99 cell antibodies may appear after immunisation with virus in tissue-culture. Such antibodies would be difficult to distinguish from antiviral antibodies. Until a varicella-zoster vaccine has been used in proven susceptibles and a persistent specific immune response can be documented, it is difficult to assess the effect of vaccination against varicella. Meanwhile zoster immune globulin can be used to protect high-risk susceptibles who are inadvertently exposed to varicella; this preparation is effective and non-toxic.3
COUNTER ELECTROPHORESIS AND DETECTION OF VIRUSES
propagated
Department of Pediatrics, New York University Medical Center, 550 First Avenue, New York, N.Y. 10016, U.S.A.
ANNE A. GERSHON.
HUMAN PLACENTAL LACTOGEN AND FETAL ABNORMALITY
SIR,-Your editorial on microbial antigen detection (July 20, p. 138) and the letters by Balfour and Edelman (Nov. 23, p. 1267) and by Churdboonchart and others (Oct. 5, p. 841) indicated the general usefulness of counter electrophoresis (c.E.P.). For several years we have been engaged in field studies of the California encephalitis virus (c.E.v.) group of arboviruses, using standard arbovirus techniques. 1,2 As an adjunct to the complement-fixation (c.F.) test we have used C.E.P. to identify c.E.v. isolates and to screen sentinel animal sera for C.E.v. antibody.3 We are in general agreement with Balfour and Edelman that rabbit antiserum to C.E.V. is more homotypic than hyperimmune mouse ascitic fluid. Our experience is that hamster antiserum to c.E.v. is more BLIND STUDY FOR DETECTION OF C.E.V.
(KEYSTONE AR 5241)
BY
S.C.E.P.
Gau and Dr Cadle
SIR,-Dr (Sept. 28, p. 775) suggest that low serum-human-placental-lactogen (H.P.L.) levels may be associated with fetal congenital anomalies. This is in contrast to the data from Singer et al. and Spellacy et a!.5 By expanding the series, it has been possible to measure serum-H.p.L. levels in 113 serum samples from
homotypic than rabbit antiserum and is therefore superior for subtyping c.E.v. isolates by the C.E.P. technique. For screening sentinel animal sera for antibody to C.E.V. we recommend use of local c.E.v. isolates plus the c.E.v. prototype BFS-283 which has wide cross-reactivity with antisera to other C.E.v. subtypes. We have modified the C.E.P. technique by conducting a second electrophoresis using antiglobulin specific for the globulin of the species used as a source of the c.E.v. antibody. This antiglobulin is placed in the antibody (anodal) well and a second electrophoresis conducted. This technique increases the sensitivity of the test, since weak precipitin reactions that do not produce a visible line of precipitate may now be displayed by sandwiching " the antiglobulin to the invisible antigen-antibody complex. Using this " sandwich " counter electrophoresis (S.C.E.P.) we have been able to detect circulating c.E.v. (Keystone AR 5241) in virsemic rabbits and hamsters, in positive wild mosquito pools, and in single mosquitoes infected in the laboratory. In our evaluation of this technique we conducted a blind study, giving the technologist who conducted "
H.P.L. levels in 113 serum samples taken during normal gestations of fetuses with congenital anomalies.
with
normal pregnancy but where the fetus had a congenital anomaly (see accompanying figure). The results did not differ from the values obtained when the fetus was normal.H.P.L. is correlated with fetal weight and, therefore, small infants resulting from congenital anomalies may have proportionately low H.P.L. values.s It seems from this expanded series that H.P.L. is not useful for diagnosing fetal congenital anomalies and that the maternal serum values are generally not lowered by the fetal abnormality.
women
a
Department of Obstetrics and Gynecology, University of Florida College of Medicine, Gainesville, Florida 32610, U.S.A. 3.
W. N. SPELLACY.
Gershon, A., Steinberg, S., Brunell, P. A. New Engl. J. Med., 1974, 290, 243. 4. Singer, W., Desjardins, P., Friesen, H. G. Obstet. Gynec. 1970, 36, 222. 5. Spellacy, W. N., Buhi, W. C., Schram, J. D., Birk, S. A., McCreary, S. A. ibid. 1971, 37, 567. 6. Spellacy, W. N. Clin. Perinatol. 1974, 1, 65.
S.C.E.P. coded specimens some of which contained virus determined by suckling-mouse isolation and other specimens that were negative by suckling-mouse isolation
the as
(see accompanying table). Of the 62 coded test specimens 33 were positive for c.E.v. AR 5241) by suckling-mouse isolation and 28 of these 33 were identified as positive by S.C.E.P. Of the 29 coded specimens negative for c.E.v. (Keystone AR 5241) by suckling-mouse isolation 28 were identified as negative by S.C.E.P. This indicates a sensitivity of 81-8°o and a specificity of 96-5°o for S.c.E.P. compared to suckling-mouse isolation. We have also demonstrated that group-A arboviruses (Western, Eastern, and Venezuelan equine encephalitis), group-B arboviruses (St. Louis encephalitis), and the rhabdoviruses (Hart Park and Flanders) give c.E.P. reactions in homologous antigen-antibody systems.
(Keystone
Kokemot, R. H., Hayes, J., Boyd, K. R., Sullivan, P. S. J. med. Entomol. 1974, 11, 419. 2. McLerran, J., Arlinghouse, R. Virology, 1973, 53, 247. 3. Gocke, D., Howe, J. Immunology, 1970, 104, 1031. 1.
COUNTER ELECTROPHORESIS AND DETECTION OF VIRUSES
propagated
Department of Pediatrics, New York University Medical Center, 550 First Avenue, New York, N.Y. 10016, U.S.A.
ANNE A. GERSHON.
HUMAN PLACENTAL LACTOGEN AND FETAL ABNORMALITY
SIR,-Your editorial on microbial antigen detection (July 20, p. 138) and the letters by Balfour and Edelman (Nov. 23, p. 1267) and by Churdboonchart and others (Oct. 5, p. 841) indicated the general usefulness of counter electrophoresis (c.E.P.). For several years we have been engaged in field studies of the California encephalitis virus (c.E.v.) group of arboviruses, using standard arbovirus techniques. 1,2 As an adjunct to the complement-fixation (c.F.) test we have used C.E.P. to identify c.E.v. isolates and to screen sentinel animal sera for C.E.v. antibody.3 We are in general agreement with Balfour and Edelman that rabbit antiserum to C.E.V. is more homotypic than hyperimmune mouse ascitic fluid. Our experience is that hamster antiserum to c.E.v. is more BLIND STUDY FOR DETECTION OF C.E.V.
(KEYSTONE AR 5241)
BY
S.C.E.P.
Gau and Dr Cadle
SIR,-Dr (Sept. 28, p. 775) suggest that low serum-human-placental-lactogen (H.P.L.) levels may be associated with fetal congenital anomalies. This is in contrast to the data from Singer et al. and Spellacy et a!.5 By expanding the series, it has been possible to measure serum-H.p.L. levels in 113 serum samples from
homotypic than rabbit antiserum and is therefore superior for subtyping c.E.v. isolates by the C.E.P. technique. For screening sentinel animal sera for antibody to C.E.V. we recommend use of local c.E.v. isolates plus the c.E.v. prototype BFS-283 which has wide cross-reactivity with antisera to other C.E.v. subtypes. We have modified the C.E.P. technique by conducting a second electrophoresis using antiglobulin specific for the globulin of the species used as a source of the c.E.v. antibody. This antiglobulin is placed in the antibody (anodal) well and a second electrophoresis conducted. This technique increases the sensitivity of the test, since weak precipitin reactions that do not produce a visible line of precipitate may now be displayed by sandwiching " the antiglobulin to the invisible antigen-antibody complex. Using this " sandwich " counter electrophoresis (S.C.E.P.) we have been able to detect circulating c.E.v. (Keystone AR 5241) in virsemic rabbits and hamsters, in positive wild mosquito pools, and in single mosquitoes infected in the laboratory. In our evaluation of this technique we conducted a blind study, giving the technologist who conducted "
H.P.L. levels in 113 serum samples taken during normal gestations of fetuses with congenital anomalies.
with
normal pregnancy but where the fetus had a congenital anomaly (see accompanying figure). The results did not differ from the values obtained when the fetus was normal.H.P.L. is correlated with fetal weight and, therefore, small infants resulting from congenital anomalies may have proportionately low H.P.L. values.s It seems from this expanded series that H.P.L. is not useful for diagnosing fetal congenital anomalies and that the maternal serum values are generally not lowered by the fetal abnormality.
women
a
Department of Obstetrics and Gynecology, University of Florida College of Medicine, Gainesville, Florida 32610, U.S.A. 3.
W. N. SPELLACY.
Gershon, A., Steinberg, S., Brunell, P. A. New Engl. J. Med., 1974, 290, 243. 4. Singer, W., Desjardins, P., Friesen, H. G. Obstet. Gynec. 1970, 36, 222. 5. Spellacy, W. N., Buhi, W. C., Schram, J. D., Birk, S. A., McCreary, S. A. ibid. 1971, 37, 567. 6. Spellacy, W. N. Clin. Perinatol. 1974, 1, 65.
S.C.E.P. coded specimens some of which contained virus determined by suckling-mouse isolation and other specimens that were negative by suckling-mouse isolation
the as
(see accompanying table). Of the 62 coded test specimens 33 were positive for c.E.v. AR 5241) by suckling-mouse isolation and 28 of these 33 were identified as positive by S.C.E.P. Of the 29 coded specimens negative for c.E.v. (Keystone AR 5241) by suckling-mouse isolation 28 were identified as negative by S.C.E.P. This indicates a sensitivity of 81-8°o and a specificity of 96-5°o for S.c.E.P. compared to suckling-mouse isolation. We have also demonstrated that group-A arboviruses (Western, Eastern, and Venezuelan equine encephalitis), group-B arboviruses (St. Louis encephalitis), and the rhabdoviruses (Hart Park and Flanders) give c.E.P. reactions in homologous antigen-antibody systems.
(Keystone
Kokemot, R. H., Hayes, J., Boyd, K. R., Sullivan, P. S. J. med. Entomol. 1974, 11, 419. 2. McLerran, J., Arlinghouse, R. Virology, 1973, 53, 247. 3. Gocke, D., Howe, J. Immunology, 1970, 104, 1031. 1.
