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TICK-BORNE ENCEPHALITIS VIRUSES
1026
Then indeed the " dissensions and bankruptcy " of which you warn us might well become a reality. Our seniors often tell us that there is no advantage to them from either course, and that they are only concerned to provide for the younger pathologists in whose hands the future lies. At the same time they tend, perhaps, to ignore the experience of most of those who discuss such matters with these younger pathologists, and find that they are mostly in favour of a College. The young men do not seem to be afraid of starting in a small way provided that they can feel genuinely independent and not a sort of appendage to another college. Their " image " of pathology is of a subject which is of real importance in its own right and which can therefore expect its own separate and
faculty ?
individual organisation. If we are to build surely for the future, independence is the only safe choice. When I have reached retiring age, I do not want my juniors to be able to say to me: " You and your colleagues made a fine mess of things in 1960. Here we are stuck in the College of Physicians where we are not really happy, but it will be very difficult to break away now. If you had only made the effort to form a College it would be well established by now. Did you have to choose the easy way? Couldn’t you see just a little way in front of your noses ?".
Yours, G. G.
Symposium TICK-BORNE ENCEPHALITIS VIRUSES FROM A CORRESPONDENT
THE Institute of Virology of the Czechoslovak Academy of Sciences acted as hosts to virologists from eleven different countries during a four-day symposium last month on the biology of viruses of the tick-borne encephalitis complex. The meetings were held in delightful surroundings at the House of Scientists at Smolenice, near Bratislava. Representatives from almost all the major groups working on this subject were present, and the symposium provided an unusual opportunity for workers from many different disciplines to pool information and exchange ideas in a common approach. In Britain, human infections with louping-ill virus do not present a serious public-health problem; but in Central Europe, Scandinavia, U.S.S.R., and India viruses of the tick-borne encephalitis group are The recent recognition of human a serious menace. infections with viruses of this group in Canada 1and the U.S.A.3 extends the area in which these viruses are known.
J. CASALS (New York) showed how the tick-borne viruses placed with yellow fever and some twenty other arthropodborne viruses into the serological group B on the basis of antigenic relationships. In the past, the tick-borne encephalitis viruses have been considered a homogeneous group in spite of wide differences in the disease patterns they produced in different parts of the world. Dr. D. H. CLARKE (New York) showed that they could be divided into six antigenic subgroups on the basis of haemagglutination inhibition tests with absorbed sera and by agar-gel precipitin tests. The six subgroups were represented by the classical far-eastern Russian spring-summer encephalitis (R.S.S.E.), louping ill, Omsk Dr.
were
1. McClean, D. M., Donaghue, W. L. Canad. med. Ass. J. 1959, 80, 708. 2. Casals, J. ibid. 1960, 82, 355. 3. Thomas, L. A., Kennedy, R.C., Eklund, C. M. Proc. Soc. exp. Biol., N.Y. 1960, 104, 355.
haemorrhagic fever, Kyasanur Forest disease,4 Malayan tickborne Langat virus, and Central European tick-borne encephalitis which included Czechoslovakian, Austrian, Finnish, Polish, Swedish, and Yugoslavian strains, as well as strains The recently described North from European U.S.S.R. American Powassan virus had not yet been examined by these
techniques. These antigenic differences were important because they explained the reported failure of R.S.S.E. vaccine to protect humans (Dr. P. N. BHATT, Poona) or mice (Dr. L. DANES, Prague) against infection with the virus of Kyasanur Forest disease. As in other branches of virology, tissue-culture techniques were gradually replacing older methods for the titration of viruses and for the detection of neutralising antibodies. The use of a plaque technique for the titration of tick-borne encephalitis viruses was described by Dr. J. S. PORTERFIELD (London) and was applied by Dr. V. MAYER, Dr. J. ZAVADA, and Dr. R. SKODA (Bratislava) to Central European strains. Dr. BHATT reported that chick fibroblast cultures were as satisfactory as mice for the primary isolation of Kyasanur Forest disease virus. Czechoslovak workers preferred a twostage process-primary isolation in tissue-culture cells which were later shown to be infected by virtue of their resistance to a challenge virus. Neutralising antibodies were detected by a metabolic inhibition test carried out in Hela cells (Dr. H. LiBIKovA and Dr. J. ViLCEK, Bratislava), by plaque inhibition (Dr. J. S. PORTERFIELD, London), or by the direct inhibition of cytopathic effect in Hela cells (Dr. E. MOLNAR, Budapest) or in pig kidney cells (Dr. D. MALKOvA, Dr. Z. MARHOUL, Dr. V. FRANKOvA, and Dr. V. CERNY, Prague). Vaccines derived from formalinised mouse brain had been used for many years in the U.S.S.R. (Prof. E. N. LEVKOVICH, Moscow, Prof. A. A. SMORODINSTEV, and Dr. V. I. ILYENKO, Leningrad) and formalin-inactivated louping-ill vaccine had been used to protect laboratory personnel (Dr. D. G. FF. EDWARD, Beckenham) and domestic animals (Dr. D. BLASCOVIC
and others, Bratislava). Attempts at producing a vaccine from virus grown in tissue culture were reported from Prague (Dr. R. BENDA and Dr. DANES), from Budapest (Dr. E. MOLNAR), and from the U.S.S.R. The major difficulty was to guarantee complete destruction of infectivity without at the same time reducing the antigenicity of the vaccine. There were many parallels with the poliomyelitis vaccine problems. A further important factor reported by Dr. G. D. ZASUKHINA (Moscow) was that virus grown in tissue culture with a deficient medium was less antigenic than virus grown in a rich medium. The maintenance of the tick-borne viruses in Nature is still not completely understood. The course of infection in an the laboratory mouse, was studied by experimental animal, Dr. P. ALBRECHT (Bratislava) in an elegant series of experiments based on the use of fluorescent antibody techniques. Other animals which may be infected in Nature include bats and, lizards (Dr. J. REHACTK, Dr. J. NosEK, and Dr. M. GRESIKovA, Bratislava), domestic ducks (Dr. E. ERNEK, Bratislava), and coots (Prof. H. A. E. VAN TONGEREN, Leiden). Much remains to be learned about the natural history of this group of viruses. Although the great majority of infections are transmitted by the bites of infected ticks, mechanical transmission by mosquitoes (Dr. Z. ZOTOWSKI and Dr. Z. WROBLEWSKA-MULARCZYKOWA, Warsaw) or fleas (Dr. K. HEYBERGER, Dr. A. SMETANA, and Dr. B. RosiCKY, Prague) may play some small part in the local spread of infection, and infection by the ingestion of milk from infected goats, sheep, and cattle is now well established. The many factors which influence the natural history of viruses of the tick-borne encephalitis complex were ably reviewed by Dr. T. H. WORK
(New York). The full proceedings of the symposium will be published by the printing house of the Czechoslovak Academy of Sciences and this volume will be
an
authoritative summary of all present
knowledge of this important group of viruses. The organisers are to be congratulated on calling together the participants and drawing forth such a full and lively exchange of ideas. 4. See
Lancet, Oct. 29, 1960, p. 988.
Then indeed the " dissensions and bankruptcy " of which you warn us might well become a reality. Our seniors often tell us that there is no advantage to them from either course, and that they are only concerned to provide for the younger pathologists in whose hands the future lies. At the same time they tend, perhaps, to ignore the experience of most of those who discuss such matters with these younger pathologists, and find that they are mostly in favour of a College. The young men do not seem to be afraid of starting in a small way provided that they can feel genuinely independent and not a sort of appendage to another college. Their " image " of pathology is of a subject which is of real importance in its own right and which can therefore expect its own separate and
faculty ?
individual organisation. If we are to build surely for the future, independence is the only safe choice. When I have reached retiring age, I do not want my juniors to be able to say to me: " You and your colleagues made a fine mess of things in 1960. Here we are stuck in the College of Physicians where we are not really happy, but it will be very difficult to break away now. If you had only made the effort to form a College it would be well established by now. Did you have to choose the easy way? Couldn’t you see just a little way in front of your noses ?".
Yours, G. G.
Symposium TICK-BORNE ENCEPHALITIS VIRUSES FROM A CORRESPONDENT
THE Institute of Virology of the Czechoslovak Academy of Sciences acted as hosts to virologists from eleven different countries during a four-day symposium last month on the biology of viruses of the tick-borne encephalitis complex. The meetings were held in delightful surroundings at the House of Scientists at Smolenice, near Bratislava. Representatives from almost all the major groups working on this subject were present, and the symposium provided an unusual opportunity for workers from many different disciplines to pool information and exchange ideas in a common approach. In Britain, human infections with louping-ill virus do not present a serious public-health problem; but in Central Europe, Scandinavia, U.S.S.R., and India viruses of the tick-borne encephalitis group are The recent recognition of human a serious menace. infections with viruses of this group in Canada 1and the U.S.A.3 extends the area in which these viruses are known.
J. CASALS (New York) showed how the tick-borne viruses placed with yellow fever and some twenty other arthropodborne viruses into the serological group B on the basis of antigenic relationships. In the past, the tick-borne encephalitis viruses have been considered a homogeneous group in spite of wide differences in the disease patterns they produced in different parts of the world. Dr. D. H. CLARKE (New York) showed that they could be divided into six antigenic subgroups on the basis of haemagglutination inhibition tests with absorbed sera and by agar-gel precipitin tests. The six subgroups were represented by the classical far-eastern Russian spring-summer encephalitis (R.S.S.E.), louping ill, Omsk Dr.
were
1. McClean, D. M., Donaghue, W. L. Canad. med. Ass. J. 1959, 80, 708. 2. Casals, J. ibid. 1960, 82, 355. 3. Thomas, L. A., Kennedy, R.C., Eklund, C. M. Proc. Soc. exp. Biol., N.Y. 1960, 104, 355.
haemorrhagic fever, Kyasanur Forest disease,4 Malayan tickborne Langat virus, and Central European tick-borne encephalitis which included Czechoslovakian, Austrian, Finnish, Polish, Swedish, and Yugoslavian strains, as well as strains The recently described North from European U.S.S.R. American Powassan virus had not yet been examined by these
techniques. These antigenic differences were important because they explained the reported failure of R.S.S.E. vaccine to protect humans (Dr. P. N. BHATT, Poona) or mice (Dr. L. DANES, Prague) against infection with the virus of Kyasanur Forest disease. As in other branches of virology, tissue-culture techniques were gradually replacing older methods for the titration of viruses and for the detection of neutralising antibodies. The use of a plaque technique for the titration of tick-borne encephalitis viruses was described by Dr. J. S. PORTERFIELD (London) and was applied by Dr. V. MAYER, Dr. J. ZAVADA, and Dr. R. SKODA (Bratislava) to Central European strains. Dr. BHATT reported that chick fibroblast cultures were as satisfactory as mice for the primary isolation of Kyasanur Forest disease virus. Czechoslovak workers preferred a twostage process-primary isolation in tissue-culture cells which were later shown to be infected by virtue of their resistance to a challenge virus. Neutralising antibodies were detected by a metabolic inhibition test carried out in Hela cells (Dr. H. LiBIKovA and Dr. J. ViLCEK, Bratislava), by plaque inhibition (Dr. J. S. PORTERFIELD, London), or by the direct inhibition of cytopathic effect in Hela cells (Dr. E. MOLNAR, Budapest) or in pig kidney cells (Dr. D. MALKOvA, Dr. Z. MARHOUL, Dr. V. FRANKOvA, and Dr. V. CERNY, Prague). Vaccines derived from formalinised mouse brain had been used for many years in the U.S.S.R. (Prof. E. N. LEVKOVICH, Moscow, Prof. A. A. SMORODINSTEV, and Dr. V. I. ILYENKO, Leningrad) and formalin-inactivated louping-ill vaccine had been used to protect laboratory personnel (Dr. D. G. FF. EDWARD, Beckenham) and domestic animals (Dr. D. BLASCOVIC
and others, Bratislava). Attempts at producing a vaccine from virus grown in tissue culture were reported from Prague (Dr. R. BENDA and Dr. DANES), from Budapest (Dr. E. MOLNAR), and from the U.S.S.R. The major difficulty was to guarantee complete destruction of infectivity without at the same time reducing the antigenicity of the vaccine. There were many parallels with the poliomyelitis vaccine problems. A further important factor reported by Dr. G. D. ZASUKHINA (Moscow) was that virus grown in tissue culture with a deficient medium was less antigenic than virus grown in a rich medium. The maintenance of the tick-borne viruses in Nature is still not completely understood. The course of infection in an the laboratory mouse, was studied by experimental animal, Dr. P. ALBRECHT (Bratislava) in an elegant series of experiments based on the use of fluorescent antibody techniques. Other animals which may be infected in Nature include bats and, lizards (Dr. J. REHACTK, Dr. J. NosEK, and Dr. M. GRESIKovA, Bratislava), domestic ducks (Dr. E. ERNEK, Bratislava), and coots (Prof. H. A. E. VAN TONGEREN, Leiden). Much remains to be learned about the natural history of this group of viruses. Although the great majority of infections are transmitted by the bites of infected ticks, mechanical transmission by mosquitoes (Dr. Z. ZOTOWSKI and Dr. Z. WROBLEWSKA-MULARCZYKOWA, Warsaw) or fleas (Dr. K. HEYBERGER, Dr. A. SMETANA, and Dr. B. RosiCKY, Prague) may play some small part in the local spread of infection, and infection by the ingestion of milk from infected goats, sheep, and cattle is now well established. The many factors which influence the natural history of viruses of the tick-borne encephalitis complex were ably reviewed by Dr. T. H. WORK
(New York). The full proceedings of the symposium will be published by the printing house of the Czechoslovak Academy of Sciences and this volume will be
an
authoritative summary of all present
knowledge of this important group of viruses. The organisers are to be congratulated on calling together the participants and drawing forth such a full and lively exchange of ideas. 4. See
Lancet, Oct. 29, 1960, p. 988.