In vivo EIAV infection of ELR1/eCT1 mice with EIAV. (A) The plasma viral loads of EIAV in ELR1/eCT1 and wild-type mice (n = 8 for each group) were measured using quantitative real-time RT-PCR for the gag gene at 0, 2 and 4 weeks after intraperitoneal injection with 104 TCID50 EIAVDLV34. *, P < 0.05; **, P < 0.01, using Students t test, between the ELR1/eCT1 mice groups at 0, 2 and 4 weeks after intraperitoneal injection. (B) Copies of the EIAV genomic RNA in six organs (intestine, spleen, lymph nodes, kidney, lung and liver) from ELR1/eCT1 mice and wild-type mice (n = 8 for each group) were measured after intraperitoneal injection with EIAVDLV34 for four weeks. *, P < 0.05; **, P < 0.01, using Student’s t test. (C) and (D) RNA-RNA fluorescence in situ hybridization (FISH) of spleen and lymph node sections from ELR1/eCT1 and wild-type mice was performed after intraperitoneal injection with EIAVDLV34 for four weeks. The existence of EIAV was detected through the hybridization of viral genomic RNA with EIAV-specific RNA probes that were labeled with digoxigenin (DIG) and then stained with anti-DIG-fluorescein, Fab fragments (green fluorescence). The cell nuclei were stained with 4′,6-diamidino-2-phenylindole (DAPI) (blue fluorescence). (E) Immunohistochemistry was performed to detect EIAV proteins in the spleen and lymph nodes from ELR1/eCT1 and wild-type mice after intraperitoneal injection with EIAVDLV34 for four weeks. The tissue sections were stained with a monoclonal antibody recognizing the EIAV p26 antigen and a horseradish peroxidase (HRP) conjugated anti-mouse IgG. The cells infected with EIAV are shown as brown (typical cells are indicated by arrows).