Assessment of skin test with varicella-zoster virus antigen for predicting the risk of herpes zoster.

The Shozu Herpes Zoster (SHEZ) Study was designed to clarify the incidence of and predictive and immunological factors for herpes zoster in a defined community-based Japanese population. As part of this series, a total of 5683 residents aged ≥50 years received a varicella-zoster virus (VZV) skin test with VZV antigen, and 48 h later, the erythema and oedema were assessed by measuring the longest diameter. The diameters of both the erythema and oedema decreased with the increasing age of the subject. Sixty-three subjects contracted herpes zoster within a year after receiving the VZV skin test. Analysis of the herpes zoster incidence rate vs. the skin test reaction revealed that the shorter the diameter of erythema or oedema, the greater the likelihood of herpes zoster. These results demonstrated that the VZV skin test is an excellent surrogate marker for predicting the risk of herpes zoster.

Evaluation of immune responses to inactivated influenza vaccines prepared in embryonated chicken eggs and MDCK cells in a mouse model.

This study was initiated with the isolation of influenza A and B viruses from clinical throat swabs in both fertile chicken eggs (egg) and MDCK cells, which were used in subsequent vaccine production in the above two hosts. On the basis of haemagglutination-inhibiting (HI) tests, immune mouse sera from mice vaccinated with MDCK cell-derived vaccines revealed antigenic similarities among H3N2 or B viruses isolated in MDCK cells or eggs. Similarly, antiserum prepared by immunization with egg-derived H3N2 vaccine showed equivalent antigenicity between homologous and heterologous (MDCK cell-derived) viruses. In contrast, antigenicity of egg-derived B vaccines was differed somewhat from that of MDCK cell-derived vaccines, suggesting the occurrence of antigenic change due to passaging in eggs. The time-course of immune responses based on HI titres indicated that MDCK cell-derived vaccines elicited extremely high antibody levels. Also, it was evident that antibody production by MDCK cell-grown H3N2 vaccine was very similar to that of vaccine prepared from egg-grown viruses. These results were comparable to those of plaque neutralization tests, although antigenic differences between egg- and MDCK cell-derived challenge viruses were confirmed in the test with antiserum to MDCK cell-derived vaccine. Consistent with HI-antibody production, the immunogenicity of MDCK cell-derived B vaccine appeared to be low by plaque neutralization test, while immune responses in mice which received egg-derived vaccines were significantly higher than that of the former. Furthermore, immune responses confirmed in mice immunized with B virus vaccines prepared in eggs revealed slight antigenic differences between two viruses derived from their respective hosts. Nevertheless, through evaluation of immune responses, MDCK cell-derived influenza vaccines may be useful when weak immunogenicity of B virus vaccine is improved.

A novel strain, B/Gifu/2/73, differs from other influenza B viruses in the receptor binding specificities toward sialo-sugar chain linkage.

We reported in a previous paper (1. Xu et al, J. Biochem., 115, 202-207, 1994) that every human influenza B virus isolate determined, including B/Lee/40, B/Setagaya/3/56, B/Tokyo/7/66, B/Kagoshima/1/68, B/Kanagawa/3/76, B/Ibaraki/2/85, B/Yamagata/16/88, and B/Bangkok/163/90, restrictively recognizes lacto-series gangliosides containing Neu5Ac alpha 2-6Gal linkage. We found in this study a novel strain, B/Gifu/2/73, that showed remarkable receptor binding specificities to both Neu5Ac alpha 2-3 Gal and Neu5Ac alpha 2-6Gal linkages of lacto-series gangliosides. The amino acid sequence of the hemagglutinin (HA) in strain B/Gifu/2/73 was compared with that of B/Lee/40, B/Ibaraki/2/85, B/Yamagata/16/88, and B/Bangkok/163/90. Substitution of His116, Ala121, Arg141, Pro211, His253, and His271 in the HA1 subunit of strain B/Gifu/2/73 for Asn116, Thr121, Gly141, Gln211, Gln253, and Gln271 in the HA1 of the four strains above was found, indicating that these amino acid changes in the HA1 of B/Gifu/2/73 may play an important role in recognition of Neu5Ac alpha 2-3Gal and Neu5Ac alpha 2-6Gal linkages in the receptor sialo-sugar chains.

Enzyme-linked immunosorbent assay of influenza specific IgA antibody in nasal mucus.

An enzyme-linked immunosorbent assay of influenza HA specific IgA antibody in nasal mucus is described. This assay is very sensitive and only a minute quantity of nasal mucus is required.