causal agent for exanthem subitum.

SOCS-1 Participates in Negative Regulation of LPS Responses

SOCS-1 is a negative regulatory molecule of the JAK-STAT signal cascade. Here, we demonstrate that SOCS-1 is a critical downregulating factor for LPS signal pathways. SOCS-1 expression was promptly induced in macrophages upon LPS stimulation. SOCS-1-deficient mice were highly sensitive to LPS-induced shock and produced increased levels of inflammatory cytokines. Introduction of SOCS-1 inhibited LPS-induced NF-kappaB and STAT1 activation in macrophages. Furthermore, LPS tolerance, a refractory state to second LPS stimulation, was not observed in SOCS-1-deficient mice. These results suggest SOCS-1 as an essential, negative regulator in LPS responses that protects the host from harmful overresponses to LPS and may provide new insight into the endotoxin-induced fatal syndrome that occasionally occurs following infection.

Latent human herpesvirus 6 infection of human monocytes/macrophages

Human herpesvirus 6 (HHV-6) DNA was detected in peripheral blood from exanthem subitum patients during the acute and convalescent phases of infection using the polymerase chain reaction. Although DNA could be detected in non-adherent and adherent mononuclear cells during the acute phase, it was detected predominantly in adherent cells during the convalescent phase; furthermore, viral DNA was found in adherent cells of healthy adults. When adherent mononuclear cells were cultured in vitro, virus was found to replicate well in differentiated cells cultured for 7 days in vitro before infection. When cells were cultured for more than 1 month, no detectable antigen and no evidence of virus growth was observed, but viral DNA could be detected. These apparently latently infected monocytes were treated with phorbol ester, after which virus could be recovered from the cultures. Therefore, we have developed an in vitro latency system for HHV-6; our results suggest that HHV-6 may latently infect monocytes in vivo and in vitro and that it may be reactivated in cells by some factors.

Human herpesvirus 7: Another causal agent for roseola (exanthem subitum)

Human herpesvirus 7 (HHV-7) was isolated from peripheral blood mononuclear cells of two infants with typical exanthem subitum. The HindIII-, BamHI-, and EcoRI-digested DNA patterns of the isolated viruses were very similar to that of the prototype HHV-7 (RK strain), but different from that of human herpesvirus 6 (HHV-6). During the convalescent period of the first patient, the titer of antibody to HHV-7 rose from < 1:10 to 1:320 by an immunofluorescence antibody test, whereas the titer of antibody to HHV-6 remained < 1:10. In the second patient, who had two independent episodes of exanthem subitum during 2 months, both HHV-6 and HHV-7 were sequentially isolated; seroconversion to HHV-6 occurred during the first episode and to HHV-7 during the second episode. In addition, sera from another 15 children who had episodes of exanthem subitum were serologically tested for antibodies to HHV-6 and HHV-7 by immunofluorescence antibody test. Five of seven patients had seroconversion to HHV-7 just after having typical signs and symptoms of exanthem subitum. These results suggest that HHV-7 is one of the causative agents of exanthem subitum.

Human Herpesviruses: Biology, Therapy, and Immunoprophylaxis

Part I. Introduction Part II. Basic Virology and Viral Gene Effects on Host Cell Functions Part II. Basic Virology and Viral Gene Effects on Host Cell Functions Part II. Basic Virology and Viral Gene Effects on Host Cell Functions Part III. Pathogenesis, Clinical Disease, Host Response, and Epidemiology Part III. Pathogenesis, Clinical Disease, Host Response, and Epidemiology Part III. Pathogenesis, Clinical Disease, Host Response, and Epidemiology Part III. HHV- 6a, 6b and 7 Ann Arvin and Richard Whitley Part III. Pathogenesis, Clinical Disease, Host Response, and Epidemiology Part IV. Non-Human Primate Herpesviruses Ann Arvin, Patrick Moore and Richard Whitley Part V. Subversion of Adaptive Immunity Richard Whitley and Ann Arvin Part VI. Antiviral Therapy Richard Whitley Part VII. Vaccines and Immunotherapy Ann Arvin and Koichi Yamanishi Part VIII. Herpes as Therapeutic Agents Richard Whitley and Bernard Roizman.

Human Herpesvirus 6 Infection In Renal Transplantation

The relationship between renal transplantation and human herpesvirus 6 (HHV-6) infection was studied. All 21 kidney donors examined had antibody to HHV-6 at the time of transplantation. The 21 kidney recipients also had detectable antibody to HHV-6 before transplantation--and, of these, 8 patients showed a significant increase of serum antibody titer against HHV-6 after transplantation. All these 8 recipients suffered severe kidney rejection. Furthermore, virus isolation from peripheral blood lymphocytes of 2 recipients who suffered rejection was attempted, and in both cases HHV-6 was isolated. Biopsy specimens of rejected kidneys of 9 other patients were examined for the presence of HHV-6 antigens, and in 5 of these specimens antigens were detected in the tubular epithelium, as well as in infiltrating histiocytes and lymphocytes. These results suggest that HHV-6 can infect renal tissues and that the infection may be correlated with rejection or with immunosuppressive therapy.

Importance of collateral circulation for prevention of left ventricular aneurysm formation in acute myocardial infarction.

The effect of preexistent coronary collateral perfusion on the prevention of left ventricular aneurysm formation was examined in 47 patients undergoing an intracoronary thrombolysis within 6 hours after the onset of a first acute anterior myocardial infarction. Left ventricular aneurysm formation and wall motion were analyzed with cineventriculography. A left ventricular aneurysm was determined as well-defined demarcation of the infarcted segment from normally contracting myocardium. In 25 patients with successful thrombolysis (group A), a left ventricular aneurysm was observed in one patient (4%) during the chronic stage of infarction. In 10 patients who had a significant collateral circulation to the infarct-related coronary artery and unsuccessful reperfusion (group B), the left ventricular aneurysm was observed in only one patient (10%). In the remaining 12 patients with unsuccessful recanalization in the absence of a significant collateral perfusion (group C), there was a higher incidence (seven of 12, 58%) of left ventricular aneurysm formation than in groups A and B (p less than 0.05). In group A, both the global ejection fraction and regional wall motion in the infarct areas improved significantly (p less than 0.05) between the acute and chronic stages of infarction. By contrast, in groups B and C, these indexes on the ventricular function did not change significantly during the convalescent period. Thus, although the collateral perfusion existing at the onset of acute myocardial infarction may not improve ventricular function, it exerts a beneficial effect on the prevention of left ventricular aneurysm formation.

Comparison of the Complete DNA Sequences of the Oka Varicella Vaccine and Its Parental Virus

ABSTRACT The DNA sequences of the Oka varicella vaccine virus (V-Oka) and its parental virus (P-Oka) were completed. Comparison of the sequences revealed 42 base substitutions, which led to 20 amino acid conversions and length differences in tandem repeat regions (R1, R3, and R4) and in an origin of DNA replication. Amino acid substitutions existed in open reading frames (ORFs) 6, 9A, 10, 21, 31, 39, 50, 52, 55, 59, 62, and 64. Of these, 15 base substitutions, leading to eight amino acid substitutions, were in the gene 62 region alone. Further DNA sequence analysis showed that these substitutions were specific for V-Oka and were not present in nine clinical isolates. The immediate-early gene 62 product (IE62) of P-Oka had stronger transactivational activity than the mutant IE62 contained in V-Oka in 293 and CV-1 cells. An infectious center assay of a plaque-purified clone (S7-01) from the V-Oka with 8 amino acid substitutions in ORF 62 showed smaller plaque formation and less-efficient virus-spreading activity than did P-Oka in human embryonic lung cells. Another clone (S-13) with only five substitutions in ORF 62 spread slightly faster than S7-01 but not as effectively as P-Oka. Moreover, transient luciferase assay in 293 cells showed that transactivational activities of IE62s of S7-01 and S7-13 were lower than that of P-Oka. Based on these results, it appears that amino acid substitutions in ORF 62 are responsible for virus growth and spreading from infected to uninfected cells. Furthermore, the Oka vaccine virus was completely distinguishable from P-Oka and 54 clinical isolates by seven restriction-enzyme fragment length polymorphisms that detected differences in the DNA sequence.

Human Herpesvirus 7 Open Reading Frame U12 Encodes a Functional β-Chemokine Receptor

ABSTRACT Human herpesvirus 7 (HHV-7), which belongs to the betaherpesvirus subfamily, infects mainly CD4+ T cells in vitro and infects children during infancy. After the primary infection, HHV-7 becomes latent. HHV-7 contains two genes (U12 and U51) that encode putative homologs of cellular G-protein-coupled receptors. To analyze the biological function of the U12 gene, we cloned the gene and expressed the U12 protein in cells. The U12 gene encoded a calcium-mobilizing receptor for the EBI1 ligand chemokine-macrophage inflammatory protein 3β (ELC/MIP-3β) but not for other chemokines, suggesting that the chemokine selectivity of the U12 gene product is distinct from that of the known mammalian chemokine receptors. These studies revealed that U12 activates distinct transmembrane signaling pathways that may mediate biological functions by binding with a β-chemokine, ELC/MIP-3β.

Octamer-Binding Sequence Is a Key Element for the Autoregulation of Kaposi's Sarcoma-Associated Herpesvirus ORF50/Lyta Gene Expression

ABSTRACT The expression of the Kaposis sarcoma-associated herpesvirus (KSHV) open reading frame 50 (ORF50) protein, Lyta (lytic transactivator), marks the switch from latent KSHV infection to the lytic phase. ORF50/Lyta upregulates several target KSHV genes, such as K8 (K-bZip), K9 (vIRF1), and ORF57, finally leading to the production of mature viruses. The auto-upregulation of ORF50/Lyta is thought to be an important mechanism for efficient lytic viral replication. In this study, we focused on this autoregulation and identified the promoter element required for it. An electrophoretic mobility shift assay indicated that the octamer-binding protein 1 (Oct-1) bound to this element. Mutations in the octamer-binding motif resulted in refractoriness of the ORF50/Lyta promoter to transactivation by ORF50/Lyta, and Oct-1 expression enhanced this transactivation. These results suggest that the autoregulation of ORF50/Lyta is mediated by Oct-1.