Filamentous Forms of Influenza Viruses 



263 



oval through short rods to filaments. It is only 

 Archetti (2) and Draganow (5) who give a more 

 comphcated description of the influenza virus, called 

 by Draganow N.W. -bodies. 



In this paper we are concerned with the observa- 

 tions on the influenza virus strains isolated in Poland 

 (in the Virology Department of the State Institute 

 of Hygiene headed by Prof. F. Przcsmycki) during the 

 influenza epidemics in the years 1953, 1954 and 1955. 



The virus strains were as follows: — 



The 1953 epidemic: 23 strains were isolated, from 

 which 14 were examined under the electron miscroscope. 

 The isolated strains belonged to the A-type and only 

 2 were established as belonging to A-prime-type (see (9) 

 where all methods are given). 



The 1954 epidemic: 12 strains were isolated, ail ex- 

 amined morphologically and found to belong to the A- 

 prime-type. 



The 1955 epidemic: 6 strains were isolated, all belong- 

 ing to B-type. The laboratory characteristics of the last 

 two epidemics are given in (10). 



The preparation of the specimen for the electron 

 miscroscope is described in the paper previously men- 

 tioned (6). 



One strain isolated from the 1954 epidemic (so-called 

 "LAK"), belonging to the A-prime type was examined 

 morphologically in more detail. Twenty passages were 

 performed and after each of them the strain was observed 

 under the electron microscope. The optimal passages 

 were 10 ^ or 5 x lO"*. 



The main result was that the isolated strains were 

 different morphologically. Some of them were fila- 

 mentous, other had round forms. 



The well-known strain PR8 (6) showed long and 

 filamentous forms but it ought to be considered as 

 a strain of round forms because the elementary round 

 bodies are prevalent here. One of the strains isolated 

 in 1953 showed exceptional concentration of long 

 filaments. This strain was a mixed one (obtained 

 from several washings), and it may be interesting 

 to note that the individual strains did not show any 

 or very little filamentous forms. The filaments have 

 thus become prevalent in the mixed strain. Another 

 strain of the same epidemic (so-called "Z.Z."), be- 

 longing to the A-prime type, can also be considered 

 as "filamentous'". 



Most of the strains from this epidemic belonged 

 to the A-type and they are of round forms. The long 

 filamentous forms were not present, but the charac- 

 teristic short beaded forms consisting of 3-4 beads 

 were also observed (fig. 1 ). 



All the 12 strains from the 1954 epidemic belonged 

 to the A-prime type and all should be considered 

 as filamentous. They showed a great variety of forms 

 (fig. 2). 



After several passages of the "LAK" strain the 

 concentration of the filaments decreased. 



All the strains isolated in the year 1955 belong to 

 the B-type. They consisted of elementary round 

 bodies only. 



Fig. 1. Strain K.M. Type A- 1953. Magnification 18,000. 

 hig. 2. Strain TM 1. Type A'- 1954. Magnification 1 1,000. 



In the "filamentous" strains the hemagglutination 

 titer of the infected allantois fluid was very low and 

 amounted from 1:40 up to 1:160. Although the 

 morphological pattern of the "LAK" strain after 

 the 1st and 1 5th passages was different, no diflerence 

 was established in the antigenic structure. 



The "filamentous" strains of the virus show strong 

 polymorphism. In addition to the round bodies, 

 there are also "transitory" forms (from spheres to 

 filaments) and complicated filamentous forms which 

 were called by Draganow N.W. -forms. These poly- 

 morphic bodies are characteristic only for the re- 

 cently-isolated strains and were observed on the 

 A-prime-type. All the B-type strains turned out to be 

 those of round forms. 



In my view the filamentous forms present an ear- 

 lier stage of the development of the virus which then 

 pass into elementary round bodies. 



The present work was carried out under the guidance 

 of Professor Przesmycki to whom I express my thanks. 



I should like to acknowledge the assistance of Mrs. 

 K. Zgorzelska and Dr. B. Malczewski in the preparation 

 of the virological samples. 



References 



1. Angulo, J. J., Arcli. Virusforscli. 4, 199 (1951). 



2. Archetti, L., Arch. Vinisforsch. 6, 29 (1955). 



3. Chu, C. M., Dawson, I., and Elford, W. J., Lancet 



256, 602 (1949). 



4. Donald, H. B., Isaacs, A., J. Gen. Microbiol. 11, 325 



(1954). 



5. Draganow, K. I., J. Gen. Biol. {U.S.S.R.) 17, 13 (1956). 



6. Feltynowski, a. and Zych, Z., Med. Doswiadc:alna i 



Mil<robiol. 5, 423 (1953). 



7. HoYLE, L., /. Hyg. Camh. 48, 277 (1950). 



8. MosLEY, V. M. and Wvckofe, R. W. G., Nature 157, 



263 (1946). 



9. Przesmycki, F. et al., Med. Do.swiadczalna i Mi/<robiol. 



6, 241 (1954). 



10. Przesmycki, F. er al.. Bull. Acad. Polon. Sci. C\. II, 4, 



111 (1956). 



11. Wyckoef, R. W. G., Nature 168, 651 (1951). 

 12 — J. Immunol. 70, 187 (1953). 



