Table 1.

Infection of NIH 3T3 and NRK 52E cells expressing feline leukemia virus-C cell surface receptor (FLVCR)

Target Cell Titer (ffu/mL)
Amphotropic MuLV FeLV-A FeLV-B FeLV-C
FEA 2.6 × 105 1.4 × 107 1.8 × 104 2.4 × 105 
GP104C1 2.0 × 105 1  0 9.2 × 106 
NIH 3T3 2.9 × 105 0  0  0  
NIH 3T3(FLVCR) 3.4 × 105 0  3  47  
NRK 52E 6.8 × 105 <10  65  <10  
NRK 52E(vector)  7.2 × 105 <10  48  <10 
NRK 52E(FLVCR)  4.8 × 105 <10 <102 1.4 × 105 
Target Cell Titer (ffu/mL)
Amphotropic MuLV FeLV-A FeLV-B FeLV-C
FEA 2.6 × 105 1.4 × 107 1.8 × 104 2.4 × 105 
GP104C1 2.0 × 105 1  0 9.2 × 106 
NIH 3T3 2.9 × 105 0  0  0  
NIH 3T3(FLVCR) 3.4 × 105 0  3  47  
NRK 52E 6.8 × 105 <10  65  <10  
NRK 52E(vector)  7.2 × 105 <10  48  <10 
NRK 52E(FLVCR)  4.8 × 105 <10 <102 1.4 × 105 

FEA = feline embryonic fibroblasts; FeLV = feline leukemia virus; ffu = focus-forming unit; MuLV = murine leukemia virus. Titers were determined by alkaline phosphatase staining, which was performed 72 hours after exposure to LAPSN pseudotyped with amphotropic MuLV, FeLV-A, FeLV-B, or FeLV-C envelope proteins. Titers were averaged from three plates, from two infection studies. NIH 3T3(FLVCR) and NRK 52E(FLVCR) are cells that were transduced with MSCV(1.8 kb)neo then selected (×10d) in G418. NRK 52E(vector) are control cells that were transduced with MSCVneo then selected (×10d) in G418. The species of origin of FEA, GP104C1, NIH 3T3, and NRK 52E cells are cat, guinea pig, mouse, and rat, respectively.

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