TABLE 3.
Virological and serological markers of FIV infection in FIV-RBC-immunized and mock-immunized cats at the time of rechallenge and at selected times thereafter
| Cat category and no. | Presence of marker or no. of infected cells at rechallenge time (mo):
|
|||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 0
|
1
|
3
|
6
|
|||||||||
| PCRa | VIb | PCR | VI | Sc | PCR | VI | S | PCR | VI | Viral loadd | S | |
| BSA-RBC immunized | ||||||||||||
| 442 | + | − | + | + (10) | − | + | + (15) | + | + (1,110) | + (28) | 10 | + |
| 449 | − | − | − | + (14) | − | − | + (15) | + | − | + (28) | 1 | + |
| FIV-RBC immunized | ||||||||||||
| 2910 | − | − | − | − | − | − | − | − | − | − | − | |
| 2911 | − | − | + | + (15) | − | + | + (15) | − | + (4,440) | + (14) | 10 | − |
| 2923 | − | − | − | + (7) | − | + | + (7) | + | + (830) | + (14) | 102 | + |
| 2926 | − | − | − | + (7) | − | + | + (7) | + | + (660) | + (14) | 102 | + |
PBMC were examined for proviral FIV gag sequences by nested PCR. Values in parentheses at 6 months indicate the proviral load present in 1 μg of PBMC DNA as assessed by competitive PCR.
VI, virus isolation by coculture with MBM cells. Values in parentheses indicate days of incubation at the time cultures first became positive.
S, serology. Sera were tested in an ELISA for IgG antibody to purified and disrupted FIV. +, antibody titer at least fourfold higher than that at the time of challenge; −, antibody titer not significantly different from that at the time of challenge.
At this time, PBMC were also examined for infectious virus load by quantitative isolation. Results are expressed as numbers of infected cells per 106 PBMC.