Total disc replacement alters the biomechanics of cervical spine based on sagittal cervical alignment: A finite element study.

Introduction: The correlation between cervical alignment and clinical outcome of total disc replacement (TDR) surgery is arguable. We believe that this conflict exists because the parameters that influence the biomechanics of the cervical spine are not well understood, specifically the effect of TDR on different cervical alignments. Methods: A validated osseo-ligamentous model from C2-C7 was used in this study. The C2-C7 Cobb angle of the base model was modified to represent: lordotic (-10°), straight (0°), and kyphotic (+10°) cervical alignment. The TDR surgery was simulated at the C5-C6 segment. The range of motion (ROM), intradiscal pressure, annular stresses, and facet loads were computed for all the models. Results: The ROM results demonstrated kyphotic alignment after TDR surgery to be the most mobile when compared to intact base model (41% higher in flexion-extension, 51% higher in lateral bending, and 27% higher in axial rotation) followed by straight and lordotic alignment, respectively. The annular stresses for the kyphotic alignment when compared to intact base model were higher at the index level (33% higher in flexion-extension and 48% higher in lateral bending) compared to other alignments. The lordotic model demonstrated higher facet contact forces at the index level (75% higher in extension than kyphotic alignment, 51% higher in lateral bending than kyphotic alignment, and 78% higher in axial rotation than kyphotic alignment) when compared among the three alignment models. Conclusion: Preoperative cervical alignment should be an integral part of surgical planning for TDR surgery as different cervical alignments may significantly alter the postsurgical outcomes.

Development of competitive inhibition ELISA as an effective potency test to analyze human rabies vaccines and assessment of the antigenic epitope of rabies glycoprotein.

The potency of all modern tissue culture human rabies vaccines is measured based on the National Institute of Health (NIH) potency test that is laborious, time-consuming, involves large test variations and requires sacrifice of large number of animals. To circumvent these limitations, several researchers and WHO expert working groups have discussed development of alternative in vitro methods to replace the NIH potency test. Although several immunochemical methods have been proposed to quantify rabies glycoprotein (G-protein) using multiple murine monoclonal antibodies, we report an In vitro competitive inhibition ELISA (CIA) method based on the use of a neutralizing rabies glycoprotein site III directed novel therapeutic human rabies monoclonal antibody (RAB1) that shows equivalence to the mice NIH potency test in recognition of neutralization site of the glycoprotein. In vitro potency testing of WHO 7th International Standard for rabies vaccine (IS) by CIA using RAB1 and In-house reference standard (IHRS) as a standard to assess its suitability for the assessment of validation parameters showed accurate and precise values with <15% coefficient variance. The method was validated using 5PL standard curve with linearity r2 > 0.98 and LLOQ of 0.125 IU/mL indicating sensitivity of the method. The method was found to be precise, robust and accurate to quantitate intact rabies glycoprotein in final vaccine and showed a strong correlation (Pearson's r = 0.81) with the NIH potency values of licensed Vero cell rabies vaccine. The CIA test using RAB1 was able to accurately quantitate degradation of rabies vaccine and assess loss in antigenicity of lyophilized and reconstituted liquid rabies vaccine under thermal stress conditions. The method was able to differentiate between potent and reduced potency vaccine samples. The new in vitro competitive inhibition ELISA method using RAB1 thus can be a valid alternative to the NIH test.

Development of a new purified vero cell rabies vaccine (Rabivax-S) at the serum institute of India Pvt Ltd.

INTRODUCTION: Rabies is a 100% fatal disease with significant disease burden in Asia and Africa but preventable with vaccines and immunoglobulins. There are very few WHO prequalified cell culture derived rabies vaccines available globally for use in humans. We have developed a new purified vero cell rabies vaccine (Rabivax-S) to meet this demand. Areas covered: In this review, we have described the detailed manufacturing process of Rabivax-S and summary of preclinical and clinical development based on the data generated in-house. Expert commentary: Rabivax-S has been developed on Vero ATCC CCL81 cells using Pitman Moore (PM3218) strain. Following all the GMP requirements the vaccine was tested in GLP toxicology studies. Further it underwent clinical trials in preexposure and postexposure settings and was found safe and immunogenic.

A randomized non-inferiority clinical study to assess post-exposure prophylaxis by a new purified vero cell rabies vaccine (Rabivax-S) administered by intramuscular and intradermal routes.

BACKGROUND: Rabies is a 100% fatal disease but preventable with vaccines and immunoglobulins. We have developed a new purified vero cell rabies vaccine (Rabivax-S) and evaluated its safety and immunogenicity in post-exposure prophylaxis by intramuscular (IM) and intradermal (ID) routes. METHODS: This was a randomized active-controlled non-inferiority study in 180 individuals (age 5years and above) with suspected rabies exposure (90 each with WHO Category II and Category III exposures). The participants received either Rabivax-S (1mL IM; five doses), Rabivax-S (0.1mL ID; eight doses) or purified chick embryo cell vaccine (PCEC, Rabipur®) (1mL IM; five doses). The IM doses were given on Day 0, 3, 7, 14 and 28 while the ID doses were given on days 0, 3, 7 and 28. Category III patients also received a human rabies immunoglobulin (HRIG) on Day 0. Adverse events (AEs) were recorded with diary cards till day 42. Rabies neutralizing antibody levels were measured on day 0, 7, 14, 28 and 42. RESULTS: In both the category II and III patients, the geometric mean concentration (GMC) ratios of Rabivax-S IM and Rabivax-S ID groups to PCEC IM were more than 1, thus proving the non-inferiority. GMCs were similar or higher in Rabivax-S groups at all the time points. Seroresponse against rabies (RFFIT titre⩾0.5IU/mL) was achieved in all participants. Mostly mild local and systemic adverse events were reported across the three groups and all resolved without sequelae. CONCLUSIONS: Rabivax-S was well tolerated and showed immunogenicity comparable to a licensed rabies vaccine by both IM and ID routes in post-exposure prophylaxis. Registry No.: CTRI/2012/11/003135.