A double-blind, randomized, controlled, multi-center safety and immunogenicity study of a refrigerator-stable formulation of VARIVAX®.

OBJECTIVE: VARIVAX® (varicella virus vaccine, live Oka/Merck, Merck & Co., Inc., Kenilworth, NJ, USA) was originally licensed as a frozen formulation. A refrigerator-stable formulation of VARIVAX was subsequently developed to allow for increased availability of the product around the world. The objective of this study (V210-051) was to demonstrate that the safety, tolerability and immunogenicity profile of the refrigerator-stable formulation of VARIVAX was similar to the frozen formulation. METHODS: In this double-blind, randomized, multicenter study, healthy 12- to 23-month-old children with negative vaccination and clinical histories for measles, mumps, rubella, varicella, and zoster were vaccinated with either a refrigerator-stable formulation of VARIVAX (at two dosage levels; 8000 PFU [N = 320] or 25,000 PFU [N = 315]) or the frozen formulation of VARIVAX (10,000 PFU, N = 323) given concomitantly with M-M-RII® (measles, mumps, and rubella virus vaccine live, Merck & Co., Inc., Kenilworth, NJ, USA). Children were followed for 42 days after vaccination for adverse experiences. Immunogenicity was evaluated 6 weeks after vaccination. RESULTS: The refrigerator-stable formulation of VARIVAX was generally well tolerated. The incidence of adverse experiences was similar between all three groups. No vaccine-related serious adverse experiences were reported with any of the vaccine formulations. The immune response (percentage of subjects with varicella antibody titers ≥5 gpELISA units) for both refrigerator-stable formulations of VARIVAX at 6 weeks postvaccination was similar to that of the frozen formulation. Administration of either refrigerator-stable formulation of VARIVAX with M-M-RII yielded seroconversion rates and GMTs for measles, mumps and rubella that were comparable to those achieved after administration of the frozen formulation of VARIVAX with M-M-RII. CONCLUSION: The safety, tolerability, and immunogenicity profile of the refrigerator-stable varicella vaccine was similar to that of the frozen formulation.

Comparative analyses of the 9 glycoprotein genes found in wild-type and vaccine strains of varicella-zoster virus.

The complete DNA sequences of wild-type and vaccine strains of varicella-zoster virus have been published and listed in GenBank. In this comparative genomic analysis, the sequences of the 9 glycoprotein open reading frames (ORFs) were compared. They included gE (ORF68), gI (ORF 67), gC (ORF14), gH (ORF37), gL (ORF60), gB (ORF31), gK (ORF5), gM (ORF50), and gN (ORF8 or ORF9A). After realignment on the basis of newer data, the corrected gB sequence was lengthened to include 931 residues. The data showed that there were glycoprotein polymorphisms that differentiated North American/European strains from Japanese strains-for example, an additional ATG codon in the gL of all Oka strains. Also, there were a small number of coding single-nucleotide polymorphisms present only in glycoproteins of vaccine strains. Because these changes were highly conserved, the structure of the glycoprotein was unlikely to be altered.

Generation of a recombinant Oka varicella vaccine expressing mumps virus hemagglutinin-neuraminidase protein as a polyvalent live vaccine.

We constructed a recombinant varicella-zoster virus (VZV) Oka vaccine strain (vOka) that contained the mumps virus (MuV) hemagglutinin-neuraminidase (HN) gene, inserted into the site of the ORF 13 gene by using the bacterial artificial chromosome (BAC) system in Escherichia coli. Insertion of the HN gene into the VZV genome was confirmed by PCR and Southern blot. The infectious virus reconstituted from the vOka-HN genome (rvOka-HN) had a growth curve similar to the original recombinant vOka without the HN gene. The mumps virus HN protein expressed in rvOka-HN infected cells was expressed diffusely in the cytoplasm, and modification of the protein was similar to that seen in MuV-infected cells. Electron microscopic examination of infected cells revealed that HN was expressed on the plasma membrane of the cells but not in the viral envelope, suggesting that the tropism of rvOka-HN would be unchanged from that of the original vOka strain. Immunization of guinea pigs with rvOka-HN-induced VZV- and HN-specific antibodies. Interestingly, the induced antibodies had a strong neutralizing activity against virus-cell infections of both MuV and VZV. Therefore, the novel varicella vaccine expressing MuV HN protein is suitable as a polyvalent live attenuated vaccine against VZV and MuV infections.

Development of a varicella virus vaccine stabilizer containing no animal-derived component.

Various stabilizers containing no animal-derived components were assessed for their efficacy in stabilizing live attenuated varicella virus under various storage temperatures. Stabilizers containing carrageenan, soy protein hydrolysates, or sucrose had a satisfactory performance to maintain infectivity of the cell-free virus when compared to control stabilizer containing animal-derived gelatin/gelatin hydrolysate.

Development of liquid chromatographic method for the analysis of kanamycin residues in varicella vaccine using phenylisocyanate as a derivatization reagent.

A liquid chromatographic method for the determination of the aminoglycoside kanamycin in varicella vaccine is described. Kanamycin sulfate was derived with phenylisocyanate (PIC) and triethylamine for 10 min at 70 degrees C and chromatographed on a alkylamide-bonded column, Suplex pKb-100. A derivative of kanamycin sulfate was attached to four phenylisocynato groups and that molecular mass was confirmed with liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS). The kanamycin-PIC derivative was found to have a retention time of 11.7 min using an eluent composed of 40% acetonitrile in water at 1.2 ml/min column flow-rate. Detection was at a wavelength of 240 nm. Recoveries ranging from 97.5 to 99.8% were found. The correlation coefficient was greater than 0.9998 over the range between 10 and 100 microg/ml. The method precision of within-day assay showed a 0.5 to 4.0% coefficient of variation (n = 5) ranging from 10 to 70 microg/ml of kanamycin concentration levels. Kanamycin-PIC derivative in reaction solution was stable for 24 h at room temperature. A simple and efficient method for the analysis of the kanamycin in varicella vaccine was developed and validated.

A varicella vaccine stable at 5 degrees C.

Varicella-Zoster virus (VZV), which causes Chicken Pox and Zoster, belongs to the Herpes viridae family [1, 2]. The virus is strongly cell dependent and its in vitro stability is very low. Following Takahashi's work, we have developed and prepared a vaccine with the OKA strain virus in the Japanese stabilizer. To improve the stability of the virus in a freeze-dried form, we have finalized a new formulation of stabilizer, called V 15-1. This stabilizer is a protein-free solution with defined contents of amino acids, salts and sugars. Comparative stability studies between the Japanese stabilizer and V 15-1 have been performed at different temperatures. We have demonstrated good stability for two years at + 5 degrees C and at + 25 degrees C and + 37 degrees C for the vaccine in freeze-dried form. We have also found a good stability of this vaccine at + 5 degrees C and + 25 degrees C after reconstitution. The use of V 15-1 thus allows us to prepare a Varicella vaccine with the OKA strain (> 2000 PFU per dose) which has good stability at 5 degrees C. A Varicella vaccine using a live attenuated virus strain OKA was developed in 1974 by Takahashi in Japan [3, 4]. The virus was isolated from vesicular fluid collected from a child with chicken pox. After propagation in human embryonic lung cells (HEC), guinea pigs embryonic cells (GPE) and human diploid cells (WI 38), the virus was attenuated. All the licensed vaccines are prepared with the OKA strain [5].