Immune Adherence Hemagglutination Research Articles

Anti-varicella-zoster virus antibody titers and seroprotection status from before the first dose of varicella vaccination to before entering elementary school in one region in Japan.

We aimed to examine changes in anti-varicella-zoster virus (VZV) antibody titers and seroprotection status from before the first dose of vaccination to before 7years old entering elementary school in children who received the routine two-dose varicella vaccination. Participants were 37 healthy children who received the routine two-dose varicella vaccination at our hospital. A total of five serum samples per child were collected immediately before and 4-6weeks after each dose of the vaccination and in the year before entry to elementary school. We measured anti-VZV antibody titers by immune adherence hemagglutination (IAHA) method and glycoprotein-based enzyme-linked immunosorbent assay (gpELISA). A positive antibody titer and the seroprotection level were set as ≥2-fold and ≥16-fold, respectively, for IAHA antibody and as ≥50 units and ≥105 units, respectively, for gpELISA-IgG antibody. The rates of IAHA antibody positivity in the five samples (in order of collection) were 0%, 65%, 38%, 100%, and 59%, and the rates of seroprotection were 0%, 43%, 8%, 100%, and 43%. The rates of gpELISA-IgG antibody positivity were 8%, 81%, 89%, 100%, and 100%, and the rates of seroprotection were 5%, 54%, 70%, 100%, and 89%. The mean IAHA antibody titer and mean gpELISA-IgG antibody titer before entering elementary school were both lower than the respective titers obtained after the second vaccination (both p<0.01). Routine two-dose varicella vaccination leads to good antibody production, but titers of acquired antibodies decrease before children enter elementary school.

Sensitivity and specificity of different antibody tests for detecting varicella-zoster virus

IntroductionAntibody tests for detecting varicella-zoster virus include the fluorescent-antibody-to-membrane-antigen (FAMA) assay, immune adherence hemagglutination assay (IAHA), enzyme immunoassay (EIA), and the glycoprotein-based enzyme-linked immunosorbent assay (gpELISA). Although FAMA and gpELISA are highly sensitive, FAMA is not available commercially. Therefore, this study was performed to compare potential high-sensitivity tests with commercially available tests. MethodsFour antibody tests, FAMA, gpELISA, EIA, and IAHA, were performed using sera collected from 32 children aged 7 months–10 years. Using FAMA as a reference, the sensitivity and specificity of gpELISA, EIA, and IAHA were assessed. Subsequently, using gpELISA as a reference, the positive agreement rate of EIA and IAHA was assessed. ResultsOn a reference scale with FAMA set at 100%, the sensitivity and specificity of the antibody tests were as follows: gpELISA, 67% and 100%; EIA, 67% and 100%; and IAHA, 47% and 100%, respectively. The positive agreement rates of EIA and IAHA relative to gpELISA were 86% and 64%, respectively.Conclusions: gpELISA had a lower positive rate than did FAMA, and showed comparable sensitivity to that of EIA.

Results of Booster Vaccination in Children with Primary Vaccine Failure after Initial Varicella Vaccination

In October 2014, the varicella vaccination policy in Japan was changed from a single voluntary inoculation to two routine inoculations. This paper reports the results of booster vaccination in children who did not show seroconversion after initial vaccination (i.e., primary vaccine failure : PVF) over a 7-year period prior to the introduction of routine varicella vaccination. Between November 2007 and May 2014, 273 healthy children aged between 1.1 and 14.5 years (median : 1.7 years) underwent varicella vaccination. Before and 4 to 6 weeks after vaccination, the antibody titers were measured using an immune adherence hemagglutination (IAHA) assay and a glycoprotein-based enzyme-linked immunosorbent assay (gpELISA). In addition, side reactions were examined during the four-week period after vaccination. Children who did not show IAHA seroconversion (PVF) were recommended to receive a booster vaccination, and the measurement of antibody titers and an assessment of side reactions were performed after the booster dose. In May 2015, a questionnaire was mailed to each of the 273 participants to investigate whether they had developed varicella and/or herpes zoster after vaccination. After initial vaccination, the IAHA seroconversion rate was 75% and the mean antibody titer (Log2) with seroconversion was 4.7, while the gpELISA seroconversion rate was 84% and the mean antibody titer (Log10) with seroconversion was 2.4. Among children with PVF, 54 received booster vaccination within 81 to 714 days (median : 139 days) after the initial vaccination. After booster vaccination, the IAHA seroconversion rate was 98% and the mean antibody titer (Log2) with seroconversion was 5.8. Both the seroconversion rate and the antibody titer were higher compared with the values after the initial vaccination (p < 0.01). After booster vaccination, the gpELISA seropositive rate was 100% and the mean positive antibody titer (Log 10) was 3.6 ; similar results were obtained for the IAHA assay, with a significantly higher, antibody response than that after the initial vaccination (p < 0.01). Side reactions were generally minor, including fever (≥ 37.5 degrees C), rash at the injection site, and rash at other sites. There were no significant differences in the incidences of side reactions between the initial and booster vaccinations. A total of 185 participants responded to the questionnaire (response rate : 68%), and the period between receiving the initial vaccination and their response to the questionnaire ranged from 1.0 to 7.5 years (median : 4.0 years). The prevalence of breakthrough varicella after the initial vaccination was 17% among seroconverters who did not receive booster vaccination and 14% among non-seroconverters who received booster vaccination, showing no significant difference between the two groups. In conclusion, there are no safety issues regarding the administration of a booster vaccination to children with PVF after an initial varicella vaccination, and,a good antibody response can be expected.

Evaluation of varicella zoster virus-specific cell-mediated immunity by using an interferon-γ enzyme-linked immunosorbent assay

BackgroundAdministration of the varicella vaccine induces both varicella-zoster virus (VZV)-specific humoral and cell-mediated immunity (CMI). ObjectiveTo assess VZV-CMI, we developed an interferon γ enzyme-linked immunosorbent assay (IFN-γ ELISA) that measures the quantity of total IFN-γ in culture supernatants of human peripheral blood mononuclear cells. Study designWe evaluated this method by comparing the pre- and post-vaccination immune response in peripheral blood mononuclear cells of 30 healthy children who were administered an initial varicella vaccination at Konan Kosei hospital. ResultsIFN-γ ELISA showed well-validated results; CMI was not detectable pre-immunization but became detectable post-immunization. Seroconversion was detected in 92.6% of subjects by the immune adherence hemagglutination test; however, half of the subjects did not display an increase in CMI levels. We also compared the incidence of breakthrough varicella and herpes zoster development between CMI post-positive and post-negative vaccinees at 1–2years after the last VZV vaccination. Eight subjects had a history of varicella or herpes zoster exposure post-VZV vaccination. Two of them with post-negative CMI contracted breakthrough varicella 15–16months after the last vaccination, even though they had sufficient VZV-specific antibody levels to be considered seropositive and seroprotected. Conversely, the others with post-positive CMI did not contract breakthrough varicella, despite experiencing extensive VZV exposure through casual contact with playmates and family. ConclusionsThe CMI data generated by this IFN-γ ELISA may accurately reflect real-world immune status, and CMI may be closely related to immunoprotection against breakthrough varicella development.

水痘ワクチンの初回接種後 3～5 年における追加接種の免疫原性

Additional varicella vaccination was carried out targeting 16 subjects who had immune adherence hemagglutination (IAHA) seroconversion following the initial varicella vaccination and did not contract breakthrough varicella after the initial vaccination. The median ages at the initial and additional vaccination were 2.1 (1.1-6.9) years old and 6.1 (4.4-10.5) years old, respectively. The mean interval between the initial and additional vaccination was 4.0 (3.2-5.2) years. IAHA and glycoprotein-based enzyme-linked immunosorbent assay (gpELISA) antibody titers were measured just before and 4-6 weeks after the additional vaccination. Side reaction was surveyed at four weeks after the additional vaccination, and compared with the results at the initial vaccination. IAHA and gpELISA seroconversion rates at the initial vaccination were 100% and 88% respectively. Prior to the additional vaccination, IAHA antibody titers significantly decreased in 50% of the subjects, and became negative in 38% of the subjects. On the other hand, a significant increase in IAHA antibody titers was observed in 25% of the subjects, and this is assumed to be the result of a subclinical infection after the initial vaccination. The positive rate of both antibodies after the additional vaccination was 100%, the mean IAHA antibody titer (Log2) after the initial/additional vaccination in seropositive subjects was 4.6/6.5, and the mean gpELISA antibody titer (Log10) was 2.3/4.0. The mean IAHA and gpELISA antibody titers were higher after the additional vaccination than after the initial vaccination (p < 0.01, p < 0.01). This is considered to be the booster effect due to the additional vaccination. At 0-2 days after the additional vaccination, a rash at the injection site was observed in 56% of the subjects, higher than the incidence after the initial vaccination (13%) (p < 0.05), but no severe systemic side reactions were observed at either the initial or the additional vaccination. In conclusion, an additional varicella vaccination 3-5 years after the initial vaccination is thought to have greater immunogenicity and is considered effective.

Nosocomial transmission of varicella to a healthcare provider positive for anti-varicella zoster virus antibodies: nonprotective positivity with an immune adherence hemagglutination assay

A 24-year-old male healthcare provider, having attended a varicella patient 2weeks before, developed varicella himself. He had shown a positive result for anti-VZV antibodies measured with an immune adherence hemagglutination assay (1:4) 1year before. The present case shows that a positive result with this assay does not necessarily indicate protection against VZV infection.

Relationship between Preexisting Anti-Varicella-Zoster Virus (VZV) Antibody and Clinical VZV Reactivation in Hematopoietic Stem Cell Transplantation Recipients

Reactivation of latent varicella-zoster virus (VZV), presenting as localized zoster or as disseminated infection, is a common and potentially serious complication in hematopoietic stem cell transplantation (HSCT) recipients. We retrospectively studied anti-VZV immunoglobulin G titers by the immune adherence hemagglutination method after HSCT and also studied VZV DNA by real-time PCR during clinical VZV reactivation using cryopreserved serum samples. No significant difference was found between anti-VZV titers in 13 patients with VZV infection (localized zoster in 11 patients and disseminated zoster in 2 patients) and in 13 subjects without VZV infection at each time point after HSCT. Preexisting anti-VZV titers of disseminated zoster cases tended to be lower than those of localized zoster cases (P=0.10). Serum VZV DNA copy numbers at the onset of disseminated zoster cases tended to be higher than those of localized zoster cases (P=0.09). A strong inverse correlation was found between preexisting anti-VZV titer and serum VZV DNA at onset (r=-0.90, P=0.006). In HSCT recipients, preexisting antibody does not prevent the development of VZV reactivation but may contribute to decreased viral load at onset, resulting in a mild clinical course.

Experience with live attenuated varicella vaccine (Oka strain) in healthy Japanese subjects; 10-year survey at pediatric clinic

Live attenuated varicella vaccine (Oka strain, Biken Institute, Osaka, Japan) was administered to 973 healthy individuals over a 10-year period (1987–1997) at the pediatric clinic of Showa Hospital in Japan. We evaluated the relevant serological and clinical data, which were collected by questionnaire. Seroconversion by the immune adherence hemagglutination method was documented in 94% (805/860) of the initially seronegative subjects. Of the initially seropositive subjects, 56% (63/113) showed enhancement of antibody after vaccination. Reactions to the vaccine were generally insignificant, except for a rash at the injection site, seen in the first 3 days post-administration in 17% (41/241) of the recently vaccinated subjects. In March 1998, we conducted a survey of 559 of the initially seronegative subjects who had received the vaccine 0.6–10.8 (mean 5.4) years earlier. Of these subjects, 21% (119/559) contracted breakthrough varicella. However, their symptoms were milder than those caused by natural varicella seen in unvaccinated children. Seroconversion was demonstrated in 92% (109/119) of these cases. The incidence of breakthrough disease decreased with a rise in postvaccination antibody titer to ≧32. Four of the subjects (0.7% of 559) developed herpes zoster following vaccination, two of whom had earlier exhibited breakthrough varicella. Lesions in one case of zoster, without breakthrough varicella, appeared on the cervical dermatome at the injection site. The vaccine was safe and effective. However, there was a relatively high incidence of rash at the injection site with certain lot numbers used in recent years which warrants investigation.

Serum Concentration of Circulating Immune Complexes in Cats Infected with Feline Immunodeficiency Virus Detected by Immune Adherence Hemagglutination Method.

Circulating immune complexes (CIC) in the sera from 45 clinically healthy cats and 23 feline immunodeficiency virus (FIV) infected cats were measured by an immune adherence hemagglutination (IAHA) method. The level of CIC in the sera from FIV sera-negative healthy cats was 47.2 +/- 47.3 micrograms/ml when expressed as heat aggregated feline IgG equivalent value in IAHA reactivity. On the other hand, the level of CIC in the sera from FIV infected cats was 757.4 +/- 910.5 micrograms/ml, which was significantly higher than that of healthy ones. CIC levels of 11 symptomatic cats and 12 asymptomatic ones were 837.8 +/- 1138.2 micrograms/ml and 683.0 +/- 684.2 micrograms/ml, respectively. These results showed that IAHA method was reliable to detect CIC levels of cat sera and that CIC levels in the sera of cats infected with FIV were higher than those of healthy ones.

Detection of circulating immune complexes in dog sera by immune adherence hemagglutination method.

Circulating immune complexes (CIC) in the sera from 102 clinically healthy dogs and from 16 Dirofilaria immitis (D. immitis) infected dogs were measured by the immune adherence hemagglutination (IAHA) method. The level of CIC in the sera from healthy dogs was 28.2 +/- 29.1 micrograms/ml. There was no significant difference in the levels of CIC regarding sexes or ages. On the other hand, the level of CIC in the sera from D. immitis infected dogs was 230.3 +/- 117.1 micrograms/ml, which was significantly (p < 0.01) higher than that of healthy dogs. The results of this study confirm that IAHA method is one of the reliable means of detecting and/or diagnosing immune complex mediated diseases in dogs.

Does reduced erythrocyte C3b receptor (CR1) activity contribute to the pathogenesis of yersinia triggered reactive arthritis?

Erythrocyte C3b receptor (CR1) activity was measured in 27 patients with yersinia triggered reactive arthritis and in 151 control subjects, including 36 patients with uncomplicated yersiniosis and 115 healthy subjects. CR1 was measured by the immune adherence haemagglutination method. Patients with yersinia triggered reactive arthritis had reduced levels of CR1 compared with the controls. This difference was mainly due to the finding that five out of six HLA B27 negative patients with arthritis had decreased CR1 activity. Such a quantitative difference may contribute to the pathogenesis of reactive arthritis by affecting the clearance of immune complexes.

C群ロタウイルスの疫学的研究

By electron microscopy survey of acute gastroenteritis of children in Matsuyama, rotaviruses were detected in 561 of 2479 fecal samples obtained between October, 1984 and September, 1988, in which 60 atypical and 259 typical rotaviruses, so far tested, were detected by polyacrylamide gel electrophoresis (PAGE) of viral RNA. Out of 60 atypical rotaviruses, 5 were observed in 1985, 7 in 1986, none in 1987 and 48 in 1988. These atypical rotaviruses were morphologically indistinguishable from typical ones and showed very similar RNA migration patterns of PAGE to those of group C rotavirus. Furthermore, one atypical virus (86-542) reacted with antiserum against a porcine group C rotavirus in immune electron microscopy, while it did not react with anti-group A rotavirus serum. On the other hand, hyperimmune guinea pig antiserum against 86-542 reacted with a couple of atypical rotavirus including viruses isolated in 1988, so far tested, but did not react with any of the typical viruses. These findings showed that atypical rotaviruses which were endemic in Matsuyama city in 1988 were defined as group C rotavirus. Moreover, these group C rotaviruses showed two kind of RNA migration patterns in PAGE, which clearly discriminated the virus were isolated before and after 1987. Epidemiological features of group C rotavirus were as follows. Children from whom group C rotavirus was isolated were older than those from of whom group A rotavirus was isolated. The epidemic season was in February through April, compared to December through March in group A virus. Retrospective seroepidemiological study by immune adherence hemagglutination test (IAHA) using the purified 86-542 virus as antigen indicated that 15 of 78 sera of children obtained in 1971 already possessed IAHA antibody against group C rotavirus.

VARICELLA-ZOSTER VIRUS PREVALENCE IN JAPAN: NO SIGNIFICANT CHANGE IN A DECADE

A seroepidemiologic time-comparison study was conducted to evaluate changes in IgG antibody to varicella-zoster virus (VZV) and to determine VZV prevalence in Japan with randomly collected serum samples from two healthy Japanese populations: 1973 (n = 670) vs. 1984 (n = 677). Enzyme-linked immunosorbent assay (ELISA) was found to be superior to the immune adherence hemagglutination test (IAHA) especially for detecting seropositivity in adults. Serologic results showed essentially no significant difference between the 1973 and the 1984 age-specific prevalences; with the exception of a slightly lower prevalence in the 5-year-old age group in 1973 than that in 1984. In general, the age-specific prevalence was lowest in the 1-year-old group (mean 11%) and increased in a linear fashion until age 9 (mean 82.9%); prevalence continued to increase slowly after age 9 and plateaued at 100% for ages greater than or equal to 25-29.

Complement receptor 1 (CR1) on erythrocytes of patients with systemic lupus erythematosus.

Ninety-five (85%) of the 112 Japanese patients with systemic lupus erythematosus (SLE) were negative for the complement receptor 1 (CR1) activities on erythrocytes, while 770 (91%) of the 847 normal subjects were positive for CR1, as determined by immune-adherence hemagglutination. Pedigree analyses of the normal population suggested that the phenotype of negative CR1 was determined by a autosomal recessive gene. Among 112 SLE patients, 73 (65%) showed persistently negative CR1 during remission for over 26 months of follow-up, although the CR1 levels did vary with the disease activity in 22 SLE patients. These results show that the relative risk for developing SLE in persons with negative CR1 is 19. CR1 activity appears to be an important genetic factor related the development of SLE.

C3BI formation at the time of complement enhancement in malnourished rats

We have investigated the ability of lentinan to increase host resistance to certain bacterial infection in malnourished states by enhancement of complement (C3) activity. It is considered that generation of C3b or C3bi is closely related to the activation of macrophages due to binding to complement receptor 3 (CR3) which is present on the surface of phagocytic and cytotoxic cells. We developed a novel method using an Immune Adherence Hemagglutination (IAHA) pattern to assess the formation of C3b and C3bi in vitro. The effect of complement activators was also evaluated. The C3b formation capacity of the sera was measured as IAHA pattern by the addition of dithiothreitol (DTT) which prevents C3bi formation by factors I and H and/or CR1. Formation of C3bi was considered as the range of difference between the end titers of IAHA with or without DTT. The administration of 2mg/kg and 6mg/kg of Znchlorophyllin and 2mg/kg of lentinan could enhance C3 levels and C3b and C3bi formation activities in malnourished rats. C3bi formation was closely related to the phagocytic activities of peritoneal macrophages. We also confirmed that the CR3 site on the surface of monocytes blocked by OKM1 monoclonal anti-CR3 antibody reduced phagocytosis of GEAC3bi particles. These results suggest that phagocytic activity or the clearance capacity of macrophages is enhanced through the interaction of macrophages and increased C3bi formation.

Monoclonal antibodies to mouse complement receptor type 1 (CR1). Their use in a distribution study showing that mouse erythrocytes and platelets are CR1-negative.

mAb to murine C receptor type 1 (CR1) were produced and three of them were characterized. One antibody, designated as 8C12, immunoprecipitated a protein of 190,000 Mr from a detergent extract of surface-labeled spleen cells and stained spleen B but not T lymphocytes in fluorescent flow cytometry. It inhibited both CR1-mediated rosette formation and the cofactor activity of CR1 for factor I-mediated cleavage of C3b, suggesting that it recognizes the ligand-binding site of CR1. The two other antibodies, designated as 7G6 and 7E9, recognized different epitopes from that recognized by 8C12, and they cross-reacted with a protein of 150,000 Mr that is present in a spleen extract. The distribution of CR1 in murine hemopoietic cells was studied by binding experiments with radiolabeled 8C12 and fluorescent flow cytometry. When CR1 was not detected by 8C12 alone, the two other antibodies were used in combination with 8C12 to confirm the negative results. Almost all B lymphocytes from the spleen, lymph nodes, and peripheral blood were CR1 positive. Most of the Thy-1-positive lymphocytes from these tissues were CR1 negative. Thymus lymphocytes were also CR1 negative. Peritoneal macrophages and chemotactic factor stimulated but not unstimulated peripheral blood granulocytes were CR1 positive. In contrast to human E, mouse E were CR1 negative. This pattern of distribution was consistent with previous results obtained by rosette assays. Although mouse platelets cause immune adherence hemagglutination with C3b-bearing SRBC, they are CR1 negative. Three other lines of evidence also indicated that platelets are CR1 negative. First, no band of CR1 was demonstrated by immunoprecipitation with 8C12 of an extract of surface-labeled platelets. Second, 8C12, which inhibited rosette formation by lymphocytes, alone or in combination with 7G6 and 7E9, did not inhibit immune adherence between platelets and C3b-bearing SRBC. Third, polyclonal rabbit IgG prepared from anti-mouse CR1 antiserum did not inhibit immune adherence by platelets. These results strongly suggest that the C3b-binding factor(s) on mouse platelets is different from CR1 and that processing of C3b-bearing immune complexes in mouse blood may be mediated by a new and as yet unidentified C3b-binding factor(s).

Specificity of skin test with varicella-zoster virus antigen in varicella-zoster and herpes simplex virus infections

Specificity of the skin test with varicella-zoster virus (VZV) antigen was examined in guinea pigs infected with herpes simplex virus (HSV) type 1 or VZV and in children with a history of HSV infection who developed varicella. Infected guinea pigs responded positively only to homologous virus. No cross-reaction between HSV and VZV was detected in the skin test, as well as in the neutralization test in infected guinea pigs, suggesting that the VZV skin test is specific for immunity to VZV infection. Twelve children were infected with HSV during an HSV epidemic and subsequently developed varicella in institutional settings. During the 2.5-month period between the HSV and VZV infections, the immune status of the children to VZV was negative both in the skin test and in the antibody test, although antibody to HSV was detected by an immune adherence hemagglutination test. After VZV infection, all responded positively both in the skin test and in the antibody test (immune adherence hemagglutination test) to VZV. These results suggest that the VZV skin test is specific for immunity to VZV infection, not cross-reactive to HSV infection in humans. This specificity will be of value in screening susceptibility or immunity to VZV, irrespective of prior HSV infection.

Four serotypes of haemorrhagic fever with renal syndrome viruses identified by polyclonal and monoclonal antibodies.

Antigenic relationships among 20 strains of haemorrhagic fever with renal syndrome (HFRS) viruses isolated in Korea, China, U.S.S.R., Finland, Japan and U.S.A. were examined with rat immune sera, patient sera, eight monoclonal antibodies against the SR-11 strain and 10 monoclonal antibodies against the 76-118 strain. Antigen analyses by indirect immunofluorescent antibody and immune adherence haemagglutination tests using polyclonal and monoclonal antibodies demonstrated that HRFS viruses may be divided into four serotypes, i.e. Apodemus (Type 1), Rattus (Type 2), Clethrionomys (Type 3) and Microtus (Type 4). Further, it was demonstrated that Type 1 could be divided into three subtypes and Type 3 into two subtypes. The two sets of monoclonal antibodies were useful for identification of the antigenic types of viruses isolated from patients in endemic areas.

Comparative prevalence of rabies antibodies among household and unclaimed/stray dogs as determined by the immune adherence haemagglutination assay.

The immune adherence haemagglutination assay (IAHA), widely used for human viral disease diagnosis, has been adapted for detection of rabies virus antibodies in dog sera. Rabies virus antibody titres obtained by the IAHA correlated well with those obtained by the currently accepted test for rabies antibody determination, the rapid-fluorescent-focus-inhibition test (RFFIT). Although it is not known if the antibodies detected in IAHA test represent neutralizing antibodies against rabies, IAHA has several advantages over the RFFIT: the IAHA is rapid, requiring about seven hours for results to be available; it is relatively inexpensive and easy to perform; uses reagents commonly available in any routine virology laboratory; and uses inactivated rabies virus, thus eliminating hazards associated with the use of live virus in RFFIT. Using this test we found that rabies antibody titres were significantly higher, and at the same time more prevalent, among household dogs than among the unclaimed/stray dogs. The results re-emphasize the increased hazard associated with unclaimed/stray dogs and the need for vaccination of all dogs.

Application of immune adherence hemagglutination test in the screening of blood donors carrying a high titer antibody to varicella-zoster virus.

The immune adherence hemagglutination (IAHA) test was compared with the complement fixation (CF) test and fluorescent antibody (FA) test to measure the antibody titer to varicella-zoster virus (VZV) in 70 sera of convalescents 2 to 8 weeks after herpes zoster onset. The IAHA titer correlated with the FA titer, but not with the CF titer which was lower than the IAHA and FA titers. Then, the IAHA test was used for screening of blood donors with a high titer (higher than 64 units) of antibody to VZV from 2,592 blood donors. About 14% of the sera from the donors aged 16 to 19 years had an antibody titer higher than 64 units, about 10% of sera from the donors aged 20 to 49 years, and 5.6% of sera from the donors older than 50 years. An average positive rate was about 9%, indicating that an enough VZV immune plasma with a high titer of antibody might be obtained from blood donors.