Ribosomal dysentery vaccine. II. Biological trials of active protection for guinea pigs and mice]

Ribosomal vaccine from Sh. sonnei injected subcutaneously once or twice in physiological saline or in Freund's complete adjuvant produces a marked protective effect against experimental keratoconjunctivitis in guinea pigs. Inhibition of the protective effect by high doses (above 100 microgram) of ribosomal vaccine is evident after a single, but not repeated injections. Protective effect in mice is achieved by immunization with very low doses of ribosomal vaccine: ED50 is 1.2 ng after challenge with 5.6 LD50. The nature of immunogenic factor responsible for the biological activity of the ribosome vaccine is still obscure. In contrast to Boivin's antigen, ribosomal preparations, even in high doses (1000--2000 microgram), have no toxic effect on mice and guinea pigs.     

Live attenuated herpes simplex virus 2 glycoprotein E deletion mutant as a vaccine candidate defective in neuronal spread

A herpes simplex virus 2 (HSV-2) glycoprotein E deletion mutant (gE2-del virus) was evaluated as a replication-competent, attenuated live virus vaccine candidate. The gE2-del virus is defective in epithelial cell-to-axon spread and in anterograde transport from the neuron cell body to the axon terminus. In BALB/c and SCID mice, the gE2-del virus caused no death or disease after vaginal, intravascular, or intramuscular inoculation and was 5 orders of magnitude less virulent than wild-type virus when inoculated directly into the brain. No infectious gE2-del virus was recovered from dorsal root ganglia (DRG) after multiple routes of inoculation; however, gE2-del DNA was detected by PCR in lumbosacral DRG at a low copy number in some mice. Importantly, no recurrent vaginal shedding of gE2-del DNA was detected in immunized guinea pigs. Intramuscular immunization outperformed subcutaneous immunization in all parameters evaluated, although individual differences were not significant, and two intramuscular immunizations were more protective than one. Immunized animals had reduced vaginal disease, vaginal titers, DRG infection, recurrent genital lesions, and recurrent vaginal shedding of HSV-2 DNA; however, protection was incomplete. A combined modality immunization using live virus and HSV-2 glycoprotein C and D subunit antigens in guinea pigs did not totally eliminate recurrent lesions or recurrent vaginal shedding of HSV-2 DNA. The gE2-del virus used as an immunotherapeutic vaccine in previously HSV-2-infected guinea pigs greatly reduced the frequency of recurrent genital lesions. Therefore, the gE2-del virus is safe, other than when injected at high titer into the brain, and is efficacious as a prophylactic and immunotherapeutic vaccine.     

Efficacy of a Parainfluenza Virus 5 (PIV5)-Based H7N9 Vaccine in Mice and Guinea Pigs: Antibody Titer towards HA Was Not a Good Indicator for Protection

H7N9 has caused fatal infections in humans. A safe and effective vaccine is the best way to prevent large-scale outbreaks in the human population. Parainfluenza virus 5 (PIV5), an avirulent paramyxovirus, is a promising vaccine vector. In this work, we generated a recombinant PIV5 expressing the HA gene of H7N9 (PIV5-H7) and tested its efficacy against infection with influenza virus A/Anhui/1/2013 (H7N9) in mice and guinea pigs. PIV5-H7 protected the mice against lethal H7N9 challenge. Interestingly, the protection did not require antibody since PIV5-H7 protected JhD mice that do not produce antibody against lethal H7N9 challenge. Furthermore, transfer of anti-H7 serum did not protect mice against H7N9 challenge. PIV5-H7 generated high HAI titers in guinea pigs, however it did not protect against H7N9 infection or transmission. Intriguingly, immunization of guinea pigs with PIV5-H7 and PIV5 expressing NP of influenza A virus H5N1 (PIV5-NP) conferred protection against H7N9 infection and transmission. Thus, we have obtained a H7N9 vaccine that protected both mice and guinea pigs against lethal H7N9 challenge and infection respectively.     

Immune response of various animals to Akabane disease live virus vaccine

When various animals and routes of inoculation were examined for antibody response to Akabane disease live virus vaccine, the intracerebral (ic) inoculation of mice induced a better antibody response than the subcutaneous (sc) inoculation of calves, guinea pigs, hamsters, mice, or rats. Immunogenicity was compared among lots of this vaccine by performing ic inoculation of mice and sc inoculation of calves and guinea pigs. As a result, there was no distinct significant difference between any two lots of the vaccine, regardless of the animal species used. There was a tendency that the larger the dose of inoculation of the virus, the earlier the production of neutralizing (NT) antibody took place in calves inoculated with the vaccine, and the higher the antibody titer and the rate of taking a turn for positivity for antibody became in these calves. When calves immunized with the vaccine and cows in the field possessing NT antibody were given booster inoculation with the vaccine, the antibody titer showed a significant increase in almost all the calves and cows that exhibited an NT antibody titer of 4 or less at the time of booster inoculation. There were, however, no changes in antibody titer in such calves and cows as presenting an NT antibody titer of 8 or more. Calves and pregnant cows immunized with the vaccine were prevented from viremia and fetal infection when challenged by inoculation with virulent virus.     

Correlation of Clostridium botulinum type C antitoxin titers in mink and guinea pigs to protection against type C intoxication in mink

In USA, the potency of commercial vaccines containing Clostridium botulinum type C toxoid is determined by a mink vaccination-challenge assay outlined in the Code of Federal Regulations, Title 9, Part 113.110. A more humane potency test is desired, and this study provides preliminary data in support of a serological assay that correlates post-vaccination antitoxin titers of guinea pigs to vaccine efficacy in mink. Mink and guinea pigs were injected with varying dilutions of a vaccine containing C. botulinum type C toxoid. Blood samples were collected from each animal prior to challenging the mink with type C toxin. Serum antitoxin titers of mink and guinea pigs were measured by a mouse protection test, and the results were compared to the outcome of the toxin challenge in mink. A dose-dependent antitoxin response was observed in guinea pigs vaccinated with the critical dilutions of vaccine bracketing the minimum protective dose in mink. These preliminary data suggest that it may be possible to correlate post-vaccination antitoxin titers in guinea pigs to vaccine efficacy in mink. This correlation could be used as the basis for a more humane potency test for C. botulinum type C toxoids.     

Immunogenicity of Plague Vaccines in Mice and Guinea Pigs

The median effective doses (ED₅₀) of 28 lots of killed Pasteurella pestis strain 195/P vaccine were determined in mice and guinea pigs. Mice were injected with vaccine alone, whereas guinea pigs received vaccine suspended in incomplete Freund's adjuvant. Potency ratios of vaccines were obtained by comparing the ED₅₀ of the test with that of a reference vaccine. Mean potency ratios of 1.82 ± 0.50 in mice and 3.22 ± 0.56 in guinea pigs were obtained, and the difference between these means was significant, P = <0.01. The number of organisms in the challenge dose did not significantly affect the ED₅₀ of a vaccine in guinea pigs. However, irrespective of vaccinating route, nearly 1,000 times as much vaccine was required in the absence of adjuvant as in its presence to produce comparable protective indexes in the guinea pig. The response of guinea pigs did not offer any improvement over mice in evaluating the efficacy of plague vaccines.     

Immunogenicity,Protective Efficacy,and Non-Replicative Status of the HSV-2 Vaccine Candidate HSV529 in Mice and Guinea Pigs

HSV-2 vaccine is needed to prevent genital disease, latent infection, and virus transmission. A replication-deficient mutant virus (dl5-29) has demonstrated promising efficacy in animal models of genital herpes. However, the immunogenicity, protective efficacy, and non-replicative status of the highly purified clinical vaccine candidate (HSV529) derived from dl5-29 have not been evaluated. Humoral and cellular immune responses were measured in mice and guinea pigs immunized with HSV529. Protection against acute and recurrent genital herpes, mortality, latent infection, and viral shedding after vaginal HSV-2 infection was determined in mice or in naïve and HSV-1 seropositive guinea pigs. HSV529 replication and pathogenicity were investigated in three sensitive models of virus replication: severe combined immunodeficient (SCID/Beige) mice inoculated by the intramuscular route, suckling mice inoculated by the intracranial route, and vaginally-inoculated guinea pigs. HSV529 immunization induced HSV-2-neutralizing antibody production in mice and guinea pigs. In mice, it induced production of specific HSV-2 antibodies and splenocytes secreting IFNγ or IL-5. Immunization effectively prevented HSV-2 infection in all three animal models by reducing mortality, acute genital disease severity and frequency, and viral shedding. It also reduced ganglionic viral latency and recurrent disease in naïve and HSV-1 seropositive guinea pigs. HSV529 replication/propagation was not detected in the muscles of SCID/Beige mice, in the brains of suckling mice, or in vaginal secretions of inoculated guinea pigs. These results confirm the non-replicative status, as well as its immunogenicity and efficacy in mice and guinea pigs, including HSV-1 seropositive guinea pigs. In mice, HSV529 produced Th1/Th2 characteristic immune response thought to be necessary for an effective vaccine. These results further support the clinical investigation of HSV529 in human subjects as a prophylactic vaccine.     

Effect of immunosuppression on experimental Argentine hemorrhagic fever in guinea pigs.

Immunosuppression with cyclosporin A or cyclophosphamide had no apparent effect on the disease course of guinea pigs infected with a virulent strain of Junin virus. Immunosuppression of guinea pigs infected with an attenuated strain of Junin virus led to fulminating Argentine hemorrhagic fever. All immunosuppressed infected animals died. Virus distribution patterns in target organs, as determined by plaque assay and fluorescent antibody procedures, were similar to those from non-immunosuppressed animals infected with a virulent strain. Histopathological lesions in immunosuppressed guinea pigs infected with an attenuated strain of virus were similar to those in non-immunosuppressed guinea pigs infected with a virulent strain. Histological changes attributable to the immunosuppressive drug(s) were regularly observed. Immunosuppressed animals infected with attenuated Junin virus and non-immunosuppressed animals infected with virulent virus failed to develop antibody or responded at a minimal level. Virus-specific cytotoxic spleen cell activity, previously shown to be antibody dependent, failed to develop in the same animals. The presence of a competent immune response, probably serum antibody, determined whether Argentine hemorrhagic fever infection of the guinea pig was lethal or whether recovery ensued; no evidence for harmful effects of the immune response was obtained.     

Saponin Adjuvants. Vi. The Adjuvant Activity of Quil a in Trivalent Vaccination of Cattle and Guinea Pigs Against Foot-And-Mouth Disease

The saponin adjuvant Quil A was investigated in trivalent vaccination against foot-and-mouth disease with a concentrated vaccine based on BHK suspension cell virus of the serotypes O, A and G. The activity in cattle was estimated on the basis of seroneutra-lizing antibodies. Five and 10 ml doses with or without 1 mg of Quil A were each injected into 6 animals. Seroneutralizing antibodies were estimated at regular intervals during a period of 29 weeks. The activity in guinea pigs was estimated by experimental challenge. One ml doses of serial 4-fold dilutions of the vaccine with or without 50 µg of Quil A were injected into 24 groups of 20 guinea pigs. Challenge was given 3 weeks after vaccination. It was concluded that Quil A showed adjuvant activity in cattle and guinea pigs with all the serotypes used in the trivalent vaccination.     

Differential immune responses and protective efficacy induced by components of a tuberculosis polyprotein vaccine, Mtb72F, delivered as naked DNA or recombinant protein

Key Ags of Mycobacterium tuberculosis initially identified in the context of host responses in healthy purified protein derivative-positive donors and infected C57BL/6 mice were prioritized for the development of a subunit vaccine against tuberculosis. Our lead construct, Mtb72F, codes for a 72-kDa polyprotein genetically linked in tandem in the linear order Mtb32(C)-Mtb39-Mtb32(N). Immunization of C57BL/6 mice with Mtb72F DNA resulted in the generation of IFN-gamma responses directed against the first two components of the polyprotein and a strong CD8(+) T cell response directed exclusively against Mtb32(C). In contrast, immunization of mice with Mtb72F protein formulated in the adjuvant AS02A resulted in the elicitation of a moderate IFN-gamma response and a weak CD8(+) T cell response to Mtb32c. However, immunization with a formulation of Mtb72F protein in AS01B adjuvant generated a comprehensive and robust immune response, resulting in the elicitation of strong IFN-gamma and Ab responses encompassing all three components of the polyprotein vaccine and a strong CD8(+) response directed against the same Mtb32(C) epitope identified by DNA immunization. All three forms of Mtb72F immunization resulted in the protection of C57BL/6 mice against aerosol challenge with a virulent strain of M. tuberculosis. Most importantly, immunization of guinea pigs with Mtb72F, delivered either as DNA or as a rAg-based vaccine, resulted in prolonged survival (>1 year) after aerosol challenge with virulent M. tuberculosis comparable to bacillus Calmette-Guérin immunization. Mtb72F in AS02A formulation is currently in phase I clinical trial, making it the first recombinant tuberculosis vaccine to be tested in humans.     

Effects of X-irradiation on the immune response of guinea pigs to Q fever vaccine

The immune response of guinea pigs to Q fever vaccine following 75 to 250 R (60 to 180 rads) of acute whole-body irradiations was investigated. Complement-fixing (CF) antibody titers and protection against febrile response to challenge with virulent Coxiella burnetii were studied. Exposures ranging from 75 to 250 R, 24 hours prior to inoculation, did not detectably alter the CF antibody response. Similar results were observed with 175 R delivered 48 or 72 hours before immunization. Protection against febrile response to challenge with 10(3) median fever doses of C. burnetii was seen in animals irradiated with 175 R, 24 or 72 hours before immunization. Significant protection was detectable at 14, 21, and 42 days after immunization in both irradiated and nonirradiated animals. Acute irradiation of the degree studied increases the mortality in normal animals infected 15 to 17 days later with virulent C. burnetii. The lethal effect could be prevented by use of Q fever vaccine.     

Murine model for immunoprophylaxis of cytomegalovirus infection. I. Efficacy of immunization.

Murine cytomegalovirus was utilized as a model for human cytomegalovirus, which had no experimental animal, to study immunoprophylaxis of the cytomegalovirus infections. (1) Murine cytomegalovirus (MCMV) serially propagated in mouse embryonic fibroblasts had lost pathogenicity for weanling mice including neonatally thymectomized mice. (2) The cell culture-adapted MCMV was effective as a "live, attenuated virus vaccine" against challenge by virulent, mouse-passaged MCMV. (3) The immunization via intraperitoneal route protected mice from every parameter of MCMV infection. These included clinical signs, virus replication, histopathology and mortality. (4) The protective immunity was active against the virulent MCMV which was not neutralized by the rabbit anti-attenuated MCMV serum.     

Ebola GP-specific monoclonal antibodies protect mice and guinea pigs from lethal Ebola virus infection

Ebola virus (EBOV) causes acute hemorrhagic fever in humans and non-human primates with mortality rates up to 90%. So far there are no effective treatments available. This study evaluates the protective efficacy of 8 monoclonal antibodies (MAbs) against Ebola glycoprotein in mice and guinea pigs. Immunocompetent mice or guinea pigs were given MAbs i.p. in various doses individually or as pools of 3-4 MAbs to test their protection against a lethal challenge with mouse- or guinea pig-adapted EBOV. Each of the 8 MAbs (100 μg) protected mice from a lethal EBOV challenge when administered 1 day before or after challenge. Seven MAbs were effective 2 days post-infection (dpi), with 1 MAb demonstrating partial protection 3 dpi. In the guinea pigs each MAb showed partial protection at 1 dpi, however the mean time to death was significantly prolonged compared to the control group. Moreover, treatment with pools of 3-4 MAbs completely protected the majority of animals, while administration at 2-3 dpi achieved 50-100% protection. This data suggests that the MAbs generated are capable of protecting both animal species against lethal Ebola virus challenge. These results indicate that MAbs particularly when used as an oligoclonal set are a potential therapeutic for post-exposure treatment of EBOV infection.     

Immunological evaluation of mannosylated chitosan nanoparticles based foot and mouth disease virus DNA vaccine,pVAC FMDV VP1–OmpA in guinea pigs

A DNA vaccine for foot and mouth disease (FMD) based on mannosylated chitosan nanoparticles was evaluated in guinea pigs. The DNA construct was comprised of FMD virus full length-VP1 gene and outer membrane protein A (Omp A) gene of Salmonella typhimurium as a Toll-like receptor (TLR)-ligand in pVAC vector. Groups of guinea pigs immunized either intramuscularly or intra-nasally were evaluated for induction of virus neutralizing antibodies, Th1(IgG2) and Th2 (IgG1) responses, lymphocyte proliferation, reactive nitrogen intermediate production, secretory IgA for naso-mucosal immune response and protection upon homotypic type O virulent FMD virus challenge. The results indicate the synergistic effect of OmpA on the immunogenic potential of FMD DNA vaccine construct delivered using mannosylated chitosan nano-particles by different routes of administration. These observations suggest the substantial improvement in all the immunological parameters with enhanced protection in guinea pigs.     

Effect of the Route of Inoculation on Antibody Formation in Guinea Pigs Immunized with Parainfluenza Virus Vaccines

The efficiency of the intramuscular route of immunization of guinea pigs was compared with the intraperitoneal route when trivalent parainfluenza virus vaccine was employed as immunogen. When the routes of immunization were compared by effective dose 50, the intramuscular route was more effective. Likewise, a statistical evaluation of conversion rates and of titers revealed significantly higher values for the intramuscular than for the intraperitoneal route to all three components in two of the lots of vaccine tested.     

Gamma-Irradiated Venezuelan Equine Encephalitis Vaccines

The efficacy of Formalin-inactivated Venezuelan equine encephalitis (VEE) vaccine has been reported to be low for man. Although a live VEE vaccine has been shown to be highly effective for the protection of laboratory workers, local and systemic reactions have occurred in approximately 20% of inoculated individuals. Therefore, studies were initiated in an attempt to produce an inactivated vaccine of high potency with low toxicity. Inactivated VEE vaccines were prepared by exposing virus suspensions to 8 x 10(6) or 10 x 10(6) r of gamma radiation. Irradiated VEE vaccines prepared from virus suspensions produced in Maitland-type chick embryo (MTCE) cell cultures and in monolayer cultures of human diploid strain WI-38 cells were highly immunogenic for mice and guinea pigs. Guinea pigs vaccinated with a series of three inoculations of vaccine (MTCE) survived challenge with at least 10(8.4) mouse intracerebral 50% lethal doses of VEE virus. Irradiated vaccines induced high levels of serum-neutralizing and hemagglutinin-inhibiting antibodies in guinea pigs and rabbits. These findings suggest that ionizing radiation may be effective in the preparation of an inactivated VEE vaccine.     

Chimeric virus-like particles elicit protective immunity against serotype O foot-and-mouth disease virus in guinea pigs

Foot-and-mouth disease (FMD) is an acute and highly contagious disease caused by foot-and-mouth disease virus (FMDV) that can affect cloven-hoofed animal species, leading to severe economic losses worldwide. Therefore, the development of a safe and effective new vaccine to prevent and control FMD is both urgent and necessary. In this study, we developed a chimeric virus-like particle (VLP) vaccine candidate for serotype O FMDV and evaluated its protective immunity in guinea pigs. Chimeric VLPs were formed by the antigenic structural protein VP1 from serotype O and segments of the viral capsid proteins (VP2, VP3, and VP4) from serotype A. The chimeric VLPs elicited significant humoral and cellular immune responses with a higher level of anti-FMDV antibodies and cytokines than the control group. Furthermore, four of the five guinea pigs vaccinated with the chimeric VLPs were completely protected against challenge with 100 50% guinea pig infectious doses (GPID₅₀) of the virulent FMDV strain O/MAY98. These data suggest that chimeric VLPs are potential candidates for the development of new vaccines against FMDV.     

Virulence and immunogenicity in experimental animals of Bacillus anthracis strains harbouring or lacking 110 MDa and 60 MDa plasmids

A comparative study was made of the virulence and immunogenicity in mice or guinea pigs of Bacillus anthracis strains harbouring 110 MDa and/or 60 MDa plasmids. Strains cured of the 110 MDa or the 60 MDa plasmid were more than 100-fold less virulent to mice than were the parental strains harbouring these plasmids. Guinea-pigs immunized with plasmid-free derivatives of the non-encapsulated vaccine strain 34F2 showed no resistance to challenge with strain 17JB, which harbours both 110 MDa and 60 MDa plasmids, suggesting that the derivative strains had lost their immunizing ability against anthrax.     

Immunogenicity and Protective Efficacy of a Vero Cell Culture-Derived Whole-Virus H7N9 Vaccine in Mice and Guinea Pigs

BackgroundA novel avian H7N9 virus with a high case fatality rate in humans emerged in China in 2013. We evaluated the immunogenicity and protective efficacy of a candidate Vero cell culture-derived whole-virus H7N9 vaccine in small animal models.MethodsAntibody responses induced in immunized DBA/2J mice and guinea pigs were evaluated by hemagglutination inhibition (HI), microneutralization (MN), and neuraminidase inhibition (NAi) assays. T-helper cell responses and IgG subclass responses in mice were analyzed by ELISPOT and ELISA, respectively. Vaccine efficacy against lethal challenge with wild-type H7N9 virus was evaluated in immunized mice. H7N9-specific antibody responses induced in mice and guinea pigs were compared to those induced by a licensed whole-virus pandemic H1N1 (H1N1pdm09) vaccine.ResultsThe whole-virus H7N9 vaccine induced dose-dependent H7N9-specific HI, MN and NAi antibodies in mice and guinea pigs. Evaluation of T-helper cell responses and IgG subclasses indicated the induction of a balanced Th1/Th2 response. Immunized mice were protected against lethal H7N9 challenge in a dose-dependent manner. H7N9 and H1N1pdm09 vaccines were similarly immunogenic.ConclusionsThe induction of H7N9-specific antibody and T cell responses and protection against lethal challenge suggest that the Vero cell culture-derived whole-virus vaccine would provide an effective intervention against the H7N9 virus.     

A Single Intramuscular Vaccination of Mice with the HSV-1 VC2 Virus with Mutations in the Glycoprotein K and the Membrane Protein UL20 Confers Full Protection against Lethal Intravaginal Challenge with Virulent HSV-1 and HSV-2 Strains

Herpes Simplex Virus type-1 (HSV-1) and type-2 (HSV-2) establish life-long infections and cause significant orofacial and genital infections in humans. HSV-1 is the leading cause of infectious blindness in the western world. Currently, there are no available vaccines to protect against herpes simplex infections. Recently, we showed that a single intramuscular immunization with an HSV-1(F) mutant virus lacking expression of the viral glycoprotein K (gK), which prevents the virus from entering into distal axons of ganglionic neurons, conferred significant protection against either virulent HSV-1(McKrae) or HSV-2(G) intravaginal challenge in mice. Specifically, 90% of the mice were protected against HSV-1(McKrae) challenge, while 70% of the mice were protected against HSV-2(G) challenge. We constructed the recombinant virus VC2 that contains specific mutations in gK and the membrane protein UL20 preventing virus entry into axonal compartments of neurons, while allowing efficient replication in cell culture, unlike the gK-null virus, which has a major defect in virus replication and spread. Intramuscular injection of mice with 10⁷ VC2 plaque forming units did not cause any significant clinical disease in mice. A single intramuscular immunization with the VC2 virus protected 100% of mice against lethal intravaginal challenge with either HSV-1(McKrae) or HSV-2(G) viruses. Importantly, vaccination with VC2 produced robust cross protective humoral and cellular immunity that fully protected vaccinated mice against lethal disease. Quantitative PCR did not detect any viral DNA in ganglionic tissues of vaccinated mice, while unvaccinated mice contained high levels of viral DNA. The VC2 virus may serve as an efficient vaccine against both HSV-1 and HSV-2 infections, as well as a safe vector for the production of vaccines against other viral and bacterial pathogens.