Comparative study of the smallpox vaccines from B-51, EM-63 and L-IVP in a controlled epidemiological experiment. II. The characteristiics of the immunogenicity of the smallpox vaccines]

Immunogenicity of smallpox vaccines prepared of EM-63, L-IVP, and B-51 strains was studied under conditions of strict controlled epidemiological trial. Skin reactions to revaccination and vaccines antigenic activity indices were detemined in the persons vaccinated. Changes in the virus-neutralizing and antibodies suppressing hemagglutination was the same in persons vaccinated with any of the preparations tested. The maximal virus-neutralizing antibodies level was determined 1 month after the vaccination and persisted without any essential changes for one year. The titre of hemagglutination inhibiting antibodies also reached the maximum in one month, but diminished gradually by the end of one year after the vaccination. There were found no significant differences in the antigenic activity of the vaccines. The vaccines studied also displayed no difference in the number and character of skin reactions to revaccination. In comparing the antibodies level and the character of skin reactions to revaccination it was found that the titres of hemagglutination inhibiting antibodies and virus-neutralizing antibodies of 1:40 and over were in the great majority of cases determined in the blood sera of the vaccinated persons with the immediate and negative reactions to revaccination, i. e. in those with intensive postvaccinal immunity.     

布氏杆菌病疫苗的应用和研究现状

布氏杆菌病是由布氏杆菌引起的一种重要的人兽共患病。布氏杆菌具有宿主广泛、传染性强以及感染后根治困难等特点,对畜牧业和人类健康均构成严重威胁,疫苗免疫是预防和控制布氏杆菌病的主要措施。迄今国内外已有多个弱毒活疫苗在使用,但均存在一定的缺陷,因此研究更理想的疫苗一直是控制布氏杆菌病的重点。目前除了常规诱变筛选新的弱毒株外,人们正通过基因工程技术构建重组弱毒疫苗、DNA疫苗以及亚单位疫苗。本文简述了布氏杆菌病疫苗的应用及新型疫苗的研究现状。     

A mouse-based assay for the pre-clinical neurovirulence assessment of vaccinia virus-based smallpox vaccines

Post-vaccinal encephalitis, although relatively uncommon, is a known adverse event associated with many live, attenuated smallpox vaccines. Although smallpox vaccination ceased globally in 1980, vaccine manufacture has resumed in response to concerns over the possible use of smallpox virus as an agent of bioterrorism. To better support the production of safer smallpox vaccines, we previously reported the development of a mouse model in which a relatively attenuated vaccine strain (Dryvax^®) could be discerned from a more virulent laboratory strain (WR). Here we have further tested the performance of this assay by evaluating the neurovirulence of several vaccinia virus-based smallpox vaccines spanning a known range in neurovirulence for humans. Our data indicate that testing of 10–100 pfu of virus in mice following intracranial inoculation reliably assesses the virus's neurovirulence potential for humans.     

Characterization of NADP-dependent 7 beta-hydroxysteroid dehydrogenases from Peptostreptococcus productus and Eubacterium aerofaciens.

Peptostreptococcus productus strain b-52 (a human fecal isolate) and Eubacterium aerofaciens ATCC 25986 were found to contain NADP-dependent 7 beta-hydroxysteriod dehydrogenase activity. The enzyme was synthesized constitutively by both organisms, and the enzyme yields were suppressed by the addition of 0.5 mM 7 beta-hydroxy bile acid to the growth medium. Purification of the enzyme by chromatography resulted in preparations with 3.5 (P. productus b-52, on Sephadex G-200) and 1.8 (E. aerofaciens, on Bio-Gel A-1.5 M) times the activity of the crude cell extracts. A pH optimum of 9.8 and a molecular weight of approximately 53,000 were shown for the enzyme of strain b-52, and an optimum pH at 10.5 and a molecular weight of 45,000 was shown for that from strain ATCC 25986. Kinetic studies revealed that both enzyme preparations oxidized the 7 beta-hydroxy group in unconjugated and conjugated bile acids, a lower Km value being demonstrated with free bile acid than with glycine and taurine conjugates. No measureable activity against 3 alpha-, 7 alpha-, or 12 alpha-hydroxy groups was detected in either enzyme preparation. When tested with strain ATCC 25986, little 7 beta-hydroxy-steroid dehydrogenase activity was detected in cells grown in the presence of glucose in excess. The enzyme from strain b-52 was found to be heat labile (90% inactivation at 50 degrees C for 3 min) and highly sensitive to sulfhydryl inhibitors.     

The efficacy of killed Trypanosoma evansi vaccines in mice.

Four strains of Trypanosoma evarsi (D3, D4, D5 and D6) isolated from German shepherd dogs were inoculated into mice, and infected blood was used to prepare 9 separate killed vaccines. White mice inoculated with 1:100 diluted PBS vaccine, 0.5% carbol vaccine, or 100% Lugol vaccine showed survival rates of more than 60%. Among these 3 vaccines PBS vaccine and 0.5% carbol vaccine showed higher survival rates at 1:500 and 1:1000 dilutions, respectively. When young mice (15-20 g) were immunized with PBS vaccine, they resisted challenge with homologous strains, D3 strain in single injection, D6 strain in double injections and all strains in 5 injections. Protection however was not observed in old mice (25-30 g) give the same vaccine preparation. When mice were vaccinated with a single injection of D3 vaccine and challenged with heterologous strains, only those challenged with D4 strain at 10-5 dilution showed a survival rate of more than 60%. There was no difference in protective ability among PBS vaccine, agar adjuvant and kaolin adjuvant vaccines. Agglutinating antibody was demonstrated in mice receiving 5 injections of PBS vaccine.     

Results of a study of new preparations of inactivated whole-virion influenza vaccines for the protection of children in the USSR

The safety, reactogenic properties and antigenic potency of inactivated whole-virion influenza vaccines produced in the USSR were studied on 1,117 schoolchildren in limited coded clinico-immunological observations. Inactivated chromatographic influenza vaccine obtained from strain A/Texas/1/77 (H3N2) and a variant of this vaccine, developed specially for children and obtained from strains A/Texas/1/77 and B/Leningrad/76, were used for immunization. Both preparations were introduced intradermally in a single injection in a volume of 0.1-0.2 ml by means of bi-3 jet injector. The content of hemagglutinin in this volume varied from 3.0 to 8.0 micrograms. Clinico-laboratory investigations demonstrated the safety of mono- and bivalent inactivated whole-virion influenza vaccine administered intradermally in a single injection to children of school age. The vaccines showed low reactogenicity and high antigenic potency in children aged 7-10 and 11-14 years, and the optimal doses of the preparations were selected for children of different age groups. The distinct prophylactic effectiveness of inactivated chemical chromatographic influenza vaccines in children aged 11-14 years was revealed 11 months after immunization, the index of immunological effectiveness being 1.7.     

Experimental research on cholera vaccines. Local immunity

Parenteral immunization of rabbits with cholera vaccine decreased the number of Vibrio cholerae adhering to the mucous membrane of the small intestine. Cholera toxoid and the complex preparation ensure protection from the local action of cholera toxin on the ligated loop of the rabbit intestine, while cholera vaccine produces no effect under the same conditions. The use of three preparations under study leads to the decrease of exudative reaction to the introduction of live V. cholerae, the effectiveness of these vaccines growing in the following order: cholera vaccine, cholera toxoid, the complex preparation.     

Antigenic, immunologic and genetic characterization of rough strains B. abortus RB51, B. melitensis B115 and B. melitensis B18

The lipopolysaccharide (LPS) is considered the major virulent factor in Brucella spp. Several genes have been identified involved in the synthesis of the three LPS components: lipid A, core and O-PS. Usually, Brucella strains devoid of O-PS (rough mutants) are less virulent than the wild type and do not induce undesirable interfering antibodies. Such of them proved to be protective against brucellosis in mice. Because of these favorable features, rough strains have been considered potential brucellosis vaccines. In this study, we evaluated the antigenic, immunologic and genetic characteristics of rough strains B. abortus RB51, B. melitensis B115 and B. melitensis B18. RB51 derived from B. abortus 2308 virulent strain and B115 is a natural rough strain in which the O-PS is present in the cytoplasm. B18 is a rough rifampin-resistan mutant isolated in our laboratory. The surface antigenicity of RB51, B115 and B18 was evaluated by testing their ability to bind antibodies induced by rough or smooth Brucella strains. The antibody response induced by each strain was evaluated in rabbits. Twenty-one genes, involved in the LPS-synthesis, were sequenced and compared with the B. melitensis 16M strain. The results indicated that RB51, B115 and B18 have differences in antigenicity, immunologic and genetic properties. Particularly, in B115 a nonsense mutation was detected in wzm gene, which could explain the intracellular localization of O-PS in this strain. Complementation studies to evaluate the precise role of each mutation in affecting Brucella morphology and its virulence, could provide useful information for the assessment of new, attenuated vaccines for brucellosis.     

The action of pertussis vaccines and GMDP on the change in the enzymatic activity of macrophages from peritoneal exudate

The influence of whole-cell and acellular pertussis vaccines, introduced both alone and in combination with N-acetylglucosaminylmuramyl-2-alanine-D-isoglutamine (GMDP) on the activity of two enzymes of peritoneal exudate macrophages (5'-nucleotidase and Na+K(+)-adenosine triphosphatase) was studied. The study revealed that both pertussis vaccines exhibited immunomodulating properties, these properties being most pronounced in whole-cell pertussis vaccine. The use of GMDP in combination with pertussis vaccines led to changes in the enzymatic activity of peritoneal exudate macrophages, which was indicative of a decrease in the immunomodulating action of pertussis preparations.     

Insights into human CD8(+) T-cell memory using the yellow fever and smallpox vaccines

Live virus vaccines provide a unique opportunity to study human CD8(+) T-cell memory in the context of a controlled, primary acute viral infection. Yellow fever virus-17D and Dryvax are two such live-virus vaccines that are highly efficacious, used worldwide and provide long-term immunity against yellow fever and smallpox respectively. In this review, we describe the properties of virus-specific memory CD8(+) T cells generated in smallpox and yellow fever vaccinees. We address fundamental questions regarding magnitude, functional quality and longevity of the CD8(+) T-cell response, which are otherwise challenging to address in humans. These findings provide insights into the attributes of the human immune system as well as provide a benchmark for the optimal quality of a CD8(+) T-cell response that can be used to evaluate novel candidate vaccines.     

Detoxified bacterial endotoxins. I. Preparation and biological properties of an acetylated crude endotoxin from Salmonella typhimurium

Martin, William J. (University of Utah, Salt Lake City), and Stanley Marcus. Detoxified bacterial endotoxins. I. Preparation and biological properties of an acetylated crude endotoxin from Salmonella typhimurium. J. Bacteriol. 91:1453-1459. 1966.-Acetylation of a crude endotoxin prepared by the Roschka-Edwards (RE) procedure from a strain of Salmonella typhimurium yields a product with reduced pyrogenicity in rabbits as well as one which is nontoxic in mice. A reduction in pyrogenicity of approximately 100 times was noted with this acetylated crude endotoxin when compared with the parent RE preparation. A comparison was made of immunogenicity with mice of Boivin, RE, and acetylated Roschka-Edwards (Acet-RE) preparations with a heat-killed, phenol-preserved (HP) vaccine prepared from the same strain of S. typhimurium. Less than pyrogenic doses of all vaccines were not protective. The least pyrogenic preparation (Acet-RE) was immunogenically effective in about five times the minimal pyrogenic dose. The data suggest that the Acet-RE preparation should be considered further in the search for enteric fever vaccines with lowered potential for undesirable systemic responses.     

Evaluation of the potential use of inactivated influenza centrifuged vaccines with various hemagglutinin levels for immunizing schoolchildren

The safety, reactogenic properties and immunogenic potency of inactivated influenza centrifuged vaccines with different hemagglutinin content were studied in observations on children aged 11-15 and 7-10 years. According to the results of clinico-laboratory investigations, commercial influenza vaccine and its variant with hemagglutinin content reduced by half were found to be safe and showed faintly pronounced reactogenic properties in children. After vaccination hyperemia developed at the site of injection, moderate in 5% of the vaccinees aged 7-10 years and mild in other vaccinees of both age groups. The immunogenic potency of the preparations was determined by the specific features of influenza virus strains: strain A (H1N1) induced seroconversion in 62-94% and strain A (H3N2), in 67-96% of children.     

Expert examination of the immunogenic activity and toxicity of the pertussis component of adsorbed and non-adsorbed diphtheria-tetanus-pertussis vaccines. Results of interlaboratory investigations under the WHO project "Reactogenicity and Toxicity of DPT Vaccines"

Since the DPT vaccine is broadly used for the prevention of diphtheria, tetanus and pertussis' its preparations should meet special quality requirements. The present study was aimed at evaluating the reproducibility of laboratory methods utilized to assess the protective activity and toxicity of the pertussis component as well as at examining the feasibility of expert estimations of product quality to enhance the validity of findings. The results of interlaboratory comparative examination of quality parameters of the tested preparations revealed that the routine laboratory quality control methods were not sufficiently standardized as their application in different laboratories did not always produce identical results. The WHO criteria to evaluate the toxicity of pertussis vaccines are far from perfect since vaccines with pronounced toxicity can only be distinguished from those with moderate to mild toxicity after the administration to tested mice of vaccines at a single infant dose of 0.5 ml. To enhance the reproducibility of methods employed in the laboratory, appropriate standard specimens of the preparation should be used serving as a measure of different quality parameters; all test conditions should be also standardized as far as possible. To enable objective quality evaluation of medical biological preparations, the degree of experiment reproducibility should be regularly verified in interlaboratory tests on an international scale as well as inside those countries which have several manufacturers of a given preparation. It appears expedient to set up an international system of expert evaluation of quality of biological preparations by appointing several regional and national centres which meet the requirements for expert laboratories.     

Evaluation of the vaccinal process in skin-scarification and oral immunization of rabbits with live smallpox vaccines

On the basis of comparative experimental evaluation of specific features in the course of the vaccinal process after the immunization of laboratory animals with live smallpox vaccines, intended for oral use (in tablets) and for skin scarification was proposed. In experiments on rabbits, made with the use of virological and immunological methods, the counteraction of the elements constituting the vaccinal process was analyzed, the integral evaluation of its course was given, the greater safety of the oral preparation in comparison with the traditional vaccine for immunization by skin-scarification method were established. The conclusion was made that oral immunization was the safest immunization method under modern conditions and promising one for using live vaccines with population immunity being at a low level or absent.     

Immunogenicity and tumor protective activity of B16 melanoma vaccines

The immunogenicity and tumor-protective activity of different vaccines were examined and compared with murine B16 melanoma. All vaccines were prepared from material shed into culture medium by B16 melanoma cells. Vaccine I was generated by concentrating the shed material. Vaccine II was partially purified by precipitating the shed material with 50% ammonium sulfate followed by sephadex G-200 column chromatography. Vaccine III was concentrated shed material that was treated with 0.5% NP-40 and then ultracentrifuged to remove transplantation antigens. Mice were immunized to equal protein concentrations of vaccines weekly for 5 weeks or to control buffer. Antibody, cellular, and tumor-protective immunity to melanoma was measured in all mice 2 weeks following the last immunization. All three vaccine preparations were immunogenic. Vaccine preparation I appeared to be the most immunogenic and the one that most consistently augmented tumor-protective immunity. Augmentation in tumor-protective immunity correlated better with increase in cellular than in humoral immunity to melanoma.     

Evaluation of the reactogenic and immunogenic properties of meningococcal vaccines

The results of the study of the reactogenic and immunogenic properties of meningococcal polysaccharide A + C vaccine in the controlled epidemiological trial, with regard to variations depending on the initial immunological characteristics of vaccinees in terms of the levels of antibodies to the polysaccharides contained in the vaccine, are presented. The study was made on school children: 303 of them were immunized with the meningococcal vaccine under test, and 229 (controls) with adsorbed diphtheria-tetanus toxoid. This study revealed that the reactogenic properties of the preparation were more pronounced in those children whose blood sera had been found to contain no antibodies to polysaccharides A and C prior to immunization. The immunological properties were more pronounced with respect to polysaccharide A. The titer of antibodies to polysaccharide A was found to depend on the previous immunological status of the child, which was indicative of the booster effect produced by the vaccine. The data obtained in the study suggest that the evaluation of the reactogenic and immunogenic properties of newly developed prophylactic preparations should be made with due regard for the previous immunological status of vaccinees in respect to the antigens contained in the meningococcal vaccine under test.     

Evaluation of the neurovirulence test for mumps vaccines.

Neurovirulence tests in Macaca fascicularis using commercial preparations of different vaccine bulks and a wild-type strain revealed that the test was unable to distinguish mixed from pure populations or a suitable vaccine from a related strain which has been shown to be associated with clinical meningitis. However, the test was able to distinguish a wild-type strain from the vaccine strains successfully. The ability of the test to discriminate between acceptable and unacceptable seeds requires further examination.     

The immunogenicity of mono- and associated vaccines made from strains of opportunistic bacteria]

In experiments on white mice the immunogenic potency of two variants of combined vaccines prepared from strains of opportunistic bacteria was compared with that of monovaccines used as the components of the combined vaccines. All the vaccines under study were found highly immunogenic. Decrease of monovaccine share in the combined vaccine did not reduce the immunogenic potency to any of the strains. An 8- to 16-fold increase in the level of specific antibodies in the colostric lactosera of cows immunized with combined vaccines was observed, and the survival rate of newborn calves increased 3- to 4-fold.     

Induction of interferon in man by vaccines.

The purpose of this study was to extend the spectrum of vaccines with interferon-inducing potential in man. The vaccines selected for study were the commercially available attenuated poliomyelitis vaccine type 2 (Sabin strain) and the new live attenuated influenza A/England/42/72 (H3N2) vaccine ("Alice" strain). Five subjects, two of whom had low or undetectable polio type 2 neutralizing antibody levels were given the type 2 vaccine (10-4.7 TCID50) in the standard manner orally. Even though the two individuals with low titers experienced a fourfold or greater antibody rise and one of them shed the virus in his stool, neither they nor the remaining three volunteers developed detectable levels of interferon in their sera obtained at very closely spaced intervals from day 0 to day 25 following immunization. Fifteen subjects were given approximately 10-7.5 TCID50 of influenza A/England/42/72 (H3N2) by nasal drops. Specimens consisting of sera and nasal washings were obtained at closely timed intervals for 23 days, starting with day 3 following immunization. Interferon could be detected in three of nine (33.3%) subjects who had fourfold or greater HI antibody rises. No interferon was detected in nasal washings, however. It is concluded that poliomyelitis is not a good interferon inducers in man. Live attenuated influenza vaccine does induce an interferon response in subjects with low initial serum antibody titers. This response is at best modest. The latter finding also suggests that the attenuation of the Alice strain of influenza A vaccine is not dependent on its interferon inducing potential.     

Detoxified bacterial endotoxns. II. Preparation and biological properties of chemically modified crude endotoxins from Salmonella typhimurium

Martin, William J. (University of Utah, Salt Lake City), and Stanley Marcus. Detoxified bacterial endotoxins. II. Preparation and biological properties of chemically modified crude endotoxins from Salmonella typhimurium. J. Bacteriol. 91:1750-1758. 1966.-Chemical modification of a crude endotoxin prepared by the Roschka-Edwards (RE) procedure from a strain of Salmonella typhimurium yielded products which were nontoxic for mice and had reduced fever effects in rabbits. A reduction in rabbit pyrogenicity of approximately 100 times was noted with a potassium periodate-treated RE preparation when compared with the parent RE preparation. Measured in a similar fashion, pyrogenicity of a potassium methylate-treated RE preparation was reduced by a factor of 10 while pyrogenicity of a boron trifluoride RE preparation was unchanged. All of these endotoxoids, including the parent RE preparation, showed little toxicity for mice. Immunogenicity was determined in mice by comparing Boivin, RE, and endotoxoid preparations with a heat-killed, phenol-preserved (HP) vaccine prepared from the same strain of S. typhimurium. Employing a 10 ld(50) challenge, the protective immunogenicity of the respective vaccines was determined by active immunized mouse protection tests. Although two 100 mug immunizing doses of the Boivin, RE, and the respective endotoxoid preparations varied in mouse protection (potassium methylate RE > Boivin > RE > boron trifluoride RE > potassium periodate RE), it was evident that, with the exception of the potassium methylate preparation, the HP vaccine yielded greatest protection against the 10 ld(50) challenge with S. typhimurium. Further mouse protection experiments suggested that the minimal immunogenic dose of the potassium methylate RE vaccine preparation was approximately 50 mug. These data indicated an approximate fivefold difference between the minimal pyrogenic dose (10 mug) and the minimal immunogenic dose (50 mug). These findings further suggest that potassium methylate RE vaccine preparations should be considered in the search for less toxic enteric fever vaccines.