FAMILY BORRELIOTACEAE 



1231 



Path., 7, 1931, 209-222; C. E. Woodruff, 

 ibid., 6, 1930, 169-174; C. E.Woodruff, 

 and Goodpasture, ibid., 5, 1929, 1-10; 

 6, 1930, 713-720. 



2. Borreliota variolae (Lipschiitz) 

 Goodpasture. (Sirongyloplasma variolae 

 Lipschiitz, in KoUe, Kraus and Uhlen- 

 huth, Handbuch der pathogenen Mikro- 

 organismen, 3 Aufl., 8, 1930, 317; Good- 

 pasture, Science, 77, 1933, 121.) From 

 New Latin variola, smallpox. 



Common names: Variola virus, small- 

 pox virus. Most studies of this virus 

 have been concerned with the vaccinia 

 strain ; see Strains below. 



Hosts : Man, cow and rabbit are sus- 

 ceptible to strains that appear especiallj' 

 adapted to them (see Sirai7is below). 

 Experimentally, also chicken (and chick 

 embryo); Chrysemys marginata, turtle; 

 guinea pig, horse, pig; Macaca miilatta 

 (Zimmermann), rhesus monkey; M. irus, 

 cynomolgus monkey; orang-outang; Ma- 

 cacus fuscatus. 



Geographical distribution: Nearly 

 world-wide, except where excluded bj' 

 isolation or protective vaccination. 



Induced disease : In man, mild to 

 severe smallpox, sometimes with pocks 

 few and discrete but often with pocks 

 numerous and coalescing; onset sudden, 

 6 to 22 days (average 12) after infection; 

 headache, vomiting, fever, often rashes 

 on bodj' before appearance of the specific 

 eruption, bright red spots becoming vesic- 

 ular and eventually pustular; the pocks 

 are commonest on face, forearms, wrists, 

 palms of hands, and soles of feet ; pustules 

 gradually become flattened scabs and 

 drop off, leaving no scar if superficial and 

 not secondarily infected; in hemorrhagic 

 smallpox there are numerous hemorrhages 

 into the skin and mortality is high, death 

 often preceding formation of pustules; 

 severity of disease and mortality roughly 

 proportional to the amount of eruption 

 on the face. 



Transmission : By contact with in- 

 fected individuals or contaminated ar- 

 ticles; perhaps by droplet infection, 



obvious primary lesions characterizing 

 experimental transmission by scarification 

 but not natural spread. 



Serological relationships : Hyperim- 

 mune calf serum neutralizes virus. Neu- 

 tralization depends on an antibody not 

 involved in agglutination and precipita- 

 tion. Antivaccinial serum gives com- 

 plement fixation in the presence of variola 

 virus. One agglutinogen (L) labile at 

 56° C, one (S) stable at 95° C; both are 

 parts of a single protein but can be de- 

 graded independently; chymotrypsin de- 

 stroj's activity of S, not L. Increasing 

 neutralization in immune serum and virus 

 mixtures in vitro with progressive incuba- 

 tion; partial reactivation on simple dilu- 

 tion. Antivaccinial sera agglutinate Pas- 

 chen bodies of vaccinia but not Borrel 

 bodies of fowl pox ; anti-fowl -pox sera ag- 

 glutinate Borrel but not Paschen bodies. 

 No cross reactions with herpes virus. 



Immunological relationships : In vac- 

 cinia-immune swine, protective sub- 

 stances pass via colostrum, conveying 

 passive immunity to young for 2 to 3 

 months after birth. In man, immunity 

 against variola virus is conferred by ear- 

 lier infection with vaccinia strain. In 

 hen, previous infection with fowl-pox 

 virus does not immunize with respect to 

 vaccinia virus. 



Thermal inactivation : At 55° C in 20 

 minutes. 



Filterability : Passes Berkefeld V, not 

 Mandler, filter. 



Other properties: Density about 1.16. 

 Sedimentation constant 5000 X lO^i^ 

 (corrected to water at 20° C). Retains 

 activity in glycerine best at pH 7.0. 

 0.1 per cent gelatin delays spontaneous in- 

 activation at 5 to 10° C. Withstands 

 absolute alcohol, ether, acetone, and 

 petroleum ether 1 hour in dry samples at 

 4° C without decrease in activity. Inac- 

 tivated without disruption by sonic vi- 

 brations of about 8900 cycles per second. 

 Diameter estimated as 125 to 175 milli- 

 microns by filtration; 236 to 252 milli- 

 microns by ultracentrifugation. Elec- 

 tron micrographs show limiting surface 



