All females of both groups had ovulated after return to estrus on the basis of progesterone levels in plasma and the examination of ovaries after slaughter. The mean ovulation rate after return to estrus was 13 ± 1.1 in the IFN group, and 14 ± 2.2 in the control group. The difference was not significant (p > 0.37). The overall ovulation rate (14 ± 1.8) was similar to that observed during treatment (13 ± 4.4, p > 0.25). Thus, no carryover effect of the IFN treatment on the ovarian activity was observed.
Interferon Titer in Peripheral Blood
Blood plasma samples from all 15 gilts on Day 14 post-estrus (day of maximal IFN infusion) and Day 15 postestrus (24 h after the last injection) were analyzed for the presence of IFN, mainly to test the perfusion. All samples were assayed with the two available tests: ELISA, which specifically detects IFN–y, and the antiviral assay, which detects the total activity of both IFN species.
Plasmatic ELISAs were negative, except for one gilt at Day 14, with a titer of 15 ng/ml. This gilt was, however, a control. Upon slaughter, an infection with an abscess on the right horn was detected, which probably was the cause of this transient IFN-7 titer in the blood. This indicates 1) that, as in pregnant uteri, there was a complete barrier effect of the uterine wall, as far as IFN-7 is concerned; and 2) there was neither significant loss of perfusate nor major effraction of the blood vessels upon injection of IFNs through the catheter. flovent inhaler
No significant antiviral activity (>20 IU/ml) was found in any of the blood samples. A weak “IFN-like” activity was found in all plasmas, whether from controls (7.8 ±1.6 IU/ml) or from treated (6.6 ± 1.88 IU/ml) gilts. This confirms a previous unpublished observation of a “background” anti-VSV activity in most adult pig sera, which is not neutralized by anti-IFN antibodies.