FAMILY BOKRELIOTACEAE 



1245 



Other properties: Infectious particle 

 has sedimentation constant S20 = ca. 250 

 X 10~^' cm per sec. per dyne; usually 

 there is a secondary boundary at about 

 375 X 10~i^. Isoelectric point between 

 pH 4.8 and 5.1. Maximum absorption at 

 about 2750 A. Contains thj-mus nucleic 

 acid about 6.8 to 8.7 per cent ; maximum 

 absorption of nucleic acid at about 

 2630 A. 



Literature: Beard et al., Jour. Inf. 

 Dis., 65, 1939, 43-52; 69, 1941, 173-192; 

 Bryan and Beard, ibid., 65, 1939, 306-321 ; 

 Friedewald, Jour. Exp. Med., 75, 1942, 

 197-220; Hoyle, Jour. Path, and Bact., 

 50, 1940, 169-170; Kidd, Jour. Exp. Med., 

 68, 1938, 703-724, 725-759; 70, 1939, 583- 

 604; 71, 1940, 469-494; 74, 1941, 321-344; 

 75, 1942, 7-20; Kidd and Rous, ibid., 68, 

 1938, 529-562; 71, 1940, 813-838, Kidd et 

 al., ibid., 64, 1936, 63-77, 79-96; Rous and 

 Beard, ibid., 60, 1934, 701-722; 62, 1935, 

 523-548; Rous and Kidd, ibid., 67, 1938, 

 399-428; 71, 1940, 787-812; Rous et al., 

 ibid., 64, 1936, 385-400, 401-424; Schles- 

 inger and Andrewes, Jour. Hyg., 37, 

 1937, 521-526; Sharp et al., Proc. Soc. 

 Exp. Biol, and Med., 50, 1942, 205-207; 

 Shope, Jour. Exp.IMed., 58, 1933, 607-624 ; 

 65, 1937, 219-231; Syverton et al., ibid., 

 73, 1941, 243-248; Taylor et al., Jour. Inf. 

 Dis., 71, 1942, 110-114. 



8. Molitor myxomae (Aragao) comb, 

 nov. (Chlamidozoon myxomae Aragao, 

 Brazil-Med., 25, 1911, 471; name later 

 abandoned by its original author in favor 

 of Strongyloplasma myxomae Aragao, 

 Mem. Inst. Oswaldo Cruz. 20, 1927, 231 

 and 243. The name SanarelUa cnnicidi 

 Lipschiitz, Wien. klin. Wochenschr., 40, 

 1927, 1103, was based on the supposed 

 causative organism, defined as varying in 

 size between the size of chlamydozoa and 

 of large cocci ; it is not clear whether the 

 structures observed and named were 

 virus particles or not.) From New Latin 

 viyxoma, a kind of soft tumor, from nature 

 of induced lesion. 



Common names : M3^xoma virus, virus 

 myxomatosuvi . 



Hosts : LEPORIDAE—Oryclolagus 

 cuniculiis (L.), domestic rabbit. Ex- 

 perimentally, also Sylvilagus sp., cotton- 

 tail rabbit ; jack rabbit (once in many 

 trials); Lepus brasiliensis (resistant and 

 rarely infected). Also chick embiyo and 

 duck embryo. 



Insusceptible species : Lepus califor- 

 nicus Gray, black-tailed jack rabbit; L. 

 americanus Erxleben, varying hare ; Syl- 

 vilagus transitional is Bangs, cottontail; 

 horse, sheep, goat, cattle, dog (but one 

 reported infected), guinea pig, rat, 

 mouse, fowl, pigeon, duck, cat, hamster, 

 monkey; man (but some conjunctival 

 pain and swelling). 



Geographical distribution : South Amer- 

 ica (Brazil, Uruguay, Argentina), United 

 States (California). 



Induced disease : In domestic rabbit, a 

 disease {myxomatosis cuniculi) almost al- 

 waj's fatal at ordinary room temperatures 

 but not at 36 to 42° C, lesions fewer and 

 regressing after 6 to 8 days at these higher 

 temperatures in most animals. At ordi- 

 nary temperatures, nodules (edematous 

 tumors) in skin near eyes, nose, mouth, 

 ears, and genitalia; edema of eyelids; 

 conjunctivitis with purulent discharge 

 if skin around eyes is involved. Later 

 marked dj'spnea, stertorous breathing, 

 cyanosis, asphy.xia. Animals usually die 

 within 1 to 2 weeks of infection. Virus 

 enters bloodstream and invades nervous 

 system at random through walls of blood 

 vessels. Discharges from nose, eyes, and 

 the serous exudates from affected tissues 

 are infectious; urine and feces are not. 

 There are cytoplasmic inclusions in af- 

 fected epidermal cells. In chick em- 

 bryo, experimentally, intense inflamma- 

 tion, eventual impairment of circulation 

 and necrosis locally ; growth best if em- 

 brj^o is grown at 33 to 35° C and chilled 

 to 25° C for 12 to 18 hours before or after 

 inoculation, lesions being linear and asso- 

 ciated with capillaries in ectoderm; virus 

 infects and is recoverable from embryo 

 and depresses hatch. 



Transmission : By contact with dis- 

 eased rabbits or cages recently occupied 



