Fig 1.
Host-specific patterns of relative MAT antibody titers detected against five Leptospira serovars (Pomona, Djasiman, Autumnalis, Bratislava, and Icterohaemorrhagiae) when the infecting serovar is L. interrogans serovar Pomona.
Each plot shows the relative antibody titer levels (antibody titer against one serovar divided by the highest antibody titer detected against any serovar in the 5-serovar MAT panel run for that sample) for California sea lions (left; purple; n = 137), island foxes (middle; cyan; n = 59), and spotted skunks (right; green; n = 4). The shaded regions on each plot are a representative subsample of overlaid polygons for each species (nCSL = 59; nfox = 59; nskunk = 4), each linking the values for an individual sample. The continuous black line shows the relative antibody titer level for each sample (sample titer/maximum sample titer) averaged across all samples for each serovar for that species. The dashed black lines and the percentages associated with each serovar indicate the proportion of samples for which that serovar has the highest titer out of all serovars in that individual’s panel, regardless of the actual titer. These numbers add up to more than 100% for sea lions and foxes, since multiple serovars can have the highest titer for any given sample (e.g., a particular individual could have highest titer of 1:6400 against both Pomona and Icterohaemorrhagiae).
Fig 2.
Pairwise antibody titer levels against Leptospira interrogans serovars Pomona, Djasiman, Autumnalis, Bratislava, and Icterohaemorrhagiae in three host species.
Each plot shows the pairwise endpoint MAT titer levels (log2 dilutions) for California sea lions (purple), island foxes (teal), and spotted skunks (green), all presumed to be infected with the same strain of serovar Pomona. The colors aggregate in a distinct pattern, showing that the serovar reactivity pattern is affected by the host species and that absolute titer magnitude differs among species. The black diagonal line corresponds to perfect equivalence between different serovars. Jitter has been added to the points to aid visualization. Inset: differences in MAT titer magnitude against each serovar among host species.
Fig 3.
Selected example of longitudinal antibody titer dynamics in a Channel Island fox infected by L. interrogans serovar Pomona.
The top panel shows antibody titers against L. interrogans serovars Pomona (black solid line) and Autumnalis (blue dashed line) from longitudinally collected serum samples from one fox. The bottom panel indicates the PCR test result from urine samples taken at the same time as serum collection.
Fig 4.
Comparison of antibody titer results for fox serum samples evaluated at three testing laboratories.
Island fox serum samples (n = 46) were tested in three different certified testing laboratories. The MAT antibody titers (log2 dilutions) for serovars Pomona and Autumnalis are shown. All Pomona titers were run to endpoint dilution. In Panel A, open circles indicate non-endpoint Autumnalis titers at 1:6400 (log MAT titer 7) whereas open squares denote samples that were positive against serovar Autumnalis at 1:100, but no dilutions were performed. Jitter has been added to the points to aid visualization. Panel B represents the difference in antibody titer magnitude for a subset (n = 32) of samples that were run to endpoint for serovars Autumnalis and Pomona at all three laboratories.