ELISA Antibody Titers Research Articles

Reappearance of viral hemorrhagic fever with renal syndrome in northwestern Greece

Minor outbreaks of viral hemorrhagic fever (VHF) with renal failure have occurred in northwestern Greece over past decades. However, during the most recent decade, there has been a paucity of human cases despite the detection of hantavirus in rodents of this area. We present herein the cases of two patients with VHF, arising in the same area, hospitalized for a short period of time. One patient presented with renal failure, while severe hepatic involvement was predominant in the other. Significantly high ELISA antibody titers for hantavirus established the diagnosis. Supportive treatment led to a successful outcome in both cases. We further discuss the difficulties in differential diagnosis of VHF from other zoonoses with similar endemicity, such as leptospirosis. Awareness of the continuing presence of VHF in rural Greece is needed, and a rapid diagnosis is important for the correct therapeutic approach. Continuous surveillance for such diseases, at both the animal (rodents) and human level, is warranted.

Vaxfectin ®, a cationic lipid-based adjuvant for protein-based influenza vaccines

Mice were immunized either with unadjuvanted seasonal trivalent influenza vaccine (TIV) or TIV formulated with Vaxfectin ®, a cationic lipid-based adjuvant. Increasing doses of Vaxfectin ® resulted in increased hemagglutination-inhibition or anti-TIV ELISA antibody titers, with up to a 200-fold increase obtained with 900 μg of Vaxfectin ®. A ≥10-fold dose-sparing effect was demonstrated with Vaxfectin ® formulations. Vaxfectin ® preferentially increased IgG2 titers compared to IgG1 titers, resulting in a balanced IgG isotype distribution. Lower doses of Vaxfectin ® (30 μg) did not enhance antibody responses, but increased the number of IFN-γ secreting T-cells by up to 18-fold. The data demonstrate that Vaxfectin ® enhances Th1 responses with protein-based seasonal influenza vaccine, and suggest that cellular or humoral immune responses may be preferentially induced by modifying the Vaxfectin ®:antigen ratio in the vaccine formulation.

Temporal assessment of seroconversion in response to inactivated foot-and-mouth disease vaccine in Arabian oryx (Oryx leucoryx)

Ten male Arabian oryx (Oryx leucoryx) were vaccinated with a commercially available standard aqueous foot-and-mouth-disease vaccine containing aluminium hydroxide as an adjuvant, and their antibody titres against serotypes O and...

Antigenic, microbicidal and antiparasitic properties of an l-amino acid oxidase isolated from Bothrops jararaca snake venom

Venoms from the bee Apis mellifera, the caterpillar Lonomia achelous, the spiders Lycosa sp. and Phoneutria nigriventer, the scorpions Tityus bahiensis and Tityus serrulatus, and the snakes Bothrops alternatus, Bothrops jararaca, Bothrops jararacussu, Bothrops moojeni, Bothrops neuwiedi, Crotalus durissus terrificus, and Lachesis muta were assayed (800 μg/mL) for activity against Staphylococcus aureus. Venoms from B. jararaca and B. jararacussu showed the highest S. aureus growth inhibition and also against other Gram-positive and Gram-negative bacteria. To characterize the microbicidal component(s) produced by B. jararaca, venom was fractionated through gel exclusion chromatography. The high molecular weight, anti- S. aureus P1 fraction was further resolved by anion exchange chromatography through Mono Q columns using a 0–0.5 M NaCl gradient. Bactericidal Mono Q fractions P5 and P6 showed significant LAAO activity using l-leucine as substrate. These fractions were pooled and subjected to Heparin affinity chromatography, which rendered a single LAAO activity peak. The anti- S. aureus activity was abolished by catalase, suggesting that the effect is dependent on H 2O 2 production. SDS-PAGE of isolated LAAO indicated the presence of three isoforms since deglycosylation with a recombinant N-glycanase rendered a single 38.2 kDa component. B. jararaca LAAO specific activity was 142.7 U/mg, based on the oxidation of l-leucine. The correlation between in vivo neutralization of lethal toxicity (ED 50) and levels of horse therapeutic antibodies anti-LAAO measured by ELISA was investigated to predict the potency of Brazilian antibothropic antivenoms. Six horses were hyperimmunized with Bothrops venoms (50% from B. jararaca and 12.5% each from B. alternatus, B. jararacussu, B. neuwiedii and B. moojeni). To set up an indirect ELISA, B. jararaca LAAO and crude venom were used as antigens. Correlation coefficients ( r) between ED 50 and ELISA antibody titers against B. jararaca venom and LAAO were 0.846 ( p < 0.001) and 0.747 ( p < 0.001), respectively. The hemolytic and leishmanicidal (anti- Leishmania amazonensis) activity of LAAO was also determined.

Western blot can distinguish natural and acquired antibodies to Mycoplasma agassizii in the desert tortoise ( Gopherus agassizii)

Mycoplasma agassizi has been identified as a cause of upper respiratory tract disease (URTD) in the threatened Mojave population of the desert tortoise ( Gopherus agassizii), and anti- M. agassizii antibodies have been found by ELISA in as many as 15% of these animals across their geographic range. Here we report that a cohort of 16 egg-reared desert tortoises never exposed to M. agassizii had ELISA antibody titers to this organism that overlapped with titers obtained from some M. agassizii-infected tortoises. These natural antibodies were predominantly of the IgM class. Western blots of plasma from these non-infected tortoises produced a characteristic banding pattern against M. agassizii antigens. A group of 38 wild-caught desert tortoises was tested by ELISA, and although some of these tortoises had antibody titers significantly higher than the non-infected tortoises, there was considerable overlap at the lower titer levels. However, Western blot analysis revealed distinct banding patterns that could readily distinguish between the non-infected tortoises and tortoises with acquired antibodies, regardless of ELISA antibody titers. We conclude that desert tortoises have natural antibodies to M. agassizii that can compromise the determination of infection status by ELISA. However, the Western blot technique can distinguish between natural and acquired antibody patterns and can be used to confirm the diagnosis of M. agassizii infections in the desert tortoise.

Antibody and T-cell responses to a virosomal adjuvanted H9N2 avian influenza vaccine: Impact of distinct additional adjuvants

A highly efficacious vaccine is required to counteract a threat of an avian influenza pandemic. Increasing the potency of vaccines by adjuvation is essential not only to overcome generally low immunogenicity of pandemic strains, but also to allow dose sparing and as such to make it feasible to satisfy huge global production demands. In this study we evaluated the ability of four distinct adjuvants to further increase immune responses to a virosomal adjuvanted avian H9N2 influenza vaccine in mice. Currently registered adjuvants aluminium phosphate, aluminium hydroxide and MF59, as well as a novel promising adjuvant MATRIX-M were included in the study. Our results demonstrate that all adjuvants significantly increased the H9N2 haemagglutinin (HA) inhibition and ELISA antibody titers induced with the virosomal adjuvanted vaccine. The adjuvants exhibited different effect on the isotype of virus specific antibodies, with MATRIX-M inducing the most pronounced skewing to IgG2a, i.e. towards Th1 type of response. While the virosomal adjuvanted pandemic influenza vaccine efficiently induced CD4 + T-cell response, with no further increase upon adjuvation, the CD8 + T-cell responses induced with virosomal adjuvanted vaccine could be significantly improved upon additional adjuvation with MATRIX-M or MF59. All adjuvants demonstrated a dose sparing effect, i.e. in combination with the virosomal adjuvanted pandemic influenza vaccine they increased immune responses to comparable level independent of the tested vaccine dose. In conclusion, our results demonstrate that immune responses to a virosomal adjuvanted pandemic influenza vaccine can be further enhanced by add-on adjuvants, with MATRIX-M being overall the most potent adjuvant in combination with virosomes, followed by MF59 and finally aluminium-based adjuvants.

Protection of Mice from Rabies by Intranasal Immunization with Inactivated Rabies Virus

The mucosal immunization method is a needle-free alternative way of vaccination. This study evaluated the efficacy of mucosal immunization for rabies. Mice were intranasally administered five times with inactivated and concentrated rabies virus antigen (CRV) supplemented with or without cholera toxin (CT). The anti-rabies virus antibody titer of mice intranasally immunized with CRV plus CT (CRV/CT) was comparable to that of mice intraperitoneally immunized twice with the same amount of CRV. Virus neutralizing (VNA) titers of mice immunized intranasally with CRV/CT were slightly lower than those of intraperitoneally immunized mice. Both anti-rabies virus ELISA antibody and VNA titers of mice immunized with CRV without CT were significantly lower than those of mice immunized with CRV/CT. In mice intranasally immunized with CRV/CT, and intraperitoneally immunized mice, high levels of IgG(2a) antibody were detected, suggesting the activation of Th1-driven cellular immunity by the two ways of immunization. All immunized mice were challenged intracerebrally with a lethal dose of virulent rabies virus CVS strain. The survival rates of mice immunized with CRV/CT and CRV without CT were 67% and 17%, respectively, while the rate of intraperitoneally immunized mice was 100%. Antigen-specific whole IgG and IgG(2a), and VNA titers of survived mice were significantly higher than those of dead mice at the challenge day. These data suggest the possibility of intranasal immunization with inactivated antigen as a rabies vaccination strategy and the importance of a mucosal adjuvant such as CT.

Safety and Efficacy Testing of a Novel Multivalent Bovine Bacterial Respiratory Vaccine Composed of Five Bacterins and Two Immunogens

Bovine bacterial respiratory diseases have been one of the most serious problems due to their high mortality and economic loss in calves. The vaccinations of bovine bacterial respiratory vaccines have been complex because of no multivalent vaccine. In this study, novel multivalent bovine bacterial respiratory vaccine (BRV) was developed and tested for its safety and efficacy. BRV was composed of two immunogens and five bacterins. These were leukotoxoid and bacterin of Mannheimia haemolytica type A, outer membrane protein and bacterin of Pasteurella multocida type A, and bacterins of Haemophilus somnus, Mycoplasma bovis, and Arcanobacterium pyogenes. ELISA antibody titers to five bacterial antigens in vaccinated guinea pigs increased, compared with those in unvaccinated ones. BRV was safe for calves and pregnant cattle in this study. In calves challenged with M. haemolytica and P. multocida, the average daily weight gain and antibody titers of vaccinated calves increased, and respiratory symptoms (P<0.05) and treatment frequency (P<0.01) of vaccinated calves significantly decreased, compared with those of unvaccinated calves. Interestingly, the antibody titers of M. haemolytica leukotoxoid and Mycoplasma bovis were closely related with the reduction of respiratory symptoms. BRV would be an ecomonical measure for the protection against bovine bacterial respiratory diseases.

Comparison of the neutralizing and ELISA antibody titres to measles virus in human sera and in gamma globulin preparations

Measles virus infection as well as measles vaccination induces a long-lasting immune protection. Specific antibodies have been proven to be associated with this immune protection, since measles immunity can be transferred by immune globulin application (passive immunisation). The neutralisation test (NT) is regarded as the gold standard method for measles immunity because it measures functional neutralising antibody, while with the ELISA, which is often based on cell culture grown native virus antigens, predominantly antibodies to the nucleoprotein antigen were detected. To compare the results of NT and ELISA 199 individual sera and 364 gamma globulin samples, which were made from plasma pools, were tested. Qualitative results showed that the sensitivity of the ELISA was 141/144 (97.9%) and specificity was 48/55 (87.3%) when compared to the NT and focused to the patient samples. For the gamma globulin samples the sensitivity and specificity was 100%. As expected no measles NT negative plasma pool samples were found. The present study showed that with increasing NT-titre, the ELISA-values also rise. False negative ELISA results were obtained in 1.5% of patient sera, mainly containing low levels of neutralising antibody. In both antibody tests seropositive specimens revealed a quite good to moderate correlation. Taken together, the measles IgG ELISA is adequately for immunity testing and identifying of seronegative individuals for vaccination.

Protection against H1, H5, H6 and H9 influenza A infection with liposomal matrix 2 epitope vaccines

The recent emergence of multiple avian influenza A subtypes that cause human disease (i.e., H5N1, H9N2 and H7N7), coupled with the fear that one of these strains might precipitate a new pandemic, underscores the need to develop new technological approaches to immunization which elicit protective immune responses against multiple subtypes of influenza A. In response to this demand, several matrix 2 protein ectodomain segments (M2eA) corresponding to the H1N1, H5N1 and H9N2 influenza strains were formulated using a novel liposome-based vaccine technology and evaluated as potential immunogens for developing a “universal” influenza vaccine. Mice immunized with liposomal M2eA survived homologous challenges with H1N1 (100% survival) or H9N2 (80% survival) influenza strains. There were significant reductions in their lung viral load as well as in immunized mice challenged with the H5N1 subtype. The mice vaccinated with an M2eA segment corresponding to the H1N1 and H6N2 (a reassortant influenza A virus carrying the M2eA from PR8/34) strains elicited elevated IgG ELISA antibody titers to this M2eA epitope segment and antiserum from these immunized mice provided passive protection (100% survival) to naïve mice receiving a lethal dose of H6N2 influenza virus. These results provide the first evidence that recombinant M2eA epitopes to multiple subtypes elicited immune protection against a homologous challenge and provides further evidence in favor of the development of a “universal” influenza vaccine based on M2eA.

Effect of Dietary Vitamin E Supplementation on Serum 慣-Tocopherol and Immune Status of Crossbred Calves

An experiment was conducted with twenty crossbred male calves (7-15 days old) divided into 4 different experimental groups on the basis of body weights to study the effect of vitamin E supplementation on the serum α-tocopherol concentration and immune response of the calves. All the calves were fed on milk and calf starter up to 13 weeks and afterwards, they were fed on concentrate mixture and oat hay up to 32 weeks of age. In addition, the calves in groups I, II, III and IV were supplemented with 0, 125, 250 and 500 IU feed grade DL-α-tocopheryl acetate, respectively. Blood samples were collected at 0 day and subsequently at 1, 2, 3, 4, 6 and 8 months of age to monitor the serum α-tocopherol concentration in crossbred calves. After 24 weeks of experimental feeding, 4 animals from each group were intramuscularly inoculated with single dose (3 ml) of Haemorrhagic septiceaemia (Pasteurella multocida P52 strain) oil adjuvant vaccine. The cumulative group mean serum α-tocopherol concentration (µg/100 ml) was 88.12, 210.11, 235.21 and 294.02 in-groups I, II, III and IV, respectively and differed significantly (p<0.001) among the four groups. Lymphocyte stimulation indices (LSI) did not differ among the groups significantly. The pooled mean ELISA antibody titer against Pasteurella multocida (P52 strain) was 788.02, 926.85, 1,214.00 and 1,109.51 for group I, II, III and IV, respectively, which indicated higher antibody titer in groups supplemented with vitamin E as compared to the control group. It may be concluded that vitamin E supplementation increased the α- tocopherol concentration in serum and dietary supplementation of vitamin E at higher level has a humoral immune enhancing effect against killed bacterial antigen. (Asian-Aust. J. Anim. Sci. 2006. Vol 19, No. 4 : 500-506)

最近10年間の東京都芝浦食肉衛生検査所における豚丹毒の摘発状況, 分離菌の血清型および薬剤感受性の特徴

During the period April 1995 to March 2005, 725 (0.027%) of 2, 734, 228 slaughter pigs were diagnosed with swine erysipelas at Shibaura Meat Inspection Center. The rates of detectionin pigs condemned at our Center have trended downwards over the past ten years, suggestinga divergence from the characteristics of official nationwide data. Infections associated with the pigs condemned included urticaria (32 cases), arthritis (356 cases), and endocarditis (six cases). Of the 727Erysipelothrixisolates from these cases, 522 (71.8%), 36 (15.0%) and 127 (17.5%) belonged to serotype 1a, 1b, and serotype 2, respectively. It should be noted that multi-drug resistance to OXA, ERFX, DNFX, DSM, OTC and DOXY (2.4%) could be found in the antimicrobial susceptibility test for the isolates during the period from 2001 to 2003. Moreover, the application of detection of ELISA antibody titer in the joint fluids suggested that ELISA would be useful as screening for the purpose of shortening thereservation periods.-Key

Investigation of recombinant Schistosoma japonicum paramyosin fragments for immunogenicity and vaccine efficacy in mice

Schistosoma japonicum paramyosin, a 97 kDa myofibrillar protein, is a recognized vaccine candidate against schistosomiasis. To improve its expression and to identify protective epitopic regions on paramyosin, the published Chinese Schistosoma japonicum paramyosin cDNA sequence was redesigned using Pichia codon usage and divided into four overlapping fragments (fragments 1, 2, 3, 4) of 747, 651, 669 and 678 bp, respectively. These gene fragments were synthesized and expressed in Pichia pastoris (fragments 2 and 3) or E. coli (fragments 1 and 4). The recombinant proteins were produced at high level and purified using a two-step process involving Ni-NTA affinity chromatography and gel filtration. BALB/c mice were immunized subcutaneously three times at 2-week-intervals with the purified proteins formulated in adjuvant Quil A. The protein fragments were highly immunogenic, inducing high, though variable, ELISA antibody titres, and each was shown to resemble native paramyosin in terms of its recognition by the anti-fragment antibodies in Western blotting. The immunized mice were subjected to cercarial challenge 2 weeks after the final injection and promising protective efficacy in terms of significant reductions in worm burdens, worm-pair numbers and liver eggs in the vaccinated mice resulted. There was no apparent correlation between the antibody titres generated and protective efficacy, as all fragments produced effective but similar levels of protection.

Antibody induction after combined application of an adjuvanted recombinant FeLV vaccine and a multivalent modified live virus vaccine with a chlamydial component

The compatibility, safety and interaction on antibody induction of a combined vaccine application were assessed. Specific pathogen-free cats were vaccinated with either a modified live virus vaccine containing feline calici- (FCV), herpes- (FHV-1), parvovirus (FPV) and Chlamydophila felis ( C. felis), an adjuvanted recombinant feline leukaemia virus (FeLV) vaccine or both vaccines in one syringe. After combined application, FeLV ELISA antibody titres were unaltered, However antibody production based on indirect immunofluorescence assay was remarkably enhanced for FCV and was at selected time points also enhanced for FHV-1 and C. felis but diminished for FPV. The use of these vaccines in combination was safe and will simplify vaccination schedules in veterinary practice.

Correlation of antigenic expression with progress in antibiotic therapy of acute human brucellosis

Human brucellosis is a zoonotic disease which is endemic in Saudi Arabia. The aim of this study was to investigate the humoral immune responses and identify the target antigens that persist at different stages in human brucellosis during antibiotic therapy. To do this, an acute case of accidental nosocomial infection was studied experimentally. Blood was collected from the patient at the time of diagnosis, and at weekly intervals during therapy until remission. IgG and IgM immunoblotting was used to characterize specific antigenic determinants, and ELISA antibody titration was performed to quantify the circulating antibodies. Results indicated that protein bands of 12-13.5 kDa bound IgG in the patient's sera but did not bind IgM on immunoblots and are probably not specific for, or important in, early stage infections. However, an 18 kDa band persisted during infection through remission. The pivotal and most important findings were that the number of protein bands seen on immunoblots, the magnitude of ELISA antibody titres and the concomitant changes in the intensity of the polypeptide bands of 42-43 kDa were positively correlated with the stage of infection. High numbers of anti-IgG and -IgM immunoblot bands coupled with high ELISA antibody titres and a concomitant increase in intensity of the 42-43 kDa bands were positively correlated with acute and severe infection. Conversely, a reduction in the number of polypeptide bands as well as a decrease in the intensity, until the complete disappearance of the 42-43 kDa bands, coupled with low (baseline) ELISA antibody titration values indicated successful treatment and remission. The routine use of the methods described here to ascertain the stage of the disease, assess the progress of antimicrobial therapy and monitor cases of relapse in human brucellosis is suggested.

Serum antibody responses to equine herpesvirus 1 glycoprotein D in horses, pregnant mares and young foals

The envelope glycoprotein D of equine herpesvirus 1 (EHV-1 gD) has been shown in laboratory animal models to elicit protective immune responses against EHV-1 challenge, and hence is a potential vaccine antigen. Here we report that intramuscular inoculation of EHV-1 gD produced by a recombinant baculovirus and formulated with the adjuvant Iscomatrix elicited virus-neutralizing antibody and gD-specific ELISA antibody in the serum of over 90% of adult mixed breed horses. The virus-neutralizing antibody responses to EHV-1 gD were similar to those observed after inoculation with a commercially available killed EHV-1/4 whole virus vaccine. Intramuscular inoculation of EHV-1 gD DNA encoded in a mammalian expression vector was less effective in inducing antibody responses when administered as the sole immunogen, but inoculation with EHV-1 gD DNA followed by recombinant EHV-1 gD induced increased gD ELISA and virus-neutralizing antibody titres in six out of seven horses. However, these titres were not higher than those induced by either EHV-1 gD or the whole virus vaccine. Isotype analysis revealed elevated gD-specific equine IgGa and IgGb relative to IgGc, IgG(T) and IgA in horses inoculated with EHV-1 gD or with the whole virus vaccine. Following inoculation of pregnant mares with EHV-1 gD, their foals had significantly higher levels of colostrally derived anti-gD antibody than foals out of uninoculated mares. The EHV-1 gD preparation did not induce a significant mean antibody response in neonatal foals following inoculation at 12 h post-partum and at 30 days of age, irrespective of the antibody status of the mare. The ability of EHV-1 gD to evoke comparable neutralizing antibody responses in horses to those of a whole virus vaccine confirms EHV-1 gD as a promising candidate for inclusion in subunit vaccines against EHV-1.

Conformational HER-2/neu B-cell Epitope Peptide Vaccine Designed to Incorporate Two Native Disulfide Bonds Enhances Tumor Cell Binding and Antitumor Activities

Cancer vaccines designed to elicit an antibody response that target antigenic sites on a tumor antigen must closely mimic the three-dimensional structure of the corresponding region on the antigen. We have designed a complex immunogen derived from the extracellular domain of human HER-2/neu-(626-649) that represents a three-dimensional epitope. We have successfully introduced two disulfide bonds into this sequence, thereby recapitulating the natural disulfide pairings observed in the native protein. To evaluate the immunogenicity of the doubly cyclized disulfide-linked peptide versus the free uncyclized peptide we examined the induction of antibody responses in both inbred and outbred mice strains, with both constructs eliciting high titered antibodies. The disulfide-paired specific antibodies exhibited enhanced cross-reactivity to HER-2/neu expressed on BT-474 cell line as determined by flow cytometry. The antitumor activities of the disulfidepaired specific antibodies did not improve the in vitro growth inhibition of human breast cancer cells overexpressing HER-2, but showed superior antitumor responses in the context of ADCC and interferon-gamma induction. Inbred mice (FVB/n) vaccinated with the disulfide-paired epitope exhibited a statistically significant reduction in the development of exogenously administered tumors in vivo compared with mice receiving either the free uncyclized or the promiscuous T-cell epitope (MVF) control peptide (p = 0.001). This study demonstrates the feasibility and importance of designing conformational epitopes that mimic the tertiary structure of the native protein for eliciting biologically relevant anti-tumor antibodies. Such approaches are a prerequisite to the design of effective peptide vaccines.

Interleukin-2 potentiates foot-and-mouth disease vaccinal immune responses in mice

The present study describes the role of recombinant human interleukin-2 (rh IL-2) as immunomodulatory molecule in foot-and-mouth disease (FMD) vaccinal immune response in a murine model. The humoral immune response was evaluated by examining the antibody titre against FMD virus type O, A 22 and Asia 1 in serum samples obtained from different groups of mice inoculated with PBS, FMD vaccine alone; vaccine along with rh IL-2 on 0, 7, 14, 21, and 30 days post vaccination (DPV) by indirect double antibody Sandwich ELISA. The cellular immune response was also examined on different DPV by an MTT based lymphoproliferation assay in splenic mononuclear cells (SMNC) obtained from different groups. IL-2 was able to enhance the specific immune response against FMD virus type O, A 22 and Asia 1 as evident by significantly higher ELISA antibody titres ( P < 0.05) in serum obtained from mice receiving IL-2 along with vaccine as compared to mice immunized with vaccine alone. Similarly, the same group of mice showed significantly higher lymphoproliferative responses in SMNC against mitogen PHA and FMD virus types O, A 22 and Asia 1 on all DPVs as compared to the group inoculated with vaccine alone.

Rapid antibody response after vaccination with a virosomal hepatitis a vaccine.

This study was designed to assess the early antibody kinetics after a priming dose, and the extent of the antibody increase after a booster dose of an inactivated virosomal hepatitis A virus (HAV) vaccine (Epaxal). This was an open, uncontrolled study in 30 healthy subjects. The vaccine was injected intramuscularly on day 1 and month 12. Serum antibody titers were measured by ELISA on day 1 (pre dose) and at various time points thereafter until month 12 (pre-booster dose). After the booster dose, antibody titers were measured at various intervals until month 24. Neutralizing antibody titers were measured in 12 subjects a number of times during the 1st month by an antibody neutralization assay. Titers > or = 10 mIU/ml were considered seroprotective. ELISA antibody titers showed a rapid increase post vaccination. By day 15, 96% of subjects were seroprotected, which increased to 100% by day 22 (n = 27 evaluable subjects, aged 18-43 years; 13 male, 14 female). All subjects achieved seroprotective HAV-neutralizing antibody titers by day 11 (n = 12). The booster vaccination at month 12 resulted in a strong response in all subjects, with a sustained anti-HAV antibody titer (1,155 mIU/ml) at month 24. Both the priming and booster doses were well tolerated. Primary vaccination with this virosomal HAV vaccine is well tolerated and induces a rapid HAV-neutralizing antibody response resulting in seroprotection in all subjects within 10 days. In addition, the booster vaccination results in prolonged seroprotective antibody levels.

A New Potent Route of DNA Vaccine Inoculation: DNA-Liposome Complexes on Bare Skin Induce Antigen-Special Antibody Responses

Transcutaneous immunization is a novel strategy for genetic vaccine immunization to induce detectable antigen-special antibody in humor and mucosal. In this study, plasmid expressing hepatitis B surface antigen (pGFP-HBsAg) was encapsulated in liposome, then DNA-liposome complexes were glued on bare skin of mice ear in different dosage (50μg, 10μg and 1μg). As control, DNA-liposome complexes of pGFP-HBsAg and pGFP vector were inoculated intraperitoneally. The anti-HBsAg antibodies of serum were detected weekly by ELISA. It was found that the detectable antibodies of transcutaneous immunized mouse were elicited after four weeks, and reached a maximum at the sixth week. Even 1μg plasmid DNA in liposomes through immune skin can elicit the highest ELISA antibody titer (> 1:512) in test group, and corresponding percentage of positive response is up to 71% at sixth week, but higher amounts of plasmid DNA (50μg DNA per mice) on immune skin cannot induce higher antibody levels. The result showed that DNA-liposome complexes glued on bare skin appear to be a novel method for the administration of DNA vaccines.