Three of four animals of Group B had significantly higher serum IgG and IgA titres following intravaginal administration of gp140 (IgG P = 0.05, IgA P = 0.039; paired t test) ( Fig. 2). In GSK3 inhibitor contrast, none of the animals of Group C had increased serum antibody following intravaginal administration ( Fig. 3). As would be expected, titres of serum IgG and IgA were significantly higher at the time of intravaginal immunisation in animals of Group C that had received 3 intramuscular immunisations compared to those of Group B (IgG gmt: 18,197 versus 649, P < 0.001; IgA gmt: 1972 versus 173, P = 0.027; t-test). Results for mucosally detectable

antibody were more difficult to interpret given the variability seen at different sampling times and on some occasions between cervical and vaginal PF-02341066 molecular weight samples taken at the same time. All animals of Group B appeared to respond following intravaginal immunisation, including E49 that did not show a boost in serum antibody.

This animal was unusual in that serum IgA titres were similar to IgG titres and IgA titres were higher than IgG titres in cervical and vaginal samples. Interestingly, total IgA concentrations were not elevated in cervical or vaginal secretions from this animal (Table 2) and significant haemoglobin contamination was only seen at Day 126, when titres of anti-gp140 IgA in and the cervical sample had declined and were below the limit of detection in the vaginal sample. Mucosally-detected antibody responses were seen in all animals of Group C following intramuscular immunisation. In most instances antibodies appeared following the second immunisation, subsequently waned and recovered following a further intramuscular exposure. For logistical reasons it was not possible to obtain mucosal samples immediately before intravaginal

immunisation; however, antibodies were detected locally in all animals after the cycle of intravaginal immunisation but peak titres were not elevated. Overall, 3 intramuscular immunisations before intravaginal boosting conferred no advantage over a single intramuscular immunisation in terms of either the frequency or titre of antibody response detected in cervical and vaginal samples. Overall in Groups C and D both IgG and IgA anti-gp140 antibody titres were higher in cervical fluids than vaginal fluids, with median titres of IgG of 80 and 24 and of IgA of 103 and 54 in vaginal and cervical samples respectively (Fig. 4). This difference however only reached statistical significance for IgG. Comparison for individual animals showed cervical samples to contain higher titre antibody than vaginal samples on 76% and 85% of occasions tested for IgG and IgA respectively.