TABLE 1.

Borreliacidal activity of OspB antibodies against B. burgdorferi N40^a

Antibody	No. of viable B. burgdorferi cells
	24 h	48 h
Control (no addition)	100	100
NRS	92 ± 4.5	104 ± 6
NRS-F(ab2)	93 ± 10	97 ± 13
OspB-F(ab2)	102 ± 8.5	99 ± 26
MAb B22	99 ± 19	96 ± 18
MAb B27	98 ± 6.7	90 ± 5.5
Human B. burgdorferi antiserum	10 ± 9	0

^aSpirochetes were incubated in BSK medium in the absence (control) or presence of normal rabbit serum (NRS), F(ab₂) fragments prepared from normal rabbit serum [NRS-F(ab₂)], polyclonal anti-OspB serum [OspB-F(ab₂)], OspB MAb B22 or B27 or a borreliacidal serum from a patient with Lyme disease. The numbers of spirochetes were assessed by dark-field microscopy after 24 and 48 h and are expressed relative to controls without antibody or serum treatment. Data represent the mean numbers of spirochetes remaining viable after treatment (means ± standard errors from three independent experiments). Differences between the control and normal rabbit serum as well as OspB antibodies or F(ab₂)-treated samples were not statistically significant (Student's t test).