Isamu Tagaya

Epidemic of hand, foot and mouth disease associated with enterovirus 71 infection.

Viruses isolated from patients with hand, foot and mouth disease in widespread outbreaks in Japan in 1973 were identified as enterovirus 71. Although cases with aseptic meningitis were observed concurrently, the main clinical symptom associated with enterovirus 71 infection was hand, foot and mouth disease.

Comparative studies of several vaccinia virus strains by intrathalamic inoculation into cynomolgus monkeys.

SummaryFrom the comparative studies of the virulence of several vaccinia virus strains by intrathalamic inoculation into cynomolgus monkeys, the following results were observed. The CV1 virus was most virulent, the New York City Board of Health, Ikeda, EM63, and Lister viruses were slightly less virulent, and DIs and LC 16 viruses least virulent.The characteristic findings were widespread inflammatory lesions in the meninges and choroid plexus which were closely associated with the replication of vaccinia virus, and parenchymal lesions which might be referred to as encephalopathy in the deceased monkeys. Meningoencephalitis was, however, often recognized in the monkeys sacrificed at 14 days postinoculation and those dying late.

Studies on the early antigens induced by vaccinia virus.

Abstract Antisera directed against vaccinia-induced early antigen(s) detectable by immunofluorescence on the surface of infected cells (S-antigen) were prepared by immunizing rabbits with rabbit kidney cells infected with a conditional lethal mutant. Rabbit sera against soluble early antigen preparations from HeLa cells infected with the mutant were also reactive to the S-antigen. These sera did not stain cytoplasmic inclusions when infected cells were acetone-fixed. The reactivity of the antisera was not affected by extensive absorption of the sera with host cell antigens. Neither types of antisera neutralized vaccinia virus, but fixed complement when reacted with a homogenate of vaccinia-infected cells as well as with soluble early antigen preparations. Two precipitation bands were observed by immunodiffusion between these sera and a homogenate of vaccinia-infected CAM, which coalesced with a portion of several bands formed between a hyperimmune anti-vaccinia rabbit serum and the same antigen. The relationship between the S-antigen and the soluble early antigens was discussed.

Immunological relationship between herpes simplex virus and B virus

The cross neutralization was observed in both anti-HSV and anti-B virus immune sera. Cynomolgus monkeys having natural B virus antibody also showed a higher neutralizing activity to HSV. Some monkeys showed only HSV neutralizing antibody. Highly specific antiserum was prepared by immunizing guinea pigs or rabbits with heat-inactivated virus. These sera proved to be available to differentiate HSV and B virus isolates serologically.

Structural Polypeptides of Several Strains of Orthopoxvirus

Orthopoxviruses share common antigens detectable by serological techniques, although they differ biologically from each other. In the course of studies on the antigenic differences among vaccinia and some closely related viruses, analysis of structural polypeptides has been carried out and the results indicated that polypeptides of molecular weights of about 30,000 to 40,000 were characteristic for variola, vaccinia, monkeypox and cowpox viruses, although SDS-polyacrylamide gel electro-

Common antigen between coxsackievirus A 16 and enterovirus 71.

Cross immunofluorescence revealed that coxsackievirus A 16 (CA 16) shared a common antigen with enterovirus 71 (E 71). The cross reactivity of these two serotypes was also examined by complement fixation test with purified virus preparations fractionated by sucrose density gradient centrifugation and two peaks of antigenicity were detected, one being type‐specific and the other cross‐reacting. The common antigen was heat‐stable and attributable to empty capsids. Immunodiffusion also revealed the common antigen. Infants without antibody to E 71 developed complement fixing and precipitin antibody to E 71 after recovery from hand, foot and mouth disease caused by CA 16.

Seroepidemiology of Enterovirus 71 among Healthy Children near Tokyo

In 1973 an epidemic of hand, foot and mouth disease (HFMD) took place throughout Japan (4). We reported that this epidemic was associated with enterovirus 71 (E71) infection, which had not been known to cause a wide-spread outbreak of the disease (1). In order to know whether or not E71 was prevalent in Japan before this epidemic, we carried out a sero-survey on neutralizing-antibody against E71 among healthy children. Sera of healthy children, from zero to ten years of age, were collected in Takatsu area, Kawasaki City near Tokyo, every March from 1966 to 1973. The

A Comparison of Neurovirulence of Vaccinia Virus by Intrathalamic and/or Intracisternal Inoculations into Cynomolgus Monkeys

The authors have studied the virulence of several vaccinia virus strains by intrathalamic (i.t.) inoculation into cynomolgus monkeys for the purpose of analysing the pathogenesis of postvaccinial encephalopathy or encephalitis (1, 3). Before these studies, we performed a quantitative comparison of the neurovirulence in monkeys by i.t. and/or intracisternal (i.c.) inoculations with Lister strain as well as CV 1 strain of vaccinia virus. The reference Lister (calf lymph) vaccine and the CV 1 vaccine which was kindly provided from Dr. C.H. Kemp, University of Corolado, were grown in the chorioallantoic membrane (CAM) of 11 to 12 day eggs. The virus was purified. from CAM homogenates by fluorocarbon treatment and sucrose gradient centrifugation, and adjusted to 4 •~ 108 PFU/ml. Monkeys were inoculated intrathalamically and/or intracisternally with 0.5 ml each of serial 10-fold dilutions of the virus. Nine monkeys were used for each experiment and three monkeys for each dilution. The mortality of the monkeys inoculated with each virus strain and by the different inoculation routes, is summarized in Table 1. With the Lister srain the mortality of the monkeys inoculated intrathalamically was slightly higher than that by the i.c. route. Furthermore, there was no clear difference in the mortality between the i.t. inoculation and combination of both i.t. and i.c. routes. This led the authors to use i.t. inoculation only in further experiments as described elsewhere

Isolation of Cowpox Virus Clones Deficient in Production of Type A Inclusions: Relationship to the Production of Diffusible LS Antigen

Cowpox virus clones (A- clones) deficient in production of type A inclusions were isolated from two cowpox strains, Amsterdam and 53. These clones did not differ from their parents in major markers such as pock morphology in chorioallantoic membranes and pathogenicity in the rabbit skin. However, the LS antigens induced by A- clones developed precipitin lines in agar gel diffusion tests, while the antigens from their parents failed to precipitate. Immunofluorescence and agar gel diffusion tests revealed that antigens detectable by antisera against purified type A inclusions and LS antigens were closely related to each other. These findings suggest that the A- clones might be variants of cowpox virus which have lost the ability to assemble LS antigens into type A inclusions.

Orthopoxvirus Strains Defective in Surface Antigen Induction

Various strains of vaccinia, variola, whitepox, monkeypox and cowpox viruses were examined for their capacity to induce a specific early antigen detectable on the surface of infected cells. The Elstree strain of vaccinia, two strains of variola minor and white variants of cowpox and monkeypox viruses lacked the capacity to induce the antigen. Variation of the parent cowpox and monkeypox viruses to white variants was always accompanied by the loss of the antigen-inducing capacity.