196 



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556. BENNETT, I, L., WAGNER, R. R. and LEQUIRE, V, S. 



The production of fever by Influenzal viruses, II. Tolerance 

 In rabbits to the pyrogenlc effect of Influenzal viruses 



J. Exper. Med, 90:335-347, 19^9 



Prior Injection of certain strains of viruses (PR8 strain of In- 

 fluenza A, Lee strain of Influenza B and "B" strain of NDV) con- 

 ferred tolerance. In the rabbit, to the pyrogenlc effects of 

 homologous virus as well as some degree of protection against 

 the lymphopenlc action of such virus. The period of tolerance 

 extended, on the average, over 11 days. The protective effect 

 of heated virus was lost when hemagglutinins were destroyed. 

 It appears to be Independent of specific antibody formation. 

 No cross tolerance was demonstrable between bacterial pyrogens 

 and viruses. Prevention of fever by antipyretic substances did 

 not Interfere with protective Influence of previous condition- 

 ing. No modification of the reactions could be secured with 

 reticuloendothelial blockade. 



557. BENNETT, I. L., WAQNER, R., and LEQUIRE, V. S. 



Pyrogenlclty of Influenza virus In rabbits 



Proc. Soo. Exper. Biol. & Med. 71:132-133, 19^9 



One ml. of chorlo-allantolc fluid from Infected embryos pro- 

 duced a rise In temperature In the rabbit; doses as small as 

 0.25 ml. also produced fever of a low degree. The rise In temp- 

 erature began about li to 2 hours after Injection of fluid se- 

 cured from PR-8 Infected embryos, reached a peak of 3 to 4 de- 

 grees P. above baselines In four hours, then fell to normal 

 levels. When normal chorlo-allantolc fluid or fluids freed from 

 virus particles through centrlfugatlon were Injected, no fever 

 resulted; the virus re-suspended In physiologic saline solution 

 again produced temperature elevations. Homologous Immune serum 

 neutralized the virus responses. Exposure to heat destroyed 

 hemagglutinin titers and rendered preparations non-pyrogenio. 

 Unlike heat-stable pyrogens the fever element of both PR8 in- 

 fluenza virus and the Lee strain B were destroyed by temperatures 

 above 62° C. The Lee strain required temperatures considerably 

 higher for complete destruction of the pyrexlal material. Tol- 

 erance to the substance was quickly attained but lost again In 

 eleven days. Antibody titers Increased In the period. 



558. BHARUCHA, K. 



Pyrogen and Its prevention 



Indian J. Med. Scl, 3:349-350, I949 



