TABLE 1.

Phenotypic comparisons between F. tularensis variants

Strain	Colony Morphology	LD50a	Intramacrophage Survivalb	Serum Sensitivity	Protective vs. Schu S4 Challengec	O-Antigen	Reference
LVS	Large, blue, smooth	<10	Survives well	Resistant	Protective	Complete	29,30
LVSG	Small, gray, smooth	>103	Defective	Sensitive	Not protective	Complete	31, J. Gunn, Unpublished Observation
LVSGD	Small, gray, smooth	>105	Defective	Sensitive	Not protective	Absent	32
LVSGT	Large, transparent, gray?	ND	Defective	Sensitive	ND	Present but Reduced Length	J. Cannon, Personal Communication
Schu S4	Large, blue, smooth	<10	Survives well	Resistant	NA	Complete	27,28
Schu S4NS	Small, non-smooth, gray	107	ND	ND	Not protective	ND	27

^aRoutes of delivery of the reported LD₅₀s are as follows: LVS (i.p.), LVSG (i.n.), LVSG^D (s.q.), Schu S4 (i.p.), Schu S4^NS (i.p.).

^bMacrophages (primary or cell lines) used are as follows: LVS (rat, mouse, and human primary or cell lines), LVSG (rat, mouse [reduced proliferation is to a lesser extent than in other macrophage types], and human primary or cell lines), LVSG^D (J774.1), LVSG^T (THP-1).

^cThe route of administration is as described under the LD50 column, and the Schu S4 was via the same route as the variant strain. The dosages of Schu S4 were variable but the results reported in this table are accurate for 10–100 LD50S as the dose.