Persistence of immunity to varicella in children with leukemia immunized with live attenuated varicella vaccine

To determine the safety and efficacy of varicella vaccine, we studied 437 children in remission from leukemia who were immunized with live attenuated varicella virus. Three hundred one of the patients received two doses of vaccine and 136 received a single dose of vaccine from 1 of 10 lots from two manufacturers. The patients have been followed for an average of three years (range, one to six). Seroconversion occurred in 88 percent of the 437 children after the first dose of vaccine and in 98 percent after one or two doses. The proportions of patients who were seronegative after one, three, and five years were 20, 25, and 30 percent, respectively, with little change over time in the geometric mean titers of specific antibody (6.3, 6.5, and 5.7, respectively). Chickenpox has been documented in 36 vaccinated patients (8 percent) who had 3 to 640 vesicles (mean, 100), mild illness, and no complications. Of the 83 vaccinated patients exposed to varicella within their families, 11 had chickenpox; the attack rate was 14 percent (8 percent among seropositive patients, 29 percent among seronegative patients). There was no relation between the time since vaccination and either the attack rate or the severity of the breakthrough illness. Two doses of vaccine appeared to be no more effective than a single dose. Of the 372 patients receiving maintenance chemotherapy when immunized, 149 (40 percent) had a rash, which was treated with acyclovir in 16 children (4 percent) and became a severe febrile illness in 4. These reactions were not fatal and were all associated with vaccine lots, the use of which has since been discontinued. We conclude that in children in remission from leukemia, varicella vaccine is safe and induces an immunity to chickenpox that persists for more than three years.

Immunization of healthy adults with live attenuated varicella vaccine

Live attenuated varicella vaccine was administered to healthy varicella-susceptible adults. Of 187 adults immunized with the Oka strain of vaccine, seroconversion to varicella-zoster virus (VZV) occurred in 82% after one dose and in 94% after two doses. Adverse effects were unusual. After immunization, one subject developed mild zoster caused by wild-type virus. Twelve adults developed a mild breakthrough case of chickenpox after exposure to VZV. Protection after household exposure was observed in nine (56%) of 16; however, the illness in all seven patients with breakthrough illness was modified, with an average of only 24 vesicles. Subjects seropositive at household exposure were unlikely to develop a breakthrough illness. Approximately 25% of vaccinees who seroconverted lost detectable antibodies to VZV after vaccination, but even those who became seronegative were partially protected. Varicella vaccine offered significant protection against severe chickenpox in healthy adults.

Western blot analysis of antibody to varicella-zoster virus

We used western blot (WB) to compare the IgG response to varicella-zoster virus (VZV) after chickenpox (CP), zoster, and administration of a live attenuated varicella vaccine (LAVV). After CP, 13 of 14 normal children had antibody to glycoprotein (gp) I (99 and 92 kilodaltons [kDa]), 11 had antibody to gpII (133 kDa), and 10 had antibody to gpIII (119 kDa). Bands at 150 and 35 kDa were also seen in 13 and 11 sera, respectively. Bands to gpI, gpII, and p35 were more intense after zoster than CP. After one dose of LAVV, eight of eight normal children had gpI antibody. In leukemic children, gpI antibody appeared in 18 (56%) after one dose and in 25 (89%) after two doses. Upon household exposure, leukemic vaccinees who developed CP were less likely than those protected to have prior gpIII and p35 antibodies. As seen after zoster, WBs after breakthrough CP showed intense responses to VZV antigens. Thus, WB helps distinguish secondary from primary antibody responses to VZV.

The risk of zoster after varicella vaccination in children with leukemia

We examined the incidence of zoster in 346 children with underlying acute lymphoblastic leukemia who were immunized with live attenuated varicella vaccine while in remission. We also compared a subset of 84 of these children with a matched group of 84 children with leukemia who had had natural infection with varicella. Of the 346 vaccinated children, 5 (1.45 percent) became infected with zoster after 10,878 months of observation, for an incidence of 0.552 case per 100 person-years. Among the matched pairs of subjects, zoster occurred in 3 (3.6 percent) of the 84 vaccinated subjects during 2936 months of observation--an incidence of 1.23 cases per 100 person-years--and in 11 (13.1 percent) of the subjects with natural infection during 4245 months--an incidence of 3.11 cases of zoster per 100 person-years. Although the incidence of zoster was more than twice as high in the control children as in the vaccinated children (3.11 vs. 1.23 cases per 100 person-years), a Kaplan-Meier product-limit analysis revealed no significant differences in incidence between the two groups. Children from both groups in whom leukemia recurred were more likely to contract zoster than those who did not have a recurrence (7 of 35 vs. 7 of 133, P less than 0.025). Zoster was not a marker for impending relapse. No case of zoster was severe or disseminated. We conclude that the incidence of zoster following immunization with live attenuated varicella vaccine is no greater than that following natural varicella infection.

Molecular epidemiology of live, attenuated varicella virus vaccine in children with leukemia and in normal adults

Restriction endonuclease analysis of varicella-zoster virus (VZV) DNA has been used in unraveling the complex epidemiology of VZV infections in individuals immunized with a live, attenuated varicella virus vaccine. Early rashes appearing within the first six weeks after vaccination are invariably due to vaccine virus. True breakthrough infections with wild-type VZV also occur in vaccinees. Five cases of zoster have been seen in leukemic children vaccinated while in remission. One case appeared 22 months after vaccination in the same general area as the inoculation. The virus isolated was vaccine derived. A second case of zoster appeared in a dermatome unrelated to the sites of vaccination approximately 19 months after apparently natural varicella. This virus was wild type. Vaccine virus can therefore establish latency and can later reactivate as herpes zoster.

Live attenuated varicella vaccine

Live attenuated varicella vaccine will in all probability soon be licensed in the United States for immunization of healthy children and adults and certain immunocompromised children. This vaccine can be expected to protect susceptibles from varicella (or to modify it) in those subsequently exposed to the wild virus. The vaccine is safe, immunogenic, and is not associated with an increase in the incidence of zoster.

Live attenuated varicella vaccine use in immunocompromised children and adults

Live attenuated varicella vaccine has been administered to 307 children with leukemia in remission and to 86 healthy adults. The vaccine was well tolerated and immunogenic. The major side effect in leukemic children receiving maintenance chemotherapy was development of a vaccine-associated rash. Vaccinees in whom a rash developed were potentially somewhat infectious to others about 1 month after immunization. Vaccination was not associated with an increase in the incidence of herpes zoster or in relapse of leukemia. Vaccination provided excellent protection against severe varicella. It was associated with a significant decrease in the attack rate of chickenpox following an intimate exposure to varicella-zoster virus, conferring about 80% protection in leukemic children. The cases of breakthrough varicella that occurred were mild. Thus, the vaccine may either prevent or modify varicella in high-risk individuals. It may also have use for prevention of nosocomial varicella.

Determination of immunity to varicella-zoster virus by means of an intradermal skin test

An intradermal varicella skin test, utilizing heat-inactivated noninfectious viral antigen, was evaluated in 16 adults known to be immune or susceptible to varicella and in 109 adults with no history of varicella. The skin test was well tolerated, compared favorably with established methods of determining immunity to varicella, and accurately predicted which subjects would develop clinical varicella after close exposure.

Seroepidemiologic behavior of varicella zoster virus infection in a semiclosed community after introduction of VZV vaccine

A survey of varicella and measles has been made in a semiclosed institution housing infants and children in Osaka since 1950. Live measles and varicella vaccines were introduced into the institution in 1974 and 1975, respectively. Nine of 10 measles outbreaks occurred during the 24 years before use of measles vaccine, and only one occurred during the 9 years after introduction of measles vaccine. In contrast, the incidence of varicella outbreaks has not been reduced after introduction of varicella vaccine, although the rate of immune individuals in the population against varicella has been kept at 74.2% for the 8 years since 1975, which was higher than that against measles (65.8%) during the same period. All successfully vaccinated children, however, were resistant to clinical varicella, and the number of clinical cases has been markedly reduced. Using the fluorescent antibody to membrane antigen and varicella zoster virus skin testing, the kinetics of secretory, humoral, and cellular immune responses to VZV was examined in vaccinated and naturally infected subjects and found to be comparable in both groups during repeated exposure to varicella epidemics. These results suggest that the seroepidemiologic behavior of varicella would not be significantly altered after introduction of varicella vaccine, in contrast to that of measles since general use of measles vaccine.

Live attenuated varicella vaccine in children with leukemia in remission

One-hundred-ninety-one children with acute leukemia in remission for at least one year were immunized with 1 or more doses of live attenuated varicella vaccine. All were susceptible to varicella prior to vaccination. The only significant side effect was mild to moderate rash, seen especially in children with maintenance chemotherapy temporarily suspended for one week before and one week after vaccination. Children with rash were at some risk (10%) to transmit vaccine virus to varicella susceptibles with whom they had close contact.

Mucosal cell-mediated immunity to varicella zoster virus: role in protection against disease

By indirect immunofluorescence, enzyme-linked immunosorbent assay, and in vitro lymphocyte proliferation, we studied the antibody and cell-mediated immune response to varicella zoster virus (VZV) in serum, peripheral blood lymphocytes, and tonsillar lymphocytes in 49 children before and after tonsillectomy and adenoidectomy. Among the naturally infected patients seropositive for VZV antibody, most demonstrated VZV-specific proliferation in the peripheral blood and tonsillar lymphocytes, with activity consistently higher in the tonsillar lymphocytes. Several patients seronegative for VZV antibody and without a prior history of clinical chickenpox also manifested VZV-specific proliferation in the tonsillar lymphocytes, and less frequently in peripheral blood lymphocytes. Of these, six children with high levels of activity in tonsillar lymphocytes, with or without high levels in the peripheral blood lymphocytes, failed to develop disease after intimate exposure to VZV in family settings. On the other hand, three other subjects with little or no VZV-specific proliferative activity in the tonsillar lymphocytes developed disease after similar exposure to VZV. These observations suggest the development of VZV-specific mucosal cellular immunity after overt or inapparent exposure to VZV. The appearance of such immunity appears to have a protective role against reinfection even in the absence of detectable serum antibody.

Live attenuated varicella vaccine. Efficacy for children with leukemia in remission

One hundred ninety-one varicella-susceptible children with leukemia in remission were immunized with live attenuated varicella vaccine. There was serological evidence of an immune response in approximately 80% after one dose and in more than 90% after two doses. The major side effect was mild to moderate rash, seen especially in children with maintenance chemotherapy suspended for one week before and one week after vaccination. Children with rash had higher antibody titers than those without rash, but those with rash were also at risk (10%) to transmit vaccine virus to others. Twenty-two vaccinees subsequently had household exposures to varicella or zoster. The attack rate of clinical varicella in these vaccinees was 18%, significantly lower than the attack rate of approximately 90% in varicella-susceptible persons with household exposures. All cases of clinical illness were extremely mild, with an average of about 50 vesicles. The mild character of the illness was clearly different than varicella in unimmunized children receiving chemotherapy for leukemia. Varicella vaccine was approximately 80% effective in preventing clinical varicella in children with leukemia and completely effective in preventing severe varicella in this high-risk group.

Symposium on infectious complications of neoplastic disease (Part II). Immunoprophylaxis of varicella-zoster infections

Because it is possible to identify groups of persons with a high risk of varicella development and also because it is possible to anticipate when an attack may occur, immunoprophylaxis for varicella has met with great success. In contrast, the nature of zoster--its unpredictability and low attack rate--makes immunoprophylaxis much more difficult to implement. Varicella may be modified by administration of varicella-zoster immune globulin within three days of a known exposure to the virus. Although interferon has not yet been used in an attempt to prevent or modify varicella in humans, it has been used successfully to abort an outbreak of simian varicella in a monkey colony. Thus it might be clinically useful, particularly for those who cannot be given varicella-zoster immune globulin within three days of exposure. Transfer factor has also been shown to induce at least partial immunity to varicella in children with leukemia. The duration of this protection is unknown, and further study of the efficacy of transfer factor against both varicella and possibly even against zoster seems warranted. Live attenuated varicella vaccine, although still experimental, seems now to be the most practical way to prevent severe varicella in high-risk persons. The vaccine is safe and immunogenic, even in children with underlying leukemia who are still receiving chemotherapy. Studies in Japan, Europe, and the United States have shown that most vaccinated leukemic children who are exposed are protected against severe disease, although mild breakthrough cases have been reported. Varicella vaccine's potential to cause zoster remains under study.

Clinical reinfection with varicella-zoster virus

Eight patients became clinically reinfected with varicella-zoster virus despite the presence of specific antibody in the blood three days to six months before the onset of illness. One patient had had varicella previously; a second had been immunized with live, attenuated varicella vaccine 10 months earlier. While it was suspected that these patients experienced a reactivation of latent virus that caused atypical disseminated zoster rather than varicella, detailed study of the vaccinated child suggests that this was not the case; by restriction-endonuclease techniques, this vaccinee was shown to have been infected with wild-type varicella-zoster virus despite the presence of specific antibody and cellular immunity to the virus. All cases clinically resembled chickenpox. Thus, not only subclinical varicella (manifested by a rise in antibody titer after close exposure) but also clinical reinfection with the virus can occur. Clinical reinfection probably develops more frequently in immunocompromised than in immunocompetent individuals. Reinfections are usually mild.

Evaluation of the anticomplement immunofluorescence test for detection of antibody to varicella-zoster virus

The anticomplement immunofluorescence (ACIF) test was compared with complement fixation and fluorescent antibody to membrane antigen procedures for the detection of antibody to varicella-zoster virus. All of 50 sera from pregnant women contained antibody measured by ACIF (titer, greater than or equal to 1:10); only 27 (54%) were positive by complement fixation (P less than 0.01). For 16 paired sera obtained before and after varicella-zoster virus infection and tested by ACIF and fluorescent antibody to membrane antigen, the result agreed in 27 determinations (sensitivity, 94%; specificity, 81%). Of 99 sera submitted for routine determinations of immune status to the virus, 89 showed comparable results for both tests (sensitivity, 92.5%; specificity, 88%). The ACIF test offers a specific and sensitive alternative to the fluorescent antibody to membrane antigen procedure for the detection of antibody to varicella-zoster virus. In addition, the ACIF test is rapid, easy to perform, and uses commercially available reagents.

IgM to varicella-zoster virus: demonstration in patients with and without clinical zoster

Antibody to varicella-zoster (VZ) virus of the IgM type was detected in sera from 50% of persons with clinical zoster, 67% of asymptomatic varicella immunes with a recent intimate exposure to VZ virus and 22 to 40% of varicella immunes with no symptoms of zoster or known exposure to the virus. No VZ IgM was found in newborn sera or in sera from persons susceptible to varicella, demonstrating specificity of the VA IgM assay. Since development of specific IgM is associated with acute infection, these data suggest that reinfection with VA virus occurs and also that antigenic stimulation due to exposure to endogenous VZ virus may occur. We hypothesize that during reactivation of VZ virus, persons with intact VZ cell-mediated immunity (CMI) remain asymptomatic but that those with depressed VZ CMI may develop clinical zoster. These data suggest that there is an unstable relationship between VZ virus and the human host.

Inactivation of varicella zoster virus in vitro: effect of leukocytes and specific antibody

Inactivation of varicella zoster virus in vitro by nonadherent, mononuclear peripheral blood leukocytes and antibody is described. When leukocytes and specific antibody were incubated with this virus, marked inactivation of the virus occurred. In contrast, leukocytes alone or with serum devoid of varicella zoster antibody caused only a small degree of inactivation of varicella zoster virus. The leukocytes involved appeared not to be monocyte-macrophages or T or B lymphocytes, and only minute amounts of specific antibody were required. We had found previously that leukocytes from unsensitized (varicella susceptible) as well as sensitized (varicella immune) donors could cause this reaction. We therefore propose that the reaction may be a form of antibody-dependent cellular cytotoxicity, as has been described for 51Cr release by lymphoid (K) cells for other herpesviruses.

Antibody responses to varicella-zoster virus and the role of antibody in host defense

Antibody titers to varicella-zoster (VZ) virus in persons aged 1-85 years were measured. Through age 50, the percent of seropostitive individuals continued to rise. There was no fall in geometric mean titer with aging, and there may have been an increase in VZ antibody titer in older persons. Thus, a fall in VZ antibody with increasing age does not seem likely to account for the increased incidence of zoster in the elderly. Similarly, immunocompromised patients who are more likely to develop zoster than normals did not have lower VZ antibody titers than normal persons. Finally, immunocompromised persons with disseminated zoster had antibody titers that were somewhat higher that those of immunocompromised persons with localized zoster. It appears that humoral immunity has little or no influence on either the development or the course of herpes zoster.

Fatal reaction to dapsone during treatment of leprosy

A Burmese boy being treated with dapsone (diaminodiphenylsulfone [DDS]), 100 mg daily, for lepromatous leprosy had a fatal reaction to the drug 3 weeks after therapy was started. The clinical symptoms and progression of illness conform well to a "DDS syndrome" first described in the early 1950s. Although the syndrome clinically resembles infectious mononucleosis, neither Epstein-Barr virus nor cytomegalovirus was implicated as an etiologic agent in this case. The syndrome has been recognized during initiation of dapsone therapy for lepromatous leprosy and has led to the use of a prolonged induction period with initial dosages as low as 25 mg/week. However, because dapsone resistance has been recognized in some strains of Mycobacterium leprae, slow induction of therapy has been replaced with the schedule used for this patient. This report of a fatal reaction to dapsone emphasizes the need for caution when initiating therapy with the drug at full dosage.

Rapid diagnosis of varicella-zoster virus infections by countercurrent immunoelectrophoresis

A simple, accurate, and rapid method for laboratory diagnosis of varicella-zoster virus (VZV) infections using countercurrent immunoelectrophoresis (CIE) is described. CIE uses zoster convalescent-phase serum to detect VZV antigen in vesticular fluid. Eighty-six patients were studied, 58 with VZV infections and 28 with vesicular or bullous rashes due to causes other than VZV infection. All patients with documented VZV infection had positive CIE tests for VZV, and the controls were uniformly negative. VZV antigen could be detected up to 15 (varicella) or 16 (zoster) days after the onset of rash. The sensitivity of CIE for detection of VZV antigen was compared with results of viral isolation, immune adherence hemmagglutination, and an indirect enzyme-linked immunosorbent assay.

Adenosine deaminase deficiency without immunodeficiency: clinical and metabolic studies

A child diagnosed at birth as deficient in red blood cell adenosine deaminase (ADA) but with substantial residual lymphocyte ADA has been evaluated for two and one-half years. The only immunologic abnormality observed was hypogammaglobulinemia during the fifth month of life. This was unexpected because children with total ADA deficiency either have severe combined immunodeficiency or selectively greater impairment of cellular than humoral immunity. The absence of severe combined immunodeficiency in this child was associated with normal lymphocyte content of ATP, dATP, and cyclic 3'5'-adenosine monophosphate, potentially toxic metabolites which are elevated in ADA-deficient immunodeficient children.

Live attenuated Varicella-Zoster vaccine

Varicella-zoster (VZ) virus causes two diseases, varicella and zoster. Because it was recognized that, after varicella, latent VZ virus persisted in the host and because varicella was thought to be a milde disease, there was little impetus in North America to develop a live VZ vaccine. More recently, it has become apparent that currently available methods of prevention and treatment of severe varicella are not always efficacious. With the development of a live attenuated VZ vaccine by Takahashi and the successful use of the vaccine in immunocompromised children in Japan, there has been an increased interest in North America in immunization against varicella. In this article the natural history of VZ infections and the immunologic reactions to VZ virus are described, and the development and use of VZ vaccine in Japan are reviewed. Plans for trials of VZ vaccine in immunocompromised North American children are outlined. The major questions concerning the large-scale use of VZ vaccine are presented.

Live attenuated rubella virus vaccine: comparison of responses to HPV-77-DE5 and RA 27/3 strains

The responses of seronegative adults to two live attenuated rubella virus vaccines were compared. Of 50 women who received the HPV-77-DE5 strain, 49 (98%) had an antibody response; the geometric mean antibody titer (GMT) was 1:38 at two to five months and 1:59 at six to 14 months. Of 66 women and three men who received the RA 27/3 strain all (100%) had an antibody response; the GMT was 1:55 at two to five months and 1:75 at six to 14 months. The incidence of mild to moderate transient clinical reactions, occurring in approximately one-fourth of those vaccinated, was similar for both groups. The serologic response to both vaccines was excellent.

Cell-mediated immunity to varicella-zoster virus measured by virus inactivation: mechanism and blocking of the reaction by specific antibody

The process whereby varicella-zoster (V-Z) virus is inactivated in vitro by immune human peripheral blood leukocytes stimulated with V-Z antigen was examined. It was found that stimulation of leukocytes by V-Z antigen, but not by other viral antigens, was required for inactivation of V-Z virus to occur. Viral inactivation could be blocked by addition of V-Z antiserum to either the stimulation phase of the reaction or the inactivation phase, further demonstrating the specificity of the reaction. In addition these blocking experiments suggested that modulation of V-Z membrane antigen by antiserum occurred with an accompanying loss of immunological recognition of virus-infected cells. Inactivation of V-Z virus in vitro in this study appeared not to be dependent upon the secretion of interferon or upon antibody-dependent cellular cytotoxicity. The specific cells required for V-Z inactivation were T lymphocytes and monocytes (macrophage precursors).

Cellular and humoral immune responses to varicella-zoster virus in immunocompromised patients during and after varicella-zoster infections

Humoral and cell-mediated immune responses to varicella-zoster (V-Z) virus were assessed in patients during and after V-Z infections. Ongoing V-Z infections was associated with minimal cellular immunity but not necessarily with poor humoral immunity. Recovery from V-Z infection was associated with a vigorous cellular immune response. Cell-mediated immunity to V-Z virus was demonstrable for years after varicella, but responses were lower in immunocompromised patients than in normal individuals.

Antibody to varicella-zoster virus after passive immunization against chickenpox

Antibody titers to varicella-zoster virus were measured in varicella-susceptible immunocompromised children 48 h after they received either one of two lots of zoster immune globulin (ZIG) or a selected lot of immune serum globulin (ISG). Globulin was given to modify varicella in these children after exposure to varicella or zoster. Indirect immunofluorescence antibody titers (FAMA) of children after receipt of globulin ranged from less than 1:2 to 1:32. Geometric mean FAMA titers were highest after 1.2 ml of ISG per kg (FAMA titer 1:128) and 0.16 ml of ZIG lot A per kg (FAMA titer 1:1,024). Selected batches of ISG titering 1:128 or greater by FAMA, at a dose of 1.2 ml/kg, may be used to attempt to modify varicella in susceptible high-risk individuals when ZIG is not available.

Varicella-zoster virus. Prospects for active immunization

A live attenuated varicella-zoster (V-Z) virus vaccine has been developed and tested by Dr. M. Takahashi and his colleagues in Japan. This vaccine appears to prevent varicella and is associated with minimal side effects even in patients at high risk to develop severe varicella. Antibody to V-Z virus appears after V-Z vaccination. This antibody has been detected by a variety of serologic technics, and it has been demonstrated to persist for as long as two years after vaccination. Thus far, V-Z vaccine has not been associated with subsequent zoster, but long-term studies will be required before this possibility can be ruled out.

Immune adherence hemagglutination: further observations on demonstration of antibody to varicella-zoster virus

The immune adherence hemagglutination test for measurement of antibody to varicella-zoster (V-Z) virus is well suited to performance in a routine serology laboratory. This test is useful in assessing susceptibility to varicella, measuring antibody to V-Z virus in globulin preparations, and evaluating some effects of passive immunization. Since the complement-fixation test for antibody to V-Z virus lacks sensitivity and the fluorescent antibody to membrane antigen test is not readily available, the immune adherence hemagglutination test may be of practical value in patient management.

Antibody to Varicella-Zoster virus in parturient women and their offspring during the first year of life

A nursery outbreak of varicella is reported. Serum from 200 parturient women and 131 of their offspring were studied for antibody to varicella-zoster (V-Z) virus to analyze their immunity to varicella. Antibody titers were measured by the sensitive fluorescent antibody to membrane antigen (FAMA) technique. It was found that approximately 5% to 16% of women of child-bearing age in New York City are susceptible to varicella. Women from Puerto Rico or other subtropical and tropical areas are more likely to be susceptible (16%) than others (5%). Infants born to mothers with detectable V-Z FAMA titers almost always had detectable V-Z antibody at birth. In serial serum specimens obtained from 67 initially seropositive babies during the first year of life, it was found that by 6 months of age most infants were no longer passively protected against varicella. These observations may explain why varicella is not uncommonly observed in young babies.

Cell-mediated immunity to varicella-zoster virus demonstrated by viral inactivation with human leukocytes

Cell-mediated immunity to varicella-zoster (V-Z) virus in persons immune to varicella has been demonstrated, using a tissue culture technique. Cell-mediated immunity was reflected by the ability of peripheral leukocytes (lymphocytes and monocytes) from human donors to inactivate V-Z virus. Leukocytes were stimulated by the addition of noninfectious V-Z antigen to cultures newly infected with V-Z virus. Several days leter, the V-Z virus in these cultures was titered. When leukocytes from donors immune to caricella were used, a significant decrease in V-Z titer, compared with controls, was noted. When leukocytes from donors susceptible to varicella were tested, no decrease in V-Z virus titer was found. A mixed population of lymphocytes and monocytes from immune donors was required to demonstrate inactivation of V-Z virus. The development of specific cell-mediated immunity to V-Z virus may play a role in termination of varicella and in prevention of second attacks of this disease.

Detection of antibody to Varicella-Zoster virus by immune adherence hemagglutination

A serologic test for measurement of antibody to V-Z virus by immune adherence hemagglutination is described. Initial evaluation of the test has shown it to be highly sensitive, specific, rapid, and simple to perform. The V-Z antigen may be stored at -70 degrees, and the test could be performed in any routine serology laboratory.