[Seroepidemiology of alphaherpesviruses]

The seroepidemiology of herpes simplex virus (HSV) type-1 and -2 was studied in different Japanese populations, by applying HSV gG1 and gG2 type-specific antibody assays. HSV-1 infections correlated mostly with age and was widely prevalent among subjects over 40 years old. HSV-2 prevalence varied greatly among subgroups defined by sexual activity and were associated with risk behaviors, from 80% among prostitutes to 7% among pregnant women. Since HSV-1 infection during childhood has been decreasing, primary genital HSV-1 or HSV-2 infection, with its higher frequency of clinical manifestations, will become more important. In contrast, antibody prevalence to varicella-zoster virus has been constantly high in children, with no tendency to change in seroepidemiology of VZV infections so far.

Changes in prevalence of herpes simplex virus type 1 and 2 antibodies from 1973 to 1993 in the rural districts of Japan

Using the gG-capture ELISA, changes in the seroprevalence of HSV-1 and HSV-2 from 1973 to 1993 were studied for 614 sera collected from general adults living in rural Japan. The HSV-1 seroprevalence for men and women decreased from 75.3 and 80.6% in 1973 to 54.4 and 59.6%, respectively, in 1993. The HSV-2 seroprevalence also decreased from 10.2 and 9.9% in 1973 to 1.8 and 1.2%, respectively, in 1993. Although the decrease in HSV-2 prevalence seemed to be correlated with the general decrease of sexually transmitted diseases in Japan since the 1950s, these findings should not be interpreted as typical, as HSV-2 infections are particularly known to distribute unevenly among populations, according to sexual activity and cohorts.

Evaluation of an enzyme-linked immunosorbent assay based on binding inhibition for type-specific quantification of poliovirus neutralization-relevant antibodies

To detect neutralization-relevant antibodies against 3 types of poliovirus (PV) without using tissue cultures and live viruses, an enzyme-linked immunosorbent assay (ELISA) based on monoclonal antibody-binding inhibition was evaluated using sera from 80 vaccinated Japanese children and 60 Pakistani poliomyelitis patients. Compared with the neutralization test, the sensitivity of the inhibition ELISA was 100% (111/111) for detection of anti-PV1 antibody, 98.3% (118/120) for anti-PV2, and 96.5% (82/85) for anti-PV3, and the specificity was 93.1% (27/29), 100% (20/20), and 92.7% (51/55), respectively. Thus, the inhibition ELISA showed excellent potential as a seroepidemiologic tool in both vaccinated and naturally-infected populations.

Molecular and serological characterization of adenovirus genome type 7h isolated in Japan

In 1996, three adenovirus type 7 (Ad7) strains were isolated from children with fever and upper respiratory diseases in Japan. Restriction endonucleases (REs) analysis and PCR amplification of the E3 7.7 kDa ORF revealed that these strains were genotype Ad7h and closely related to an Argentine Ad7h strain, which has been reported to be highly virulent and so far predominant only in South America. These strains showed weak cross-neutralizing activity and specific haemagglutination-inhibition activity to Ad3 antiserum. The present findings suggest that Ad7h in South America has spread to other parts of the world. Since the seroprevalence to Ad7 in the current Japanese population is very low due to the absence of Ad7 circulation in Japan for decades, Ad7 outbreak as a typical case of re-emerging infectious diseases is a cause for serious concern.

An epidemiologic study of herpes simplex virus type 1 and 2 infection in Japan based on type-specific serological assays

A seroepidemiologic study of herpes simplex virus type 1 (HSV-1) and 2 (HSV-2) was performed on Japanese adults. Serum samples collected between 1985-9 from a total of 536 healthy adults, female prostitutes, males with sexually transmitted diseases (STD), homosexual men, and pregnant women were studied by immunodot assays using HSV type-specific antigens, glycoproteins G (gG1 and gG2). HSV-1 infections correlated mostly with age and was widely prevalent among subjects < 40 years. HSV-2 prevalence varied greatly among subgroups defined by sexual activity and was associated with risk behaviours for prostitution, infection with STD, and homosexual activity. HSV-2 seroprevalence was highest among prostitutes (80%), lowest among pregnant women (7%), and intermediate in STD patients (23%) and homosexuals (24%). Because HSV-1 infection during childhood has been decreasing, primary genital HSV-2 infection, with its higher frequency of clinical manifestations, will become a greater burden to the public health in Japan.

Prevalence of herpes simplex virus type 1- and 2- specific antibodies among the acute, recurrent, and provoked types of female genital herpes

Sixty-eight sera from the acute, recurrent, and provoked types of female genital herpes were compared for the seroprevalence of herpes simplex virus (HSV) types 1 and 2 by immunodot assay using HSV glycoprotein G. In the HSV-1-isolated patients, no HSV-2 antibodies were detected, whereas in the HSV-2-isolated patients, HSV-1 seroprevalence was 9% for the acute type, 89% for the provoked type (P < 0.005), and 55% for the recurrent type (P < 0.05). The natural history of female genital herpes and the possible protective role of pre-existing antibodies in preventing the acquisition or clinical manifestation of a subsequent HSV infection are discussed.

Detection of herpes simplex virus type-specific antibodies by an enzyme-linked immunosorbent assay based on glycoprotein G

In order to develop a simple and quantitative method to detect herpes simplex virus (HSV) type-specific antibodies, the usefulness of an enzyme-linked immunosorbent assay (ELISA) using HSV glycoprotein G (gG) captured on a plate by monoclonal antibodies as antigen was studied. The gG1- and gG2-specific IgG antibody activities were measured by the ELISA for 54 sera which had been collected from culture-proven genital herpes patients and pre-characterized by an immunodot assay using purified gG antigens. Thirty control sera without antibodies against the HSV whole antigens were also included. In comparison with the immunodot assay as standard, the sensitivities of the ELISA were 88.9% (32/36) for HSV-1 antibody and 89.2% (33/37) for HSV-2 antibody and the specificities were both 100%. Sera taken within a few months after primary infection tended to give false negative results. The HSV type-specific ELISA based on easy-to-prepare gG antigens might be useful to help improve the serological assessment of HSV infections.

Differentiation of primary from nonprimary genital herpes infections by a herpes simplex virus-specific immunoglobulin G avidity assay

An immunoglobulin G (IgG) antibody avidity assay which uses protein-denaturing agents and a modification of an enzyme-linked immunosorbent assay have been investigated for their usefulness in distinguishing primary genital herpes simplex virus (HSV) infections from nonprimary infections. Forty-nine serum specimens from patients with primary, recurrent, and nonprimary first-episode genital herpes were studied. The clearest separation was obtained with 6 M urea treatment, giving mean avidity indices of 0.398 for sera < or = 100 days after the infection and 0.879 for sera > 100 days after the infection (P < 0.001). No significant difference in avidity indices was observed between the recurrent and nonprimary first-episode infections. Determination of the avidity of HSV-specific IgG will improve the diagnostic potential of HSV serology.

Herpes simplex virus-specific IgM, IgA and IgG subclass antibody responses in primary and nonprimary genital herpes patients

To clarify the humoral immunity in herpes simplex virus (HSV) infection, HSV-specific IgM, IgA and IgG subclass antibody responses were studied in patients with genital herpes: 17 primary, 13 recurrent and 6 nonprimary first episode. A total of 181 serum samples serially collected from the patients, 5 per patient until 213 days after the onset of disease (on average), were analyzed by an enzyme-linked immunosorbent assay. IgG1, IgG3 and IgA were detected in all patients with primary and nonprimary infections, whereas IgG4 was detected in 74% of only those with nonprimary infections and IgG2 was detected in none. IgM was detected in 100% of the patients with primary infections, but also in 68% of those with nonprimary infections. IgA showed a peak similar to that of IgM in patients with primary infections. No significant difference was observed in the detection rate or pattern of antibody responses between the recurrent and nonprimary first episode infections, nor between the HSV-1 and HSV-2 infections. These findings may be useful to improve the diagnostic potential of HSV serology.

Class-specific antibody response in acyclovir-treated and adenine arabinoside-treated patients with primary genital herpes simplex virus infection

Herpes simplex virus (HSV) class-specific antibody responses after primary genital herpes infection were evaluated with an enzyme-linked immunosorbent assay (ELISA) in 16 patients treated with acyclovir (ACV), given orally, and 17 patients treated with adenine arabinoside (Ara-A), given topically. ACV significantly suppressed the levels of IgM, IgA, and IgG. In the ACV-treated patients, IgM and IgG were not detected in 4 of the 16 and in 1 of the 16 patients, respectively. We must take into account this suppressive effect of ACV on antibody responses, especially on the IgM response, when serodiagnosis of HSV infection is made.

Adenovirus surveillance, 1982-1993, Japan. A report of the National Epidemiological Surveillance of Infectious Agents in Japan

The Infectious Agents Surveillance Center, the National Institute of Health, Japan, received 17,265 reports from 1982 to 1993 on cases from whom adenovirus was isolated or detected; 85% from 57 public health institutes and the other 15% from two national hospitals and two commercial diagnostic laboratories. The followings were found. Three major diseases caused by adenovirus were upper respiratory tract infection, gastroenteritis, and conjunctivitis. Patients of upper respiratory tract infection numbered 6,837 (40% of all patients due to adenovirus), the identified serotypes being in order of frequency types 3, 2, 1, and 5. Those of gastroenteritis numbered 1,636 (9.5%). From 40% of the gastroenteritis patients, adenovirus was detected by electron microscopy or immunochemical methods without cultivation. From the remaining 60%, virus was isolated in tissue culture; the serotypes of the isolates resembled those causing upper respiratory tract infection. Patients of conjunctivitis numbered 3,437 (20%), the frequency being in order of types 3, 4, 8, 37, and 19. Conjunctivitis due to types 3 and 4 prevailed every summer; type 3 was isolated often from children with pharyngo-conjunctival fever and the other four types were mostly from adults with epidemic keratoconjunctivitis. Type 3 had a unique feature not seen in other types: it was most frequently isolated, causing upper respiratory tract infection, gastroenteritis, conjunctivitis, and pharyngo-conjunctival fever. Reports on isolation of type 7, which has been reported to cause severe pneumonia in many other countries, were as few as 28 (0.2%).

[Type-specificity of serum antibodies from genital herpes patients as determined by an enzyme-linked immunosorbent assay using HSV-infected cells as antigens]

Type-specificity of serum antibodies from genital herpes patients was determined by an enzyme-linked immunosorbent assay (ELISA) using antigens extracted from herpes simplex virus (HSV) type 1- and 2-infected cells. Sixty-three of HSV type-known panel sera, which had been typed by HSV glycoprotein G-specific immunodot analysis, consisted of 3 groups; group I (25 sera; gG-1 antibody- and HSV-1 isolation-positive), group II (19 sera; gG-2 antibody- and HSV-2 isolation-positive) and group III (19 sera; gG-1 and gG-2 antibodies- and HSV-2 isolation-positive), were assayed for IgM, IgA, IgG1 and IgG3 antibody activities (optical densities) against HSV-1- as well as HSV-2-infected cell antigens. IgG antibodies of these 3 groups showed 2 different patterns of reactivities. The group II sera reacted with the two antigens to the same extent and could be differentiated from other 2 groups. The latter 2 groups were difficult to differentiate because of similar reaction patterns showing higher reactivities to HSV-1 antigen. In contrast, type-specificity was not observed in IgM antibody activities. The higher reactivities of IgG antibody to HSV-1 antigen than to HSV-2 antigen in the group III sera indicate the "original antigenic sin" phenomenon, i.e.; memory B cells produced in prior infection with HSV-1 were activated by cross-reactive antigens of HSV-2 which infected secondarily. To presume the type of infected HSV from serum antibody reactivities was difficult as long as HSV-infected cells were used as antigens in ELISA.

Epidemics of aseptic meningitis due to echovirus 30 in Japan. A report of the National Epidemiological Surveillance of Infectious Agents in Japan

Two rages of epidemic of aseptic meningitis (AM) due to echovirus 30 (E30) in Japan were analyzed with respect to two sources of information, AM incidence and E30 isolation, both gathered through the National Epidemiological Surveillance of Infectious Diseases. The first E30 epidemic spread throughout Japan in 1983 and ceased within the year. The second epidemic, starting in 1989, continued for the three successive years, and in the last year, 1991, the total E30 reports numbered 4,061, the largest number of a single virus type ever reported. Although the epidemic showed temporal and geographical shift and lasted for one or two years in some areas, most laboratories reported the largest number of E30 isolation in 1991. Among E30-yielding cases with clinical information during 1982-1992, the associating frequency with AM was as high as 82.5%. Other central nervous system involvements such as encephalitis, myelitis, encephalomyelitis and/or paralysis were reported in 36 E30-yielding cases and their monthly and age distributions were different from those of AM cases. The proportion of such disease among E30-yielding cases (0.60%) was close to that of other enteroviruses (0.56%). During the epidemics, E30 was isolated more frequently from cerebrospinal fluid than was E4 or E9 which prevailed coincidentally. E30 was most frequently isolated from cases of 4-7 years of age, sharing the common characteristic pattern of age distribution with other enteroviral meningitis. E30-yielding cases, however, involved a large number of older age groups than those of other enterovirus infections, and this tendency was the most pronounced in the first epidemic year, 1983. The contribution of these E30 epidemics on the yearly trend of clinically reported AM incidence and on the shift of its age distribution was also analyzed.

Diagnosis of genital herpes by polymerase chain reaction amplification

A new polymerase chain reaction (PCR) method employing type-specific primers and probes was applied to 114 clinical specimens obtained from 58 female patients with genital lesions or who had a history of genital herpes. Ten and 15 specimens, respectively, were positive for herpes simplex virus (HSV)-1 and HSV-2 by cell culture. All of 10 culture-confirmed HSV-1 cases and 11 of 15 (73%) culture-confirmed HSV-2 cases were identified by PCR. Although there were several cases with discrepancy between cell culture and PCR for HSV-2, the results suggest that this PCR procedure could be applied to clinical specimens from the female genital tract.

[Detection of polymeric IgA antibody to herpes simplex virus by pretreatment of sera with Streptococcus pyogenes--its application to diagnosis of primary infection]

In 17 patients of genital herpes virus infections, herpes simplex virus (HSV)-specific IgA antibody responses were analyzed using an enzyme-linked immunosorbent assay (ELISA) and the absorption of sera with Streptococcus pyogenes, AW43 and AR1, which bind monomeric IgA (m-IgA) and IgG antibodies, respectively. The ratio of polymeric IgA (p-IgA) to total IgA was calculated from the formula, the p-IgA index = IgA activity after absorption/IgA activity before absorption. In early-convalescent-phase sera from primary cases, the p-IgA indices were 0.5-0.9, whereas in recurrent or provoked cases, they were lower than 0.2. There results indicate that the p-IgA index may be useful for rapid and simple differentiation of primary from non-primary HSV infections.

Detection of human antibody against the human papillomavirus type 16 E7 protein

We examined 500 human sera for the presence of antibody against the human papillomavirus type 16 E7 protein by enzyme-linked immunosorbent assay with bacterially expressed fusion protein lac-E7, and by radioimmunoprecipitation and immunofluorescence assays with the E7 protein expressed in monkey COS-1 cells. The anti-E7 antibody was detectable in 6 out of 54 cases of cervical carcinoma, but in none of the others, including patients with other gynecologic cancers, those with sexually transmitted diseases, and healthy adults. The data indicate that expression of the E7 protein is closely related to cervical carcinoma.

Detection of HTLV-I antigen in peripheral and cord blood lymphocytes from carrier mothers

Vertical transmission of human T-cell lymphotropic virus type-I (HTLV-I) from an antibody-positive carrier mother to her infant has been reported, but it is not clear when and by what route such transmission occurs. Peripheral blood and cord blood lymphocytes from 40 antibody-positive carrier mothers were cultured for 2 months and HTLV-I antigen was sought by indirect immunofluorescence. Viral antigen was detected in 28 (70%) samples of peripheral blood lymphocytes and in 2 of cord blood lymphocytes, both from mothers positive for antigen in peripheral blood. From these data it is estimated that transplacental infection occurs at a rate of about 7%.

Differentiation of primary from nonprimary genital herpesvirus infections by detection of polymeric immunoglobulin A activity

We analyzed antibody responses to herpes simplex virus (HSV) in 18 patients by using sucrose gradient centrifugation and an enzyme-linked immunosorbent assay for antibody determination. We found that the HSV-specific immunoglobulin A (IgA) antibody in early-convalescent-phase serum specimens from all of 8 primary cases consisted solely of polymeric forms, whereas in all 10 nonprimary cases, the major component was monomeric. These results indicate that the ratio of polymeric IgA to monomeric IgA antibody activity may be useful for differentiating primary from nonprimary HSV infections.