Both Lewis and Secretor Status Mediate Susceptibility to Rotavirus Infections in a Rotavirus Genotype-Dependent Manner

Background. The live oral rotavirus (RV) vaccines have shown a reduced efficacy in Africa. Recent in vitro studies have shown binding of the RV surface protein (VP4) to histo–blood group antigens (HBGAs) in an RV genotype–dependent manner, suggesting them to be putative receptors for RV. The diversity of HBGA phenotypes in different ethnic populations, combined with prevalence/absence of specific RV genotypes, led us to hypothesize whether the genetic variations in HBGAs in a population limit susceptibility to certain RV genotypes, plausibly leading to reduced vaccine efficacy.
Methods. Association between HBGAs status and susceptibility to RV P genotypes was investigated in children in Burkina Faso and Nicaragua. In total, 242 children with diarrhea in Burkina Faso and Nicaragua were investigated, 93 of whom were RV positive.
Results. In Burkina Faso, the P[8] RV strains (n = 27) infected only Lewis- and secretor-positive children (27/27; P < .0001), but no Lewis-negative children. In contrast, the P[6] strains (n = 27) infected predominantly Lewis-negative children (n = 18; P < .0001) but also Lewis-positive children, irrespective of their secretor status. The results from Nicaragua confirmed that all P[8]-infected children (n = 22) were secretor Lewis positive.
Conclusions. As VP4 of genotype P[8] is a component of current RV vaccines, our finding that Lewis-negative children are resistant to P[8] strains provides a plausible explanation for the reduced vaccine efficacy in populations with a high percentage of Lewis-negative individuals, such as in Africa. Furthermore, our findings provide a plausible explanation as to why P[6] RV strains are more common in Africa (read more)

Allo-antibody identification: a software approach!

Background : Unexpected allo-antibody identification is difficult serological test requiring in-depth knowledge of antibody behavior, identification rules, knowledge of zygosity of antigens and dosage phenomenon. Software which uses an algorithm based on characteristics of antibodies is now available to interpret specificity of allo-antibody. A study was undertaken to evaluate the effectiveness of one such software (Resolvigen) for antibody identification compared with manual antibody identification method.
Materials and Methods : The study was a retrospective observational study where 238 allo-antibody results were re-evaluated using Resolvigen software (Ortho Clinical Diagnostics, Johnson and Johnson, Raritan, NJ, USA) and agreement between manual and software approaches was studied. Resolvigen software was also evaluated for usefulness, ease of use and predicted future usage by administering investigators a questionnaire with Likert scale.
Results : Agreement between the results of manual and automated methods ranged from 98.6% for single antibody to 65% for two antibodies (p = 0.000). Resolvigen software came out as very useful, easy to use, and with high predicted future usage.
Conclusion : This study concludes that Resolvigen can either replace manual method or be used as adjuvant to routine manual method (read more)

Optical assay of erythrocyte function in banked blood

Stored red blood cells undergo numerous biochemical, structural, and functional changes, commonly referred to as storage lesion. How much these changes impede the ability of erythrocytes to perform their function and, as result, impact clinical outcomes in transfusion patients is unknown. In this study we investigate the effect of the storage on the erythrocyte membrane deformability and morphology. Using optical interferometry we imaged red blood cell (RBC) topography with nanometer sensitivity. Our time-lapse imaging quantifies membrane fluctuations at the nanometer scale, which in turn report on cell stiffness. This property directly impacts the cell's ability to transport oxygen in microvasculature. Interestingly, we found that cells which apparently maintain their normal shape (discocyte) throughout the storage period, stiffen progressively with storage time. By contrast, static parameters, such as mean cell hemoglobin content and morphology do not change during the same period. We propose that our method can be used as an effective assay for monitoring erythrocyte functionality during storage time (read more)