Ichiro Kurane

Definition of an epitope on Japanese encephalitis virus (JEV) envelope protein recognized by JEV-specific murine CD8+ cytotoxic T lymphocytes

Summary. We defined an epitope on the Japanese encephalitis virus (JEV) envelope (E) protein recognized by CD8+ cytotoxic T lymphocytes (CTLs). CTLs induced in JEV-infected BALB/c (H-2d) mice recognized E and/or premembrane (PrM) proteins, while CTLs in C57BL/6J (H-2b) and C3H/HeJ (H-2k) mice did not. JEV-specific CTLs had a phenotype of CD3+ CD4− CD8+. Twenty-four 9-amino acid (a.a.) peptides, which had binding motifs for H-2Kd, H-2Ld or H-2Dd, were synthesized according to the amino acid sequences of PrM and E proteins. CTLs induced by JEV infection recognized only the peptide K-3. Immunization of BALB/c mice with only a group of peptides including K-3 induced CTLs which recognized the homologous K-3 peptide, while immunization with other peptides did not. The peptide K-3 had a binding motif for H-2Kd. This is consistent with the finding that JEV-specific CTLs in BALB/c mice was H-2Kd-restricted.These results indicate that the epitope recognized by CTLs in BALB/c mice is located between a.a. 60 and 68 on the E protein, corresponding to an a.a. sequence of CYHASVTDI.

Serum antibodies to human herpesvirus 7, human herpesvirus 6 and cytomegalovirus in patients with idiopathic facial nerve palsy or sudden deafness

The aetiology of idiopathic facial nerve palsy (Bells palsy) and sudden deafness are not known, although viruses have been suspected as a cause of them. We investigated the relationship between Bells palsy or sudden deafness, and reactivation of cytomegalovirus, human herpesvirus 6 (HHV-6) and 7 (HHV-7). Paired sera were collected from 22 patients with Bells palsy and 24 patients with sudden deafness. IgG antibody titres to HHV-7 were increased in one patient with Bells palsy. IgG antibody titres to HHV-6 were increased in one patient with Bells palsy and two with sudden deafness. IgG antibody titres to cytomegalovirus were increased in one patient with sudden deafness. Titres of the three viral antibodies were not increased simultaneously in any patients. These viruses may contribute to the development of Bells palsy or sudden deafness in some cases. It is, however, unlikely that these viruses are the main cause of Bells palsy and sudden deafness in the majority of patients.

Electron microscopic study of human immunodeficiency virus type 1 (HIV-1) core structure: two RNA strands in the core of mature and budding particles

SummaryThe basic structure of human immunodeficiency virus type 1 (HIV-1) has been investigated morphologically; however, the internal structure of HIV-1 core is not well understood. We studied the internal structures by transmission electron microscopy. We modified the method for electron staining of ultrathin sections and processed electron microscopic photographs using a computer. We confirmed that a mature HIV-1 particle had two copies of RNA strands in a cone-shaped core. These two RNA strands formed a coiling structure and interwound each other, and were already present in the late budding stage.