Yasufumi Hidaka

Measles Viruses on Throat Swabs from Measles Patients Use Signaling Lymphocytic Activation Molecule (CDw150) but Not CD46 as a Cellular Receptor

ABSTRACT Both CD46 and signaling lymphocytic activation molecule (SLAM) have been shown to act as cellular receptors for measles virus (MV). The viruses on throat swabs from nine patients with measles in Japan were titrated on Vero cells stably expressing human SLAM. Samples from all but two patients produced numerous plaques on SLAM-expressing Vero cells, whereas none produced any plaques on Vero cells endogenously expressing CD46. The Edmonston strain of MV, which can use either CD46 or SLAM as a receptor, produced comparable titers on these two types of cells. The results strongly suggest that the viruses in the bodies of measles patients use SLAM but probably not CD46 as a cellular receptor.

Glycoprotein C of herpes simplex virus type 1 is essential for the virus to evade antibody-independent complement-mediated virus inactivation and lysis of virus-infected cells

Glycoprotein C (gC) of herpes simplex virus type 1 (HSV-1) is a receptor for the complement component C3b. We have previously isolated HSV-1 gC- strains (TN1, TN2 and TN3) from a patient with recurrent keratitis at three different times. These are very rare isolates because gC was thought to be essential for the virus in vivo. To determine whether gC modifies the interaction of complement with cell-free virus or virus-infected cells, we constructed gC+ recombinant viruses in which the intact gC gene of strain KOS was inserted into the TN1 virus genome. TN1 virus was inactivated by complement and TN1 virus-infected cells were lysed by complement; however, gC+ recombinant viruses became resistant to these effects of complement. These results suggest a role for gC in protection of both the virion envelope and the infected cell surface against damage by complement. TN1 virus was inactivated by complement from rats (Wistar, WKA, F344 and SD), guinea-pigs (Hartley) and humans, but not by complement from mice (C3H, DDD and BALB/c), which indicates that mice seem to be inappropriate as an experimental model for the study of HSV infection in which complement factors need to be considered.

Characterization of glycoprotein C-negative mutants of herpes simplex virus type 1 isolated from a patient with keratitis

SummaryRecently three strains of herpes simplex virus type 1 (HSV-1), which did not react with MicroTrak Herpes (Syva Co.), were isolated by us from a patient with recurrent herpetic keratitis. In this study we characterized these strains of HSV-1 and found them to be HSV-1 gC− mutants which are very rare isolates from humans. The properties of the HSV-1 strains regarding plaque morphology on Vero cells and chick embryo fibroblasts and viral DNA analysis were the same as those of the usual HSV-1 strains. An immunofluorescence study using anti-gC-1 monoclonal antibody and SDS-PAGE analysis of radiolabeled viral glycoproteins showed that these strains are deficient in gC-1. They were virulent for mice and sensitive to acyclovir and bromovinyldeoxyuridine. Furthermore the infectivity of the strains was inactivated by complement though the phenomenon was not observed in the usual HSV-1 strains. This finding suggests that protection from damages by complement is an important function of gC. In keratitis the effects of complement are thought to be minimal because of the scanty blood supply and this may be the reason why these strains were isolated from the cornea.

Breast Milk Is Not a Significant Source for Early Epstein-Barr Virus or Human Herpesvirus 6 Infection in Infants: A Seroepidemiologic Study in 2 Endemic Areas of Human T-Cell Lymphotropic Virus Type I in Japan

In order to evaluate the possibility of Epstein‐Barr virus (EBV) and human herpesvirus 6 (HHV‐6) transmission via breast milk, a total of 331 serum specimens collected from bottle‐fed and breast‐fed children and their mothers, in 2 endemic areas of human T‐cell lymphotropic virus type I (HTLV‐I) in Japan, were assayed for antibodies to EBV and HHV‐6. The seroprevalences of EBV and HHV‐6 were over 95% both in the mothers of bottle‐fed children and in those of breast‐fed children. The seroprevalence of EBV at 12–23 months of age was 54.5% (36/66) and 55.8% (24/43) in breast‐fed children and bottle‐fed children, respectively. The seroprevalence of HHV‐6 at 12–23 months of age was 90.9% (60/66) and 93.0% (40/43) in breast‐fed children and bottle‐fed children, respectively. No difference was observed between the seroprevalences of EBV and HHV‐6 in breast‐fed and bottle‐fed children at 12–23 months of age. Our seroepidemiologic data indicate that breast milk is not a significant source of early EBV or HHV‐6 infection in infancy.

Five Cases of Measles Secondary Vaccine Failure with Confirmed Seroconversion after Live Measles Vaccination

We report 5 patients with secondary vaccine failure (SVF) who were infected with natural measles 2, 5, 5, 7 and 12 years, respectively, after vaccination with further attenuated live measles vaccine during infancy. Their seroconversion had been confirmed after vaccination. Three of the 5 patients had mild (modified) measles, while the remaining 2 patients had typical measles. The hemagglutination inhibition antibody titers to measles virus in paired acute and convalescent sera showed a secondary response pattern in 4/5 patients, and a primary response pattern was present in the remaining patient. Measles IgM antibodies were present in all patients during the convalescent stage. The patient with the primary response pattern may have had a decrease in the B cell memory during the 5-year period between vaccination and infection. This may be the first SVF case report that confirms the existence of completely waning immunity in recipients of the further attenuated live measles vaccines.

Twenty-three-year follow-up study of rubella antibodies after immunization in a closed population, and serological response to revaccination

Twenty-six institutionalized children immunized with a Japanese rubella vaccine, Matsuba strain, have been observed for 23 years and the persistence of vaccine-induced rubella immunity documented. All vaccinees were shown to have seroconverted to rubella virus in a haemagglutination inhibition (HI) test, and the geometric mean titre (GMT) of rubella HI antibody rose to 2 5-8 months after vaccination (Ueda et al., Acta Paediatrica Japonica, Overseas Edition 1978, 20, 8-14). The GMT then declined gradually to 2 23 years after inoculation, except in four cases (15.4%) which had reverted to negative. However, three of the four maintained a rubella HI antibody titre of 1:4. Twelve of the 26 vaccinees were revaccinated 24 years after primary vaccination, and all ten cases having initial titres of < or = 1:16 demonstrated secondary responses. Rubella immunity induced by vaccination had persisted, so routine booster immunization did not seem necessary. However, a second immunization programme should be considered to achieve high antibody-positive rates and to protect against primary vaccine failure.

Molecular characterization of naturally occurring glycoprotein C-negative herpes simplex virus type 1

SummaryWe previously isolated glycoprotein C (gC)-negative herpes simplex virus type 1 (HSV-1) mutants, TN-1, TN-2 and TN-3, from a patient with recurrent herpetic keratitis at one-year intervals. In the present study, the molecular basis for the inability of these clinical isolates to express gC was examined. The nucleotide sequence of the gC gene of the TN-1 strain was compared with that of the HSV-1 KOS strain. In the open reading frame of the gC gene, there were 12 nucleotide differences between the TN-1 and KOS strains, seven of which led to amino acid substitutions. Importantly, one of them was the codon change from CAG for glutamine at position 280 to TAG for the amber termination codon. Accordingly, the TN-1 strain produced a truncated gC with a predicted molecular weight, which was secreted into the extracellular fluid. These results suggest that this amber mutation in the TN-gC gene results in a premature termination of gC translation and is the cause of the gC-negative phenotype of the TN strains. It is expected that these extremely rare HSV-1 strains will provide us with valuable information concerning the in vivo functions of gC, especially in ocular diseases.

Recurrent Herpetic Keratitis: Failure to Detect Herpes simplex Virus Infection Using the Syva MicroTrakTM HSV1/HSV2 Direct Specimen Identification/Typing Test

A 35-year-old man had developed recurrent herpetic keratitis characterized by dendritic keratitis at intervals of a year. We were able to culture cytopathic agents repeatedly from his lesions by inoculating Vero cells. The cultures yielded definitive evidence of a virus that caused a cytopathic effect within 3 days. However, these virus strains could not be identified as herpes simplex virus (HSV) in immunofluorescence assays using the Syva MicroTrak HSV1/HSV2 direct specimen identification/typing test. Rather they were identified as strains of HSV type 1 (HSV-1) on the basis of plaque morphology, neutralization tests, electron-microscopic examination and DNA restriction endonuclease analysis. Our results allow us to assume the existence of HSV-1 strains isolated clinically that are negative to analysis using the Syva Micro-Trak HSV1/HSV2 direct specimen identification/typing test.

Seroepidemiology of Herpes Simplex Virus Type 1 in Yanji, Jilin, China

Sera from 158 individuals in Yanji, Jilin, China, were tested for antibodies to herpes simplex virus type 1 (HSV‐1) by the passive hemagglutination method. Age‐specific incidence rates for antibodies to HSV‐1 were calculated. For sera from persons in the age group 10 years or less, the positive rate was 54% but in the age group higher than 10 years, it was more than 91% (P<0.01). In the part of China surveyed, primary HSV‐1 infection occurred in early generation before about age 10. In children, the positive rate in the Han race was significantly higher than that in the Korean race (P<0.05).

Pathogenicity of Glycoprotein C-Deficient Herpes Simplex Virus 1 Strain TN-1 Which Encodes Truncated Glycoprotein C

A clinical isolate of herpes simplex virus 1 (TN‐1) from a stromal keratitis patient was found to be defective in the glycoprotein C (gC) gene (UL44), thus resulting in the production of truncated gC upon infection. To study the pathogenetic role of truncated gC, we prepared a recombinant LTN‐8 derived from TN‐1 with deletions of the 1.5 kilobase pairs of the gC gene including the initiation codon. A penetration assay revealed LTN‐8 to be less efficient in its penetration ability than TN‐1, the laboratory strain KOS and RTN‐1‐20‐3, a recombinant derived from TN‐1 with the KOS gC gene. The penetration of LTN‐8 was facilitated by the addition of TN‐1‐infected culture medium. TN‐1 virus preparations had no hemagglutinating activity. However, the animals infected with TN‐1 did develop hemagglutination inhibition (HI) antibodies. The LTN‐8‐infected animals did not develop HI antibodies. The pathogenicity in BALB/c mice following either corneal, intraperitoneal or intracerebral inoculation did not significantly differ among TN‐1, RTN‐1‐20‐3 or LTN‐8. Our results indicate that truncated gC was sufficient for the induction of HI antibodies and was also able to facilitate penetration in vitro. Although truncated gC might be a virulence factor acting as a decoy, both truncated gC and intact gC had little effect on the outcome following intracerebral, intraperitoneal or corneal inoculation.