FAMILY ERRONACEAE 



1249 



damage ; in mouse inoculated iutranasally , 

 virus enters blood and reaches the olfac- 

 tory bulb where it multiplies to a high 

 concentration before infecting the re- 

 mainder of the brain and the rest of the 

 nervous system ; tends to disappear from 

 the blood after sickness begins but per- 

 sists in the brain until death from 

 encephalitis. In chick embryo, after 

 inoculation of chorioallantoic membrane, 

 edema and opacity spreading from site 

 of inoculation on membrane of 10-day 

 embryo ; in 12-day eggs, discrete primary 

 lesions, sometimes with secondary lesions 

 surrounding them on the inoculated mem- 

 brane ; embryo dies in about 6 days, after 

 showing jaundice, edema, mottling of the 

 liver with necrosis ; virus regularly in 

 blood. In monkey, Macacus rhesus, 

 progressive cerebellar ataxia ; encephalo- 

 myelitis with involvement and massive 

 destruction of Purkinje cells in the cere- 

 bellum. 



Transmission : By ticks, Rhipicephalus 

 appendiculatus and Ixodes ricinus (IXO- 

 DIDAE). In Rhipicephalus appendicu- 

 latus, the larva or nymph becomes in- 

 fected ; only a few individuals retain virus 

 until the adult stage ; virus does not pass 

 through the egg. Non-viruliferous ticks 

 do not acquire virus by feeding with 

 infective ticks on immune animals. Ex- 

 perimentally, by intracerebral or intra- 

 peritoneal injection in mouse ; by intra- 

 nasal instillation in rat, mouse, and 

 monkey. 



Serological relationships : Complement 

 fixation and neutralization tests show 

 cross reactions with Russian spring- 

 summer encephalitis virus, but immune 

 serum against louping-ill virus is only 

 partially effective in neutralizing the 

 spring-summer encephalitis virus. 



Immunological relationships: Mice are 

 protected against louping-ill virus by 

 vaccination with non-virulent spring- 

 summer encephalitis virus but protection 

 is less effective than for the homologous 

 virus. No cross immunity with respect 

 to Rift Valley fever virus or poliomyelitis 

 virus in Macacus rhesus, but immunity 



with respect to reinfection by louping-ill 

 virus has been demonstrated. 



Thermal inactivation : At 58° C in 10 

 minutes. 



Filtefability : Passes Berkefeld V, N, 

 and W filters. 



Other properties : Viable in broth fil- 

 trates after storage at 4° C and pH 7.6 

 to 8.5 for 70 days. Particle diameter, cal- 

 culated from ultrafiltration data, 15 to 20 

 millimicrons. 



Literature : Alexander and Neitz, Vet. 

 Jour., 89, 1933, 320-323; Onderstepoort 

 Jour. Vet. Sci. and Anim. Industr., 5 

 1935, 15-33; Alston and Gibson, Brit 

 Jour. Exp. Path., 1£, 1931, 82-88; Burnet 

 Jour. Path, and Bact., 4.2, 1936, 213-225 

 Brit. Jour. Exp. Path., 17, 1936, 294-301 

 Burnet and Lush, Austral. Jour. Exp 

 Biol, and Med. Sci., 16, 1938, 233-240 

 Casals and Webster, Science, 97, 1943 

 246-248; Jour. Exp. Med., 79, 1944 

 45-63; Elford and Galloway, Jour. Path 

 and Bact., 37, 1933, 381-392; Findlay 

 Brit. Jour. Exp. Path., 13, 1932, 230-236 

 Fite and Webster, Proc. Soc. Exp. Biol, 

 and Med., 31, 1934, 695-696; Galloway 

 and Perdrau, Jour. Hyg., 35, 1935, 339- 

 346; Hurst, Jour. Comp. Path, and 

 Therap., U, 1931, 231-245; M'Fadyean, 

 Jour. Comp. Path, and Therap., 7, 1894, 

 207-219; 13, 1900, 145-154; Pool et al., 

 ibid., 43, 1930, 253-290; Rivers and 

 Schwentker, Jour. Exp. Med., 59, 1934, 

 669-685; Schwentker et al., ihid., 57, 

 1933, 955-965. 



2. Erro silvestris spec. nov. From 

 Latin silvestris, of the forest, in reference 

 to incidence of the induced disease almost 

 exclusivel}' in those who enter forest 

 lands. 



Common names : Spring-summer en- 

 cephalitis virus, forest spring encephalitis 

 virus. 



Hosts: Man; probably cattle, horse; 

 Euiamias asiaticus orientalis, Evotomys 

 rufocanus arsenjevi. Experimentally, 

 also white mouse, Macacus rhesus, birds, 

 goat, sheep, Microius michnoi pelliceus 

 Thom., Cricetuhis furunculus. 



