Innocuity testing of foot-and-mouth disease vaccines. II. Aziridine-inactivated antigen produced in baby hamster kidney cells

Methods for the testing of preparations of aziridine-inactivated foot-and-mouth disease virus for the absence of infective particles were studied. The system used for virus production, suspension cultures of baby hamster kidney cells, proved to be the most sensitive detection system for traces of infective virus as long as the 146S antigen concentration was below 1 microgram per 10(6) cells. Above this level interference may mask the presence of non-inactivated virus. Thus in a 1-1 suspension culture 1 mg of inactivated 146S antigen equivalent to at least 300 doses of vaccine could be tested. The kinetics of inactivation may be studied by the agar-cell suspension plaque assay which is nearly equal in sensitivity to the method described above. Antigen concentrations at which interference occurred were also estimated for this type of assay. Inactivation of polyethylene glycol-concentrated virus showed 'tailing-off' and such virus preparations should not be used in vaccine production. The data are discussed with reference to the recommendations for innocuity testing in the European Pharmacopoeia.     

Recovery of Protective Activity in Rabies Virus Vaccines Concentrated and Purified by Four Different Methods

Rabies vaccines concentrated by ultrafiltration, zinc acetate precipitation, ammonium sulfate precipitation, or aluminum phosphate gel adsorption were compared with respect to recovery of protective activity and purity, as measured by protective activity per mg of protein. Vaccine obtained by ammonium sulfate precipitation had a better recovery rate and a higher purity than those prepared by the other methods. Potent vaccines were also obtained by the zinc acetate precipitation and aluminum phosphate gel adsorption methods, whereas ultrafiltration was the least satisfactory method from the standpoint of vaccine purity. Chromatography of virus concentrated by ultrafiltration on a cellulose ion exchange column reduced the level of nonviral proteins. The protective activity data obtained for the vaccines examined in these experiments were found to correlate with the vaccine's complement fixation titer per mg of protein.     

High-viability lyophilized Bacille Calmette-Guérin vaccine produced by deep-culture technique.

Evidence suggests that Bacille Calmette-Guérin (BCG) vaccine for use in cancer immunotherapy should have the following characteristics: high viability which is maintained on storage; high ratio of live to dead cells; high proportion of single cells; and low content of soluble antigen. The production of a vaccine with these characteristics was accomplished by use of a deep-culture technique. The medium was modified Proskauer and Beck medium containing Tween 80 and glucose. The mass culture was grown in a Wheaton double-side-arm bottle (6 liters of medium in an 8-liter container), aerated by means of an aquarium aerator and mixed by a magnetic stirrer. The culture was incubated 7 to 9 days at 37 degrees C, concentrated 11 to 15 times by ultrafiltration, diluted with equal parts of 25% lactose, and then lyophilized. The lyophilized ampoules, stored at -70 degrees C, were cultured at intervals ranging from 3 days to 450 days, and no loss in viability was observed. The mean number of viable BCG per ml of reconstituted vaccine was 8.75 log10. The viable count was 90% of the total bacterial count. Moreover, 85% of the cells were present as single bacilli.     

High-viability lyophilized Bacille Calmette-Guérin vaccine produced by deep-culture technique.

Evidence suggests that Bacille Calmette-Guérin (BCG) vaccine for use in cancer immunotherapy should have the following characteristics: high viability which is maintained on storage; high ratio of live to dead cells; high proportion of single cells; and low content of soluble antigen. The production of a vaccine with these characteristics was accomplished by use of a deep-culture technique. The medium was modified Proskauer and Beck medium containing Tween 80 and glucose. The mass culture was grown in a Wheaton double-side-arm bottle (6 liters of medium in an 8-liter container), aerated by means of an aquarium aerator and mixed by a magnetic stirrer. The culture was incubated 7 to 9 days at 37 degrees C, concentrated 11 to 15 times by ultrafiltration, diluted with equal parts of 25% lactose, and then lyophilized. The lyophilized ampoules, stored at -70 degrees C, were cultured at intervals ranging from 3 days to 450 days, and no loss in viability was observed. The mean number of viable BCG per ml of reconstituted vaccine was 8.75 log10. The viable count was 90% of the total bacterial count. Moreover, 85% of the cells were present as single bacilli.     

Marek''s disease herpesviruses. IV. Molecular characterization of Marek''s disease herpesvirus A antigen

Marek's disease herpesvirus A antigen (MDHV-A) was identified as a 61,000- to 65,000-dalton glycoprotein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis after immunoprecipitation from the culture medium of both [35S]methionine- and [14C]glucosamine-labeled infected cells by specific rabbit serum directed against MDHV-A. Rigorous identification was accomplished by selective blocking of this specific immunoprecipitation of the glycoprotein with purified MDHV-A that was isolated at its characteristic isoelectric point. These results identify and characterize MDHV-A in terms of the previously determined physical and chemical properties of the antigen. A molecule of similar size was immunoprecipitated from the culture medium of cells infected with herpesvirus of turkeys, extending previous observations about the identity of a potentially important common antigen shared by MDHV and the nonpathogenic vaccine virus, herpesvirus of turkeys.     

Typing foot-and-mouth disease virus by fluorescent antibody technique.

Typing of foot-and-mouth disease (FMD) virus was performed by the direct fluorescent antibody (FA) technique. Type-specific FA was prepared from the following two sorts of procedures: (1) FA against live virus (FA-live) was prepared from hyperimmune serum taken from guinea pigs having received live FMD virus. Then it was adsorbed with concentrated heterotype antigen. (2) FA against inactivated virus (FA-Inact) was prepared from antiserum taken from guinea pigs immunized with purified FMD virus inactivated with acetylethyleneimine. Seventeen strains of FMD virus (seven strains of type A, seven strains of type O, and three strains of thpe C) were used. Type-specific FMD virus antigen was detected distinctly from the monolayer of BHK cells infected with each type of virus and fixed in acetone, in spite of negative results obtained from the cells fixed in methyl alcohol. All the 17 strains were typed successfully by the implementation of these two FA methods.     

Immunofluorescence in the Study of Marek''s Disease: I. Detection of Antigen in Cell Culture and an Antigenic Comparison of Eight Isolates 1

The indirect fluorescent-antibody (FA) test was applied to the detection of Marek's disease (MD) antigen in cell culture and antibody in the serum of birds. For the detection of antigen, sera were obtained from birds hyperimmunized with the JM strain of MD. MD antigen could be detected in the nucleus and in the cytoplasm of duck and chick embryo fibroblasts and in those of chick kidney cells infected with material known to contain the MD virus. Uninoculated cultures of chicken cells were always free of MD antigen. When chick kidney cells were infected with a stock cellular preparation of MD virus, infected cells could be detected after 24 hr with the FA test. At this time no cytopathological areas were seen by conventional light microscopy. By 7 days after infection, the same number of infected areas were detected by both methods, and the fluorescent areas coincided with the cytopathological areas. This indicates that the fluorescent areas and the areas with cytopathology are caused by the same agent. A straight-line relationship between the dilution of inoculum and the number of fluorescent or morphological foci obtained indicates that one infectious unit produced one fluorescent or morphological focus. In addition, this time sequence study confirmed the cell association of the virus and demonstrated the cell-to-cell spread of infection. Cell cultures inoculated with eight different isolates of MD were tested in all combinations with sera prepared against the same isolates. The antigens were indistinguishable from one another, indicating that either the strains are antigenically identical or there is a common antigen or contaminant in all of them so that they stained equally well. The FA test can detect MD antigen before cytopathological areas develop in cell culture; however, the small size of the area usually examined precludes its use in initial isolations in which only a small number of infectious units are present in the inoculum. MD-infected cells contain a heat-stable antigen similar to that found in herpes simplex-infected cells.     

Hemagglutination-Inhibition Method and Immunofluorescence Staining with Venezuelan Equine Encephalomyelitis Virus

Hemagglutination and fluorescent antibody (FA) are compared for the direct detection of virus devoid of host cells. A determination was made of the minimal number of tissue plaque-forming units of Venezuelan equine encephalomyelitis virus that could be detected by the hemagglutination technique. Similar concentrations of the virus in bovine albumin borate saline, Brain Heart Infusion broth (Difco), and demineralized water were tested by the FA technique. Somewhat higher concentrations of the virus in bovine albumin borate saline were used in the hemagglutination-inhibition test. The quantitative hemagglutination procedure employed for these studies was carried out at 37 C for 75 min with variations in concentration of goose red cells. As a result of lowering the red cell concentration, smaller concentrations of virus were detected. The direct FA staining procedure applied to slide preparations containing known numbers of tissue culture plaque-forming units of virus was negative. Adsorbed viral antigen on agglutinated goose erythrocytes was visualized by direct and indirect FA techniques.     

Removal of proteoglycans increases efficiency of retroviral gene transfer

We have previously shown that medium conditioned by virus producer cells inhibits retrovirus transduction, and that a portion of the inhibitory activity is sensitive to chondroitinase ABC. In this study, we have quantitatively evaluated the fraction of the inhibitory activity that is due to chondroitinase ABC-sensitive material and partially characterized the inhibitors. The kinetics of chondroitinase ABC digestion of glycosaminoglycans and virus inhibitory activity in cell culture medium were measured, and the results used to estimate the amount of the chondroitinase ABC-sensitive virus inhibitory activity that was initially in the medium. We found that up to 76% of the inhibitory activity of medium conditioned by packaging cells derived from NIH 3T3 cells is sensitive to chondroitinase ABC. The remainder of the inhibitory activity is not sensitive to other glycosaminoglycan lyases (heparitinase I or heparinase I), which suggests that substances other than glycosaminoglycans or proteoglycans are present in virus stocks and inhibit transduction. To further characterize the inhibitors, proteoglycans from conditioned medium were purified by batch anion exchange and size exclusion chromatography. Two major size groups (100 kDa and 950 kDa) of proteoglycans were isolated. Transduction was inhibited 50% by 0.6 microg/mL of the high-molecular-weight proteoglycan or by 1.7 microg/mL of the low-molecular-weight proteoglycan. Significantly, the proteoglycans, because of their large size and poor sieving properties, coconcentrated with virus particles concentrated by ultrafiltration and prevented any significant increases in transduction efficiency. Transduction efficiencies of virus stocks were increased more than tenfold by ultrafiltration, but only when the concentrated virus was treated with chondroitinase ABC.     

Novel AAV-based genetic vaccines encoding truncated dengue virus envelope proteins elicit humoral immune responses in mice

The envelope protein of dengue virus is involved in host cell attachment for entry and induction of protective immunity. Current efforts are focused on producing a tetravalent vaccine by mixing four monovalent vaccine components. In this work, we developed a genetic vaccine based on a novel adeno-associated viral (AAV) vector expressing the carboxy-terminal truncated envelope protein (79E) of dengue virus. The expression of the recombinant 79E protein in HEK 293 cells was confirmed by Western blot. Vectors packaged with novel AAV capsids (AAV2/8 or AAV2/rh32.33) were injected into C57BL/6 mice intramuscularly. Dengue virus antigen was produced in the mice and induced long-lasting antibody responses against the dengue virus still detectable 20 weeks after immunization. AAV2/8 vaccine induced higher anti-dengue virus antibody levels than AAV2/rh32.33 vaccine or AAV plasmid. Furthermore, the anti-dengue antibodies could neutralize homogeneous dengue virus. These results demonstrated that the AAV vaccines possessed appropriate immunogenicity and could be used for the development of an effective dengue vaccine.     

精制原代地鼠肾细胞狂犬病疫苗制备工艺的研究

通过ａＧ 株病毒在金黄地鼠肾细胞中培养,而制备的一种新型灭活狂犬病精制疫苗已获成功。该纯化方法包括醋酸锌沉淀和Ｓｅｐｈａｒｏｓｅ ４ＦＦ柱层析,所生产的疫苗质量完全达到新型狂犬病疫苗的要求。该工艺方法简单,成本低廉,是一种理想的狂犬病疫苗生产方法。     

Potency of adenovirus vaccines: comparison of unconcentrated, concentrated, and soluble antigen preparations

Five adenoviruses were effectively concentrated and partially purified by methanol precipitation. The soluble antigens from one adenovirus concentrate were obtained by adsorption to and elution from calcium phosphate. Formaldehyde-inactivated vaccines prepared from the virus concentrates were more antigenic in guinea pigs than a National Institutes of Health reference vaccine or one prepared from unconcentrated adenovirus. The soluble antigens also proved to be antigenic. The data indicate that adenovirus vaccines of superior potency can be prepared from concentrated virus preparations and that the extracted soluble antigens are immunogenic.     

Production of inactivated influenza H5N1 vaccines from MDCK cells in serum-free medium

Background

Highly pathogenic influenza viruses pose a constant threat which could lead to a global pandemic. Vaccination remains the principal measure to reduce morbidity and mortality from such pandemics. The availability and surging demand for pandemic vaccines needs to be addressed in the preparedness plans. This study presents an improved high-yield manufacturing process for the inactivated influenza H5N1 vaccines using Madin-Darby canine kidney (MDCK) cells grown in a serum-free (SF) medium microcarrier cell culture system.

Principal Finding

The current study has evaluated the performance of cell adaptation switched from serum-containing (SC) medium to several commercial SF media. The selected SF medium was further evaluated in various bioreactor culture systems for process scale-up evaluation. No significant difference was found in the cell growth in different sizes of bioreactors studied. In the 7.5 L bioreactor runs, the cell concentration reached to 2.3×10⁶ cells/mL after 5 days. The maximum virus titers of 1024 Hemagglutinin (HA) units/50 µL and 7.1±0.3×10⁸ pfu/mL were obtained after 3 days infection. The concentration of HA antigen as determined by SRID was found to be 14.1 µg/mL which was higher than those obtained from the SC medium. A mouse immunogenicity study showed that the formalin-inactivated purified SF vaccine candidate formulated with alum adjuvant could induce protective level of virus neutralization titers similar to those obtained from the SC medium. In addition, the H5N1 viruses produced from either SC or SF media showed the same antigenic reactivity with the NIBRG14 standard antisera.

Conclusions

The advantages of this SF cell-based manufacturing process could reduce the animal serum contamination, the cost and lot-to-lot variation of SC medium production. This study provides useful information to manufacturers that are planning to use SF medium for cell-based influenza vaccine production.     

HAV病毒液的3种浓缩方法比较

目的:对HAV病毒液的3种常见浓缩方法进行分析比较,为HAV病毒研究及规模化疫苗生产提供参考。方法:使用MILLIPORE PELLICON超滤、PEG 6000沉淀、蔗糖-甘油垫三种方法对纯化HAV病毒液进行浓缩,用ELISA方法对浓缩液进行抗原滴度检测,计算不同浓缩方法的回收率。结果:HAV病毒液经过7次超滤循环浓缩,平均回收率为86%;PEG浓缩方法回收率平均72.5%;蔗糖-甘油离心浓缩方法平均回收率53.3%。结论:蔗糖/甘油超离心法,集纯化浓缩一体,适用于样品量较少,需要高浓度样品的试验;PEG浓缩得率适中,操作简单,应用范围较广;超滤膜浓缩在大规模疫苗生产或样品量较大时适用,但需控制样品浓度及浓缩倍数不能太高,以免样品损失。     

HAV病毒液的3种浓缩方法比较

目的：对HAV病毒液的3种常见浓缩方法进行分析比较,为HAV病毒研究及规模化疫苗生产提供参考。方法：使用MILLIPOREPELLICON超滤、PEG6000沉淀、蔗糖．甘油垫三种方法对纯化HAV病毒液进行浓缩,用ELISA方法对浓缩液进行抗原滴度检测,计算不同浓缩方法的回收率。结果：HAV病毒液经过7次超滤循环浓缩,平均回收率为86％;PEG浓缩方法回收率平均72．5％;蔗糖．甘油离心浓缩方法平均回收率53．3％。结论：蔗糖／甘油超离心法,集纯化浓缩一体,适用于样品量较少,需要高浓度样品的试验;PEG浓缩得率适中,操作简单,应用范围较广;超滤膜浓缩在大规模疫苗生产或样品量较大时适用,但需控制样品浓度及浓缩倍数不能太高。以免样品损失。     

Identification of protective T-cell antigens for smallpox vaccines

Background aimsE3L is an immediate-early protein of vaccinia virus (VV) that is detected within 0.5 h of infection, potentially before the many immune evasion genes of vaccinia can exert their protective effects. E3L is highly conserved among orthopoxviruses and hence could provide important protective T-cell epitopes that should be retained in any subunit or attenuated vaccine. We have therefore evaluated the immunogenicity of E3L in healthy VV-vaccinated donors.MethodsPeripheral blood mononuclear cells from healthy volunteers (n = 13) who had previously received a smallpox vaccine (Dryvax) were activated and expanded using overlapping E3L peptides and their function, specificity and antiviral activity was analyzed. E3L-specific T cells were expanded from 7 of 12 (58.3%) vaccinated healthy donors. Twenty-five percent of these produced CD8+ T-cell responses and 87.5% produced CD4+ T cells. We identified epitopes restricted by HLA-B35 and HLA-DR15.ResultsE3L-specific T cells killed peptide-loaded target cells as well as vaccinia-infected cells, but only CD8+ T cells could prevent the spread of infectious virus in virus inhibition assays. The epitopes recognized by E3L-specific T cells were shared with monkeypox, and although there was a single amino acid change in the variola epitope homolog, it was recognized by vaccinia-specific T-cells.ConclusionsIt might be important to include E3L in any deletion mutant or subunit vaccine and E3L could provide a useful antigen to monitor protective immunity in humans.     

A partial characterization of a Sertoli cell-secreted protein stimulating Leydig cell testosterone production.

To examine whether immature rat Sertoli cells in culture secrete a factor(s) which stimulates testosterone production by mature mouse Leydig cells, Sertoli cell-enriched cultures were prepared from 3-week-old male rats with trypsin and collagenase. Sertoli cells were plated at an initial density of 3-5 x 10(6) cells/35 mm well and cultured in 3 ml serum free media supplemented with insulin (10 micrograms/ml). Sertoli cell culture medium (SCCM) collected every 3rd day was added to Leydig cells (10(6) cells in 1 ml of MEM with 2% steroid-free FCS) prepared from 10-week-old mice by mechanical separation and incubated for 3 h at 34 degrees C. Secreted testosterone was determined by RIA. SCCM 15 times concentrated by Amicon YM10 membrane demonstrated a dose-dependent stimulation of testosterone production, whereas there was no effect on testosterone secretion when Leydig cells were maximally stimulated by LH. Leydig cell stimulating activity was retained by both a dialysis membrane with a pore size of 24 A and an ultrafiltration membrane with a molecular weight cut-off of 10 kDa. However, activity was reduced by heating at 60 degrees C for 30 min and almost lost after incubation with 0.1% trypsin for 1 h at 37 degrees C. This activity was not retained by means of a Con A-Agarose column and was demonstrated only in break-through fractions. HPLC gel filtration of a 15 times concentrated SCCM preparation on a TSK gel G3000SW revealed Leydig cell-stimulating activity at approximately 13 kDa.(ABSTRACT TRUNCATED AT 250 WORDS)     

Harvesting and concentration of human influenza A virus produced in serum-free mammalian cell culture for the production of vaccines

A process scheme for the harvesting and concentration of cell culture-derived human influenza A virus is presented. The scheme comprises two static filtration steps, chemical inactivation by beta-propiolactone and cross-flow ultrafiltration. Human influenza A virus A/PR/8/34 (H1N1) was produced in roller bottles with serum-free medium using MDCK cells as a host. Cultivations resulted in specific hemagglutination (HA) activities of 393 HAU (100 microL)(-1) and turbidities of 0.479 OD measured as the extinction of light at 700 nm (mean values are presented). The concentrations of soluble protein and DNA in the harvests were 72 microg/mL and 5.73 microg/mL, respectively. An average product yield of 79% based on HA activity was achieved after clarification by depth (85%) and microfiltration (93%). The turbidities of cell culture supernatants were reduced to 2% of their initial value. Concentration with 750 kDa hollow-fiber modules by a factor of 20 resulted in 97% recovery of the product when operated at a constant flux of 28 L/(m(2) h) and a wall shear rate of 9,500 s(-1). The amount of protein and DNA could be reduced to 16% and 33% of their initial amount, respectively. An overall product yield of 77% was achieved. Clarified supernatants and concentrates were further analyzed by non-reducing SDS-PAGE and agarose gel electrophoresis. Particle volume distributions of concentrates were obtained by dynamic light scattering analysis. From the results it can be concluded that the suggested process scheme is well suited for the harvesting and concentration of cell culture-derived influenza A virus.     

Quantitation of poliovirus antigens in inactivated viral vaccines by enzyme-linked immunosorbent assay using animal sera and monoclonal antibodies

Recent advances in methods for the manufacture of inactivated poliovirus vaccines have resulted in increased vaccine immunogenicity. In conjunction with this capability it is important to have available highly sensitive and quantitative potency assays. The potential suitability of enzyme-linked immunoassay (ELISA) was evaluated using animal sera with neutralizing antibodies or neutralizing monoclonal antibodies for antigen detection in potency tests. The monoclonal antibodies developed, which bound D antigen but not C antigen, were neutralizing unless relatively weakly reactive. Those that bound C antigen only were non-neutralizing. Those that bound both C and D antigens were sometimes neutralizing. D-specific and D/C-specific neutralizing monoclonal antibodies against type-2 poliovirus protected mice on passive immunization against paralytic disease and death from the MEF strain virus. Potency measurements by ELISA using either D-specific neutralizing monoclonal antibodies or type-specific goat sera for antigen detection were sensitive and precise. Tests using C-specific monoclonal antibodies for antigen detection indicated that increased C antigen content may result in falsely elevated reactivities of animal sera with some vaccines. Monoclonal antibodies may be useful ELISA reagents for IPV potency testing.     

Live oral poliovirus vaccines and simian cytomegalovirus.

Live oral poliovirus vaccines (OPV) are often produced in primary Cercopithecus monkey kidney (CMK) cells. The kidneys of these monkeys are often latently infected with simian cytomegalovirus (SCMV), and CMK cultures are frequently contaminated with SCMV. We tested human, monkey and rabbit tissue culture systems, and found that MRC-5 cells are most sensitive for detection of SCMV. To address the question of whether OPV could be contaminated with infectious SCMV, we inoculated MRC-5 cells with neutralized OPV manufactured in the United States between 1972 and 1998. Infectious SCMV was not found in any of the vaccine lots tested. We also used the polymerase chain reaction (PCR) to search for SCMV DNA in live oral poliovirus vaccines; SCMV DNA sequences were found in several of the vaccine lots manufactured prior to 1992.