Inactivated FMD Vaccines Research Articles

Intradermal Inoculation of Inactivated Foot-and-Mouth Disease Vaccine Induced Effective Immune Responses Comparable to Conventional Intramuscular Injection in Pigs.

All pigs in the Republic of Korea are given the foot-and-mouth disease virus (FMDV) vaccine intramuscularly (IM) as part of the country's vaccination policy. However, the IM administration of the FMDV vaccine to pig results in residual vaccine components in the muscle and undesirable changes in muscle and soft tissues, causing economic losses in swine production. In this study, we evaluated whether intradermal (ID) vaccination could be proposed as an alternative to IM administration. ID vaccination (0.2 mL on each side of the neck muscle) and IM vaccination (2 mL on each side of the neck muscle) were performed twice, separated by 14 days, using a commercial FMD vaccine in specific-pathogen-free pigs. We observed growth performance, gross and microscopic lesions at the inoculation site, FMDV-specific antibodies, and neutralizing antibodies for 35 days after vaccination. Side effects on the skin grossly appeared following ID administration, but most were reduced within two weeks. All ID-vaccinated pigs showed inflammatory lesions limited to the dermis, but IM-vaccinated pigs had abnormal undesirable changes and pus in the muscle. ID-vaccinated pigs performed comparably to IM-vaccinated pigs in terms of growth, FMD virus-specific antibodies, protection capability against FMDV, and T-cell induction. This study demonstrated that the ID inoculation of the inactivated FMD vaccine induced immune responses comparable to an IM injection at 1/10 of the inoculation dose and that the inoculation lesion was limited to the dermis, effectively protecting against the formation of abnormal undesirable changes in muscle and soft tissues.

Effect of foot-and-mouth disease vaccination on acute phase response and milk production in the Holstein-Friesian crossbred cow

The study investigated the effects of FMD vaccination on acute phase response and milk composition in the HF crossbred cows (n = 12) using a cross-over experimental design. In trial 1, one group (n = 6) received inactivated trivalent oil-adjuvanted FMD vaccine [day post-vaccination, (dpv) 0], while the mock-vaccinated group received saline (n = 6). After a cooling period of 15 days, the trial was repeated by swapping groups. The body temperature, dry matter intake (DMI) and milk yield were recorded. Haemato-biochemical parameters, haptoglobin and cortisol concentrations were also assessed. A significant (p < 0.05) increase in the neutralizing antibody response to FMDV serotype O and Asia1 indicated a positive immune response. A significant (p < 0.05) increase of 0.4° to 0.6°C in the body temperature, decrease of 0.7–0.8 kg in DMI along with an increase in the serum haptoglobin, total leukocyte count and neutrophils within dpv 2 indicated acute phase response in the FMD vaccinated group. Among the milk constituents, only milk fat (p = 0.053) was significant. It was concluded that FMD vaccination induced acute phase response within dpv 3 in the crossbred cows and caused a non-significant reduction in the milk yield on the day of vaccination.

Development of Foot and Mouth Disease Vaccine Formulation in Egypt by Using Silver Nanoparticles as Immunogenic and Adjuvant Corresponding author: Name: Rania Dweek, Tel: 01009377501 E-mail : raniadweek@yahoo.com

ABSTRACTObjective: To evaluate the effect of silver nanoparticles (AgNPs) with FMD inactivated oil adjuvant vaccine on immunological response of cattle.Study Design: Randomized clinical trial. Procedures: Silver nanoparticles (AgNPs) were prepared then added to locally produced inactivated trivalent FMD vaccine used in Egypt. Twenty cattle were classified into 4 groups (5 in each group).The first group was vaccinated by FMD trivalent inactivated oil adjuvant vaccine plus AgNPs (3ml subcutaneously), the second group was vaccinated by FMD trivalent inactivated oil adjuvant vaccine (3ml subcutaneously). The third group was vaccinated by FMD trivalent inactivated vaccine plus AgNPs as adjuvant (2ml subcutaneous). The fourth group was injected by AgNPs only (1 ml subcutaneous). Sera samples were collected from all animals groups for measuring humeral immunity by using serum neutralization test (SNT) and cell mediated immunity by using bovine Interleukin 6 (IL-6) at first ,second, third and fourth week for (IL-6 and SNT) and at 2 months and 4 months for SNT.Results: The size of AgNPs by TEM (Transmission Electron Microscope) is ranged from 5.8 to 28.51 nm. Antibody titer by SNT revealed that first group was the highest group reach to protective value at 2 weeks (1.538 log10) and reach to peak at 2 months (2.77 log10). Bovine IL-6 was revealed that animals vaccinated by AgNPs appear more quickly than that vaccinated by FMD inactivated oil adjuvant vaccine. Conclusion: The beneficial effect of AgNPs to potentiate both cellular and humeral immunity against FMD.

Effect of Carbomer as an Adjuvant for Enhancement of Immune-Response Against FMD Vaccine

This work was designed to provide high protective, long-lasting immunity against FMD by enhancing the immunogenicity of the trivalent FMD vaccine using carbomer as adjuvant using G. pigs as an alternative cheapest animal model for quality control testing of the prepared FMD vaccines formulae. Guinea pigs were chosen as experimental models to develop concepts and techniques to study the PD50 of FMD vaccines because of the similarities of clinical symptoms in these animals to those of swine and cattle to saving cost, three different formulae of inactivated trivalent FMD vaccine including serotypes O Pan Asia2, A Iran O5 and SAT2/EGY/2012 were prepared as formula 1- (50% carbomer to 50% antigen); formula 2 (50% Montanide ISA 206 to 50%antigen) and formula 3- (25% Montanide ISA 206 and 25% carbomer with 50 % antigen). All of such formulae were found to be free from foreign contaminants, safe and potent, showing no postvaccinal reactions and high protective levels of specific FMD antibodies in Guinea pigs. Each vaccine formula's immunogenicity was determined by estimation of 50% Guinea pig protective dose (GPPD50) and monitoring of the humeral antibody response of vaccinated G. Pig groups. It was found that Montanide oils 206 with carbomer is the best vaccine formula, followed by Montanide oils 206 and finally carbomer which give early short-lasting immunity.

Layered double hydroxide nanoparticles as an adjuvant for inactivated foot-and-mouth disease vaccine in pigs

BackgroundFoot-and-mouth disease (FMD) is a highly transmissible disease that leads to vast economic losses in many countries. Prevention using inactivated vaccines is one effective measure used to control FMD. Unfortunately, inactivated FMD vaccines provide only short-term protection and require a cold-chain system. In recent years, many studies have shown that layered double metal hydroxides (LDHs) carrying antigens can be used to strongly induce immune responses. In this study, LDH nanoparticles (NPs) were prepared by hydrothermal synthesis. LDH particle size, electric potential, and morphology were measured and observed. The adsorption capacity of LDH NPs to FMDV was tested. The effects of LDH as an adjuvant on inactivated FMDV vaccines were further evaluated and compared with commercial FMDV Montanide ISA-206 in BALB/C female mice and Yorkshire pigs.ResultsLDH NPs were successfully prepared with a uniform particle size of ~ 87.21 nm, regular edges, a loose hexagonal shape and positive zeta charge of 32 mV. The maximum absorption concentration was 0.16–0.31 μg FMDV/μg LDH. In the mouse experiment, antibody levels in group LDH + FMDV were significantly higher compared to group saline + FMDV (P < 0.01) from days 42–98 and were significantly higher to group ISA-206 + FMDV on day 56 post-immunization (P < 0.05). After day 14 post-immunization, IFN-γ content was significantly increased (P < 0.05). In the pig experiment, antibody levels in both the ISA-206 + FMDV and LDH + FMDV were positive and were significantly higher compared with the PBS group on day 7 (P < 0.005). Antibody levels in 90% pigs were positive on day 56 in the LDH group. The neutralizing antibody levels in the LDH and ISA-206 groups were significantly higher from days 7–28 compared to the PBS control group (P < 0.05). Thus, LDH NPs were effective at inducing an immune response against FMDV.ConclusionsLDHs with a loose hexagonal shape and a positive charge were prepared and evaluated as adjuvant for FMD vaccine. It was demonstrated that LDHs can induce immune responses in mice and pigs. In addition, the LDHs produced antibodies continuously which may indicate a slow-release effect. The study shows that LDHs may act as a potentially useful FMDV adjuvant.

Studies on development of early immunity against type O FMD in naturally susceptible animals

FMD risk in the Russian Federation dictates the need for enhanced measures aiming to prevent the introduction of FMD virus and comprising systematic monitoring research and mass vaccination of susceptible animals in the buffer zone. Research into the development of vaccines for early protection confirm that their use induces the formation of virus-neutralizing antibodies in naturally susceptible animals in the outbreak area, which protects from FMD infection, limits its spread and contains it within the primary outbreak. Taking into account the high speed of the infection spread, such a control measure as using FMD vaccines which induce early protection should be adopted immediately after the occurrence of the outbreak. The article presents the results of the research into the formation of humoral immunity in naturally susceptible animals triggered by administration of inactivated emulsion FMD vaccines capable of ensuring early protection against type O FMD. Culture FMD virus of О/Primorsky/2012, О/Saudi Arabia/08 and О/Mongolia/2017 strains was used for vaccine production. Immunogenic activity of vaccines was tested in cattle, pigs, and sheep. It was found that monovalent emulsion FMD vaccine based on О/Mongolia/2017 strain induced the formation of virus-neutralizing antibodies in the quantity necessary to protect against the homologous strain in seven days after a single administration in the dose of 2 cm3 . Vaccines based on О/Saudi Arabia/08 and О/Primorsky/2012 FMDV strains can protect animals from infection with heterologous О/Mongolia/2017 strain at early stages if a double dose is administered. Vaccines based on the above-mentioned strains induce early immunity formation (seven days after vaccination) against type O FMD. We suggest using the given products in the zones of a higher risk of the virus introduction.

Efficacy of a foot-and-mouth disease vaccine against a heterologous SAT1 virus challenge in goats

Goats are susceptible to infection with foot-and-mouth disease virus (FMDV), but their role in the epidemiology of the disease and response to vaccination is poorly understood. In southern Africa, FMDV serotypes Southern African Territories (SAT) 1, 2 and 3 are known to be endemic. In this study, we evaluated the efficacy of a pentavalent FMD vaccine in goats against heterologous challenge with a pool of field SAT1 FMDV. Forty FMD sero-negative goats (6–12 months of age) of mixed sexes were randomly allocated to one of five treatment groups: full cattle dose (2 ml), 1/3rd (0.67 ml), 1/6th (0.33 ml), 1/12th (0.16 ml) or unvaccinated placebo control. Goats were vaccinated with an inactivated pentavalent FMD vaccine containing serotypes SAT1, SAT2 and SAT3 on day 0 and revaccinated at day 20 post vaccination. Thereafter, thirty-four goats were challenged by tongue inoculation at day 41 post-vaccination using 104.57 50% tissue culture infective dose (TCID50) FMDV SAT1 pool. Animals were examined daily and clinical signs were scored. Rectal temperatures were measured daily, with temperatures ≥40 °C defined as fever. Clinical specimens (nasal, oral and rectal swabs) were collected on days 0, 2, 4 and 6 post challenge. Viral shedding was determined using reverse-transcriptase real-time PCR. None of the goats vaccinated with the full cattle dose developed secondary lesions. All vaccinated groups had lower temperatures compared to the unvaccinated controls (P < 0.001). Based on RT-PCR results, goats in the unvaccinated control group shed more virus compared to all groups except for 1/12th (P < 0.05), while goats in the full dose group shed less virus than goats in the 1/12th and the unvaccinated control group (P < 0.05). The results suggest that the 1/3rd (0.67 ml) dose of the vaccine is sufficient to reduce viral shedding after heterologous challenge with a FMDV SAT1 pool.

Engineering viable foot-and-mouth disease viruses with increased acid stability facilitate the development of improved vaccines

Foot-and-mouth disease virus (FMDV), the most acid-unstable virus among picornaviruses, tends to disassemble into pentamers at pH values slightly below neutrality. However, the structural integrity of intact virion is one of the most important factors that influence the induction of a protective antibody response. Thus, improving the acid stability of FMDV is required for the efficacy of vaccine preparations. According to the previous studies, a single substitution or double amino acid substitutions (VP1 N17D, VP2 H145Y, VP2 D86H, VP3 H142D, VP3 H142G, and VP1 N17D + VP2 H145Y) in the capsid were introduced into the full-length infectious clone of type O FMDV vaccine strain O/HN/CHN/93 to develop seed FMDV with improved acid stability. After the transfection into BSR/T7 cells of constructed plasmids, substitution VP1 N17D or VP2 D86H resulted in viable and genetically stable FMDVs, respectively. However, substitution VP2 H145Y or VP1 N17D + VP2 H145Y showed reverse mutation and additional mutations, and substitution VP3 H141G or VP3 H141D prevented viral viability. We found that substitution VP1 N17D or VP2 D86H could confer increased acid resistance, alkali stability, and thermostability on FMDV O/HN/CHN/93, whereas substitution VP1 N17D was observed to lead to a decreased replication ability in BHK-21 cells and mildly impaired virulence in suckling mice. In contrast, substitution VP2 D86H had no negative effect on viral infectivity. These results indicated that the mutant rD86H carrying substitution VP2 D86H firstly reported by us could be more adequate for the development of inactivated FMD vaccines with enhanced acid stability.

Artificially designed hepatitis B virus core particles composed of multiple epitopes of type A and O foot-and-mouth disease virus as a bivalent vaccine candidate.

Recently, many countries, including China, have experienced a series of type A and O foot-and-mouth disease virus (FMDV) epidemics, causing serious economic losses. Although concerns about the safety of inactivated FMD vaccines have been raised, the development of a safe and effective subunit vaccine is necessary. We constructed two chimeric virus-like particles (VLPs; rHBc/AO and rHBc/AOT VLPs) displaying tandem repeats of B cell epitopes (VP1 residue 134-161 and 200-213) derived from type A and O FMDV and one T cell epitope (3 A residue 21-35) using the truncated hepatitis B virus core (HBc) carrier. Our results indicate that the chimeric HBc can self-assemble into VLPs with these FMDV epitopes displayed on the surface. Immunization with the chimeric VLPs induced specific IgG and neutralization antibodies against type A and O FMDV in mice. Compared with the commercial type A/O FMDV bivalent inactivated vaccine, rHBc/AO and rHBc/AOT VLPs significantly stimulated the production of Th1 type cytokines (IFN-γ and IL-2), whereas Th2 cytokine production (IL-4 and IL-10) was decreased. Compared with rHBc/AO, rHBc/AOT induced increased Th2 cytokine and specific IgG production. These results demonstrate that the VLPs constructed in the current study induced both humoral and cellular immune responses and may represent potential bivalent VLP vaccines targeting both FMDV type A and O strains.

Synthetic RNA derived from the foot-and-mouth disease virus genome elicits antiviral responses in bovine and porcine cells through IRF3 activation

Foot-and-mouth disease virus (FMDV) is the causative agent of a highly transmissible disease affecting wild and domestic animals including pigs, cattle and sheep. The ability of synthetic RNA transcripts mimicking distinct domains in the non-coding regions of the FMDV genome (ncRNAs) to induce a potent innate immune response in swine cultured cells and mice has been previously described, as well as their enhancing effect on conventional inactivated FMD vaccines. Here, we provide evidence of the activation of interferon regulatory factor 3 (IRF3), a key transcriptional regulator of type I interferon (IFN)-dependent immune responses after transfection of swine and bovine cells with transcripts corresponding to the FMDV 3´ non-coding region (3´NCR). Induction of IFN-β and Mx1expression, concomitantly with antiviral activity and IRF3 activation was observed in bovine MDBK cells transfected with the 3´NCR. Our results link the stimulation of the innate immune response observed in 3´NCR-transfected cells to the intracellular type I IFN signaling pathway and suggest the potential use of these molecules for antiviral strategies in cattle.

Enhanced protection against FMDV in cattle after prime- boost vaccination based on mucosal and inactivated FMD vaccine

Improved immunization and control strategies and platforms are greatly needed for foot and mouth disease virus (FMDV) and mucosal vaccines propose an effective strategy for the control FMDV by blocking viral entry. In this study, several immunization strategies, using two FMDV vaccine formulations, including Montanide ISA 206 oil-based FMD inactivated vaccine and Montanide IMS 1313 VG N PR-based concentrated semi-purified FMD mucosal vaccine, were applied. Results of intranasal immunization with the prepared FMD mucosal vaccine, given once or twice, induced IgA levels in both nasal and salivary secretions besides a high response of lymphocyte proliferation with protection levels reaching 20% and 40%, respectively, in a challenge trial in cattle. Immunization with Montanide 206 inactivated FMD vaccine was capable of inducing 80% protection whereas prime-boost strategy based on the administration of mucosal vaccine followed by inactivated vaccine appeared to be the most potent strategy by achieving 100% protection against an FMDV challenge. Indeed, the study reports the efficacy of the prepared IMS 1313 FMD mucosal vaccine and the possible use of this vaccine in the context of different vaccination strategies to control FMDV.

Adjuvantation of inactivated Foot and Mouth Disease Virus vaccine with IL-15 expressing plasmid improves the immune response in Guinea Pigs

Foot and mouth disease is a highly contagious disease affecting cloven footed animals. Vaccination using inactivated virus is followed to control the disease. As the immune response conferred by the inactivated vaccine is short lived, there is a need for an alternate vaccine with increased duration of immunity. Inclusion of adjuvant which enhances B and T cell responses is one of the strategies to increase the duration of immune responses of the vaccine. Interleukin 15 is one such a cytokine which improves the cell mediated immune response and also involved in the maintenance of memory T and B cells. In the present communication, we evaluated the role of bovine IL-15 as an adjuvant to inactivated FMD vaccine in guinea pig model. Animals injected with FMD inactivated vaccine and IL-15 plasmid showed improved levels of neutralizing antibodies which were maintained up to 6 months (as the level of neutralizing antibodies is more >1.5 which is considered to give protection). Increased Th1 and Th2 responses (by measuring the level of IL-4 and IFN- gamma responses) were seen in IL-15 adjuvanted guinea pigs compared to animals injected with inactivated vaccine alone.

Role of a single amino acid substitution of VP3 H142D for increased acid resistance of foot-and-mouth disease virus serotype A.

Foot-and-mouth disease virus (FMDV) particles lose infectivity due to their dissociation into pentamers at pH value below 6.5. After the uptake of FMDV by receptor-mediated endocytosis, the acid-dependent dissociation process is required for the release of FMDV genome inside endosomes. Nevertheless, dissociation of FMDV particles in mildly acidic conditions renders the inactivated FMD vaccine less effective. To improve the acid stability of inactivated FMD vaccine during the manufacturing process, a serotype A IND 40/2000 (in-use vaccine strain) mutant with increased resistance to acid inactivation was generated through reverse genetics approach. Based upon the earlier reports, the crucial amino acid residue, H142 of VP3 capsid protein was substituted separately to various amino acid residues Arg (R), Phe (F), Ala (A), and Asp (D) on the full-genome length cDNA clone. While the H142→R or H142→F or H142→A substitutions resulted in non-infectious FMDV, H142→D mutation on VP3 protein (H3142D) resulted in the generation of mutant virus with enhanced resistance to acid-induced inactivation. In addition, H3142D substitution did not alter the replication ability and antigenicity of mutant as compared to the parental virus. However, the virus competition experiments revealed that the H3142D substitution conferred a loss of fitness for the mutant virus. Results from this study demonstrate that the H3142D substitution is the molecular determinant of acid-resistant phenotype in FMDV serotype A.

Immunostimulant Activity of Levamisole to Polyvalent FMD Vaccine in Buffaloes

In Egypt, many challenges facing eradication strategy of FMD concerning the short term immunity induced by inactivated polyvalent FMD vaccine. The aim of the study was directed to ascertain whether post vaccination antibodies against FMDV in buffaloes could be enhanced by administration with levamisole. To achieve the goal, 24 buffaloes were divided into 4 groups, G1 is non vaccinated non adjuvanted group, G2 is vaccine control group, G3 is simultaneously FMD vaccinated and levamisole stimulated group and G4 is FMD vaccinated 7 days after levamisole stimulation. Blood samples were examined for 16 succesive weeks post vaccination for FMD antibodies to serotypes O, A and SAT-2 by ELISA test. The results revealed that animalssimultinously vaccinated and treated with levamisole was higher than the group adjuvinated with levamisole 7 days before FMD vaccination. Levamisole has stimulant effect on the vaccinalimmunity of buffaloes to FMD serotypes O, A and SAT2. Antibody titers of FMD in animal groups were parallel in each group with a high titer in serotype A than O and SAT2. Further investigations are needed to explore the effect of levamisole on cell mediated immune response and challenge test in buffaloes.

Serological response of commercial dairy cattle to inactivated foot-and-mouth disease vaccine (type-O &amp; A) in Nigeria

An observational study was conducted in a peri-urban dairy establishment in Jos South, Plateau State Nigeria to determine immune response of dairy cattle to commercial inactivated foot-and-mouth disease vaccine serotypes (O and A). Thirty seven Friesian cattle aged ?2years old with their crosses (15 selected pre-vaccination and 22 selected 21 days post-vaccination) were investigated for immune response to vaccination with an inactivated trivalent FMD vaccine containing serotypes O, A and SAT 2). Sera collected on day 0 pre-vaccination and 21 days post-vaccination was tested for structural protein antibodies to FMD serotypes O and A using the Solid Phase Competitive ELISA assay. The mean OD value for serum end point titre of FMD serotype O pre-vaccination was 11.64% with 6.67% (95%CI: 0.33 – 28.73) of the selected cattle being seropositive, at 21 days post-vaccination the mean OD value in selected cattle was 52.83% with 68.18% (95%CI: 46.95 – 84.89) of the selected cattle seropositive. For the FMD serotype A, 26.67% (95%CI: 9.10 – 52.53) of the selected cattle were seropositive pre-vaccination with a mean OD value of 29.21% and by 21 days post-vaccination, 72.73% (95%CI: 51.67 – 88.13) of the selected cattle were seropositive with a mean OD value of 61.70%. Serological response to vaccination improved in most selected cattle by 21 days post-vaccination. This study result has indicated that commercial inactivated FMD vaccines used for the prophylactic control of FMD in commercial dairy farm in Nigeria provoked immune response after a single shot.Asian J. Med. Biol. Res. June 2015, 1(2): 163-168

Validation of γ-radiation and ultraviolet as a new inactivators for foot and mouth disease virus in comparison with the traditional methods.

Aim:The present work deals with different methods for foot and mouth disease virus (FMDV) inactivation for serotypes O/pan Asia, A/Iran05, and SAT-2/2012 by heat, gamma radiation, and ultraviolet (UV) in comparison with the traditional methods and their effects on the antigenicity of viruses for production of inactivated vaccines.Materials and Methods:FMDV types O/pan Asia, A/Iran05, and SAT-2/2012 were propagated in baby hamster kidney 21 (BHK21) and titrated then divided into five parts; the first part inactivated with heat, the second part inactivated with gamma radiation, the third part inactivated with UV light, the fourth part inactivated with binary ethylamine, and the last part inactivated with combination of binary ethylamine and formaldehyde (BEI+FA). Evaluate the method of inactivation via inoculation in BHK21, inoculation in suckling baby mice and complement fixation test then formulate vaccine using different methods of inactivation then applying the quality control tests to evaluate each formulated vaccine.Results:The effect of heat, gamma radiation, and UV on the ability of replication of FMDV “O/pan Asia, A/Iran05, and SAT-2/2012” was determined through BHK cell line passage. Each of the 9 virus aliquots titer 108 TCID50 (3 for each strain) were exposed to 37, 57, and 77°C for 15, 30, and 45 min. Similarly, another 15 aliquots (5 for each strain) contain 1 mm depth of the exposed samples in petri-dish was exposed to UV light (252.7 nm wavelength: One foot distance) for 15, 30, 45, 60, and 65 min. Different doses of gamma radiation (10, 20, 25, 30, 35, 40, 45, 50, 55, and 60 KGy) were applied in a dose rate 0.551 Gy/s for each strain and repeated 6 times for each dose. FMDV (O/pan Asia, A/Iran05, and SAT-2/2012) were inactivated when exposed to heat ≥57°C for 15 min. The UV inactivation of FMDV (O/pan Asia and SAT-2) was obtained within 60 min and 65 min for type A/Iran05. The ideal dose for inactivation of FMDV (O/pan Asia, A/Iran05, and SAT-2/2012) with gamma radiation were 55-60 and 45 kGy, respectively. Inactivation of FMDV with binary was 20, 24 and 16 hr for O/pan Asia, A/Iran05, and SAT-2/2012, respectively while inactivation by (BEI+FA) was determined after 18, 19 and 11 hr for O/pan-Asia, A/Iran 05, and SAT-2/2012, respectively. The antigenicity of control virus before inactivation was 1/32, it was not changed after inactivation in case of gamma radiation and (BEI+FA) and slightly decrease to 1/16 in case of binary and declined to 1/2, 1/4 in case of heat and UV inactivation, respectively. The immune response induced by inactivated FMD vaccines by gamma radiation and (BEI+FA) lasted to 9 months post-vaccination, while the binary only still up to 8 months post-vaccination but heat and UV-inactivated vaccines were not effective.Conclusion:Gamma radiation could be considered a good new inactivator inducing the same results of inactivated vaccine by binary with formaldehyde (BEI+FA).

Protective immune response to liposome adjuvanted high potency foot-and-mouth disease vaccine in Indian cattle

BackgroundFoot-and-mouth disease (FMD) vaccines applied for prophylactic use in endemic areas provide short-lived immunity requiring regular boosters. Indian FMD control program recommends twice a year vaccination. Development of high potency vaccines that provide better immune response can singificantly contribute to control programme by reducing the frequency of vaccination. The present study explores new adjuvants to enhance the protective efficacy of inactivated trivalent FMD vaccines. Methodology and principal findingsVacciMax® is a novel adjuvant which uses a liposome-based oil emulsion platform. Cattle were immunized using VacciMax-A and VacciMax-B FMD vaccines and evaluated for protective efficacy. Similar groups of animals were also boosted after 6 months to study the effect of booster immunisation on protection against homologous challenge. Serum samples from immunized animals were tested by virus neutralization test (VNT) and liquid phase blocking ELISA (LPBE). After challenge, animals were screened for virus load by real-time PCR and reactivity in non-structural protein (3ABC) antibody detection ELISA to corroborate the protection data. A single dose of VacciMax-A formulation elicited higher percentage protection (63%) in VacciMax-A compared to 25% in VacciMax-B upon challenge at one-year post-vaccination. Upon boosting at 6 months also, VacciMax-A group showed higher levels of protection (100%) compared to VacciMax-B (86%), even though both the groups elicited comparable VNT titre (p=0.4964). The results also demonstrated that intramuscular route was preferrable over subcutaneous route of administration. ConclusionThe study demonstrates that immunization with VacciMax-A-IM adjuvanted FMD vaccine with high antigen payload under boosting regimen could effectively be used as potent vaccine to maintain herd immunity.

Selection and characterization of an acid-resistant mutant of serotype O foot-and-mouth disease virus

Foot-and-mouth disease virus (FMDV) loses infectivity and immunogenicity due to its disassembly in culture environments below pH 6.8. To study the molecular basis of viral resistance to acid-induced disassembly and improve the acid stability of inactivated FMD vaccines during the manufacturing process, type O FMDV mutants with increased resistance to acid inactivation were selected, and the genes encoding their capsid proteins were sequenced. Three amino acid substitutions (VP1 N17D, VP2 D86A, and VP4 S73N) were found in all of the mutants. When these substitutions were introduced into seven infectious FMDV clones alone or combined, a single amino acid substitution in the VP1 protein, N17D, which also appears in type C FMDV acid-resistant mutants, was found to be responsible for the increased resistance to acid inactivation for type O FMDV. In addition, although viral fitness was reduced under standard culture conditions, viral growth kinetics and virulence were not significantly altered in the rescued mutant virus rN17D with the VP1 N17D substitution. Importantly, the N17D substitution could confer improved immunogenicity to the mutant virus rN17D under acidic conditions compared with its parental virus O/YS/CHA/05. These results demonstrate that the N17D substitution in VP1 is the molecular determinant of the acid-resistant phenotype in type O FMDV, indicating the potential for use of this substitution to improve the acid stability of inactivated FMD vaccines during the vaccine production process.

Factors affecting the production of foot-and-mouth disease virus in deep suspension cultures of BHK21 clone 13 cells.

For maximum utilization of deep cultures to produce FMD virus it was important to have adequate control of culture temperature and pH. Culture temperature should be controlled within the range 34·25°7–35°C. and culture pH at 7·2. The culture system became less efficient as the cell concentration was increased from 1 × 106·0 to 9 × 106·0 cells/ml. A cell concentration of 2·5 × 106·0 cells/ml. represented a working compromise between efficiency and antigen titre/ml. for inactivated FMD vaccine production.The input virus/cell ratio had no effect on the time or titre of peak virus yield in the range 1:1 to 1:320. This makes the production of seed virus from small numbers of monolayer cultures feasible and economical.Virus yield was improved by the addition of 5% serum. It would be more satisfactory if a serum-free cell strain could be developed.