Dog IgG (Fab) [FITC]

With the emergence of multidrug resistantSalmonellastrains, the development of anti-Salmonellavaccines is an important task. Currently there are no approved vaccines againstSalmonellaParatyphi A, the leading cause of paratyphoid fever. To fill this gap, oligosaccharides corresponding to theO-polysaccharide repeating units from the surface ofSalmonellaParatyphi A have been synthesized through convergent stereoselective glycosylations. The synthetic glycan antigen was conjugated with a powerful immunogenic carrier system, the bacteriophage Q beta. The resulting construct was able to elicit strong and long-lasting anti-glycan IgG antibody responses, which were highly selective towardSalmonellaParatyphi A associated glycans. The availability of well-defined glycan antigen enabled the determination that one repeating unit of the polysaccharide is sufficient to induce protective antibodies, and the paratose residue and/or theO-acetyl modifications on the backbone are important for recognition by antibodies elicited by a Q beta-tetrasaccharide conjugate. Immune sera provided excellent protection to mice from lethal challenge withSalmonellaParatyphi A, highlighting the potential of the synthetic glycan-based vaccine.

The screening for IgG subclass donor-specific antibodies (DSAs) in allograft recipients uses IgG1-4 subclass-specific monoclonal antibodies (mAbs) that should be mono-specific. The cross-reactivity discrepancies reported for IgG subclass-specific mAbs warranted a critical cross-reactivity pattern analysis of the IgG subclass-specific mAbs most commonly used to detect DSAs. We tested the reactivity of 2 anti-IgG1-, 3 anti-IgG2-, 1 anti-IgG3-, and 2 anti-IgG4-specific PE-conjugated mAbs against microbeads coated with IgG1-4 proteins separately. Each IgG subclass protein was coated at three densities on the beads (0.5, 1, and 2 pg of protein per 10(6) beads), and the PE-conjugated mAbs were titrated from 0.04 mu g/mL to 5 mu g/mL. The IgG subclass reactivity of the sample was acquired on the Luminex multiplex platform. Among the IgG subclass-specific mAbs, only the anti-IgG3 (clone: HP6050) mAb was mono-specific. All other mAbs tested were binding to IgG subclass proteins other than their respective immunogen, thereby being cross-reactive. IgG subclass cross-reactivity patterns were dependent on the concentration of both IgG subclass-specific mAbs and IgG1-4 protein targets coated onto the beads. With the current IgG subclass mAbs available, 3 of the 15 possible combinations of IgG1-4 subclass protein could be identified. While the remaining 12 unique combinations cannot be distinguished clearly, 6 groups that corresponded to two different unique combinations of IgG1-4 subclass protein could be identified. The dilution of serum samples and IgG subclass-specific mAbs, other than the anti-IgG3 (clone: HP6050), must be further optimized before their implementation in IgG subclass DSA screening in allograft recipients.