Comparative efficacy of an indigenous 'inactivated vaccine' using highly pathogenic field strain of Mycobacterium avium subspecies paratuberculosis 'Bison type' with a commercial vaccine for the control of Capri-paratuberculosis in India

Johne's disease (JD) is endemic in goatherds located at Central Institute for Research on Goats, Makhdoom, since 1979 and lately it has been reported from farmer's herds in equal frequencies. Despite using test and slaughter method for the control of JD for more than 25 years in these herds, incidence of JD has not been reduced. Efficacy of 'indigenous vaccine' containing native 'Bison type' genotype of Mycobacterium avium subspecies paratuberculosis (MAP) was compared with commercial vaccine using challenge studies with homologous strain of MAP. Goat kids (85) were randomly divided in to three groups. Kids were vaccinated with 1 ml of vaccine subcutaneously and Sham-immunized with 1 ml of sterile PBS. All kids except 3 in each group were challenged twice at 75- and 275-day post-vaccination (DPV). Four goats each from three groups were sacrificed at 200-day post-challenge to evaluate carcass and histopathologically for vaccine and challenge response in kids of different groups. Samples (blood, serum and fecal) were screened for LTT, ELISA and shedding of bacilli and data on live animal traits, mortality and experimental sacrifice were compared. Average body weights gained by goats in three groups at different stages of trials (0, 1-75, 76-275, 276-425 DPV) showed marked improvements in performance of vaccinated groups over 'Sham-immunized' group. Effect of vaccines against challenge became visible in terms of body weights gained at 276-425 DPV ('Bison' group gained significantly higher body weights than 'Sham-immunized'). Mortality was significantly less in two vaccinated as compared to 'Sham-immunized'. Vaccinated groups also had significant stimulation and sero-conversion for cell mediated and humoral immune response, respectively as compared to 'Sham-immunized'. Results of post-challenged fecal culture showed significant reduction in shedding of MAP in both vaccinated groups than in 'Sham-immunized'. There was significant improvement in external and internal body traits and histological lesions in case of vaccinated than 'Sham-immunized' group.     

Effect of cationic liposomes on BCG trafficking and vaccine-induced immune responses following a subcutaneous immunization in mice

While formulating Mycobacterium bovis BCG in lipid-based adjuvants has been shown to increase the vaccine's protective immunity, the biological mechanisms responsible for the enhanced potency of lipid encapsulated BCG are unknown. To assess whether mixing BCG in adjuvant increases its immunogenicity by altering post-vaccination organ distribution and persistence, mice were immunized subcutaneously with conventional BCG Pasteur or BCG formulated in DDA/TDB adjuvant and the bio-distribution of BCG bacilli was evaluated in mouse lungs, spleens, lymph nodes, and livers for up to 1 year. Although BCG was rarely detected in mouse livers, mycobacteria were found in mouse lungs, spleens, and lymph nodes for at least 1 year post-vaccination. However, at various time points during the 1 year study, the frequency of lung and spleen infections and the number of mycobacteria in infected organs of individual mice were highly variable. In contrast, mycobacteria were nearly always detected in the lymph nodes of vaccinated mice. While the frequency and extent of lymph node infections generally were not significantly different between mice vaccinated with adjuvanted or nonadjuvanted BCG preparations, multiparameter flow cytometry analysis of lymph node cells showed significantly higher frequencies of CD4+ and CD8+ T cells expressing IFN-γ and IFN-γ/TNF-α in mice immunized with adjuvanted BCG. Overall, our data suggest that the relationship between lymph node infection and the generation of anti-tuberculosis protective responses following BCG vaccination should be further investigated.     

Safety and efficacy of Rift Valley fever Smithburn and Clone 13 vaccines in calves

Two modified live attenuated vaccines against the disease Rift Valley fever (RVF) have been tested for safety and efficacy in young calves. The RVF Smithburn vaccine produced in South Africa and used successfully to prevent and control the disease in endemic sub-Saharan countries was compared to the candidate vaccine RVF Clone 13. Five sero-negative calves per vaccine group were vaccinated with a single dose of each vaccine and tested for antibody response. All vaccinated calves were challenged with a highly virulent RVF virus together with five unvaccinated calves used as control of the challenge. Protection was confirmed in all vaccinated animals as they did not show any clinical signs typical of RVF. A good neutralizing antibody response was induced post-vaccination and no viraemia could be detected post-challenge in calves of both vaccine groups. All non-vaccinated control animals showed clinical symptoms of RVF, high viraemia and were euthanized. This study reported the first case of blindness in cattle resulting from virulent RVF virus infection in unvaccinated calves used as negative controls.     

Ag85B-ESAT-6 adjuvanted with IC31® promotes strong and long-lived Mycobacterium tuberculosis specific T cell responses in volunteers with previous BCG vaccination or tuberculosis infection

New TB vaccines are urgently needed because of the apparent lack of effect of the BCG vaccine on rates of adult contagious pulmonary tuberculosis and the risk of disseminated BCG disease in immunocompromised individuals. Since BCG appears to protect children, the primary target for vaccine development is a booster vaccine for adults but such vaccines ideally need to be able to efficiently prime mycobacterially naïve individuals as well as boost individuals previously vaccinated with BCG and those latently infected with TB. Protective immunity against Mycobacterium tuberculosis depends mainly on the generation of a Th1-type cellular immune response characterized by interferon-gamma (IFN-γ) production. In the present study, we monitored safety and IFN-γ responses in healthy BCG-vaccinated and prior or latently TB-infected individuals receiving a novel vaccine composed of the fusion protein Ag85B-ESAT-6 combined with the adjuvant IC31^®, administered at 0 and 2 months. Vaccination caused few local or systemic adverse effects besides transient soreness at the injection site, but it elicited strong antigen-specific T cell responses against Ag85B-ESAT-6 and both the Ag85B and ESAT-6 components, that could be augmented by second vaccination. The strong responses persisted through 32 weeks of follow-up, indicating the induction of a persistent memory response in the vaccine recipients.     

Ag85B–ESAT-6 adjuvanted with IC31 promotes strong and long-lived Mycobacterium tuberculosis specific T cell responses in naïve human volunteers

Though widely used, the BCG vaccine has had little apparent effect on rates of adult pulmonary tuberculosis. Moreover, the risk of disseminated BCG disease in immunocompromised individuals means that improved TB vaccines ideally need to be able to efficiently prime mycobacterially-naïve individuals as well as boost individuals previously vaccinated with BCG. Protective immunity against Mycobacterium tuberculosis is thought to depend on the generation of a Th1-type cellular immune response characterized by interferon-gamma (IFN-γ) production. In the present study, we monitored safety and IFN-γ responses in healthy TB-naïve humans receiving an entirely novel vaccine, composed of the fusion protein Ag85B–ESAT-6, administered at 0 and 2 months either as recombinant protein alone or combined with two concentrations of the novel adjuvant IC31^®. Vaccination did not cause local or systemic adverse effects besides transient soreness at the injection site, but it elicited strong antigen-specific T cell responses against H1 and both the Ag85B and the ESAT-6 components. These strong responses persisted through 2.5 years of follow-up, indicating the induction of a substantial memory response in the vaccine recipients.     

Evaluating the sensitivity of the bovine BCG challenge model using a prime boost Ad85A vaccine regimen

In the absence of biomarkers of protective immunity, newly developed vaccines against bovine tuberculosis need to be evaluated in virulent Mycobacterium bovis challenge experiments, which require the use of expensive and highly in demand Biological Safety Level 3 (BSL3) animal facilities. The recently developed bovine BCG challenge model offers a cheaper and faster way to test new vaccine candidates and additionally reduces the severity of the challenge compared to virulent M. bovis challenge in line with the remits of the NC3Rs. In this work we sought to establish the sensitivity of the BCG challenge model by testing a prime boost vaccine regimen that previously increased protection over BCG alone against M. bovis challenge. All animals, except the control group, were vaccinated subcutaneously with BCG Danish, and half of those were then boosted with a recombinant adenoviral vector expressing Antigen 85A, Ad85A. All animals were challenged with BCG Tokyo into the prescapular lymph node and the bacterial load within the lymph nodes was established. All vaccinated animals, independent of the vaccination regimen, cleared BCG significantly faster from the lymph node than control animals, suggesting a protective effect. There was however, no difference between the BCG and the BCG-Ad85A regimens. Additionally, we analysed humoral and cellular immune responses taken prior to challenge for possible predictors of protection. Cultured ELISpot identified significantly higher IFN-ɣ responses in protected vaccinated animals, relative to controls, but not in unprotected vaccinated animals. Furthermore, a trend for protected animals to produce more IFN-ɣ by quantitative PCR and intracellular staining was observed. Thus, this model can also be an attractive alternative to M. bovis challenge models for the discovery of protective biomarkers.     

Reduced tissue colonization of Mycobacterium avium subsp. paratuberculosis in neonatal calves vaccinated with a cocktail of recombinant proteins

An increasing prevalence of paratuberculosis supports the need for new efficacious vaccines as an essential management tool. Two separate studies were performed in neonatal calves to evaluate the effectiveness of pooled recombinant Mycobacterium avium subsp. paratuberculosis (MAP) proteins (MAP1087, MAP1204, MAP1272c, MAP2077c) as a potential vaccine. In the first study vaccinated calves were immunized with 400 µg protein cocktail per dose, whereas the second study compared doses of 400 µg and 800 µg of protein cocktail, followed by challenge with live MAP for both vaccinated and nonvaccinated control calves 28 days post-vaccination. At the end of 12 months, tissue colonization with MAP was significantly reduced for the vaccinated calves compared to control animals. A higher dose of vaccine improved protection, with further reductions of MAP burden. Antigen-specific IFN-γ responses and serum antibody responses were similar regardless of vaccination, indicating exposure to MAP invoked conventional host immune responses. Host immunity differed due to vaccination, resulting in increased percentages of CD4+ T cells and B cells after stimulation of PBMCs with antigen. Interestingly, gene expression in PBMCs was similar for both control and vaccinated calves except for significant increases in IFN-γ, IL-12, and IL-17 expression observed in vaccinated calves. Vaccination with a cocktail of immunogenic recombinant MAP proteins was efficacious in reducing the level of infection and fecal shedding of neonatal calves and may be a potential tool for curtailing the spread of Johne’s disease.     

Protection of kids against Cryptosporidium parvum infection after immunization of dams with CP15-DNA.

In this study the effectiveness of a DNA vaccine to confer protection against cryptosporidiosis, an enteric infection of lifestock and humans, was evaluated. A vaccination protocol using a recombinant plasmid encoding the 15 kDa surface sporozoite protein of Cryptosporidium parvum was developed in adult pregnant goats. The present study reports that nasal immunization of pregnant goats with CP15-DNA led to a transfer of immunity to offspring conferring protection against C. parvum infection. Kids from CP15-DNA-vaccinated dams shed significantly fewer oocysts and over a shorter period than did kids from unvaccinated goats. The low level of parasite development in protected kids did not affect their growth whereas unprotected kids grew much slowly. There was still a significant difference in the weights of protected and unprotected kids after complete recovery. Anti-CP15 antibodies were present in serum and colostrum from vaccinated goats. Nevertheless, the precise immune mechanism of protection has still to be determined. This vaccine should reduce the economic losses due to cryptosporidiosis in ruminants, specially in small ruminants (calves, lambs, kids). It has also the potential to reduce environmental contamination by reducing oocyst shedding.     

Safety,immunogenicity and shedding of LAIV4 in HIV-infected and uninfected children

ObjectivesHIV-infected children have poor responses to inactivated influenza vaccines. Live vaccines (LAIVs) are highly efficacious in children, but they are not used in HIV-infected children du e to limited information. We investigated the safety, immunogenicity and viral shedding of LAIV4 in HIV-infected compared with uninfected children.DesignForty-six HIV-infected and 56 uninfected children 2 to 25 years old, who had been previously vaccinated against influenza, consented to receive a single dose of LAIV4. All grade adverse events (AEs) were recorded in the first month post-vaccination and serious AEs (SAEs) throughout the influenza season. Nasopharyngeal swabs for influenza PCR and IgA ELISA and blood for hemagglutination inhibition antibody (HAI) measurements were collected at entry, 2–5, 7–10 and 21–28 days post-vaccination.ResultsThe HIV-infected subjects had median CD4+ cells of 649 cells/μL and plasma HIV RNA of 20 copies/mL. AEs were similar in the two groups. There were no vaccine-related SAEs. Shedding of ≥1 vaccine virus was detected in 67% HIV-infected and 50% uninfected participants (p = 0.14). HAI titers did not appreciably change, but mucosal IgA antibodies significantly increased post-vaccination in both groups. High baseline HAI and IgA antibody concentrations were associated with decreased viral shedding in controls, but not in HIV-infected subjects. Similar proportions of HIV-infected vaccinees and controls reported influenza-like illnesses (12% and 6%) throughout the season.ConclusionsLAIV4 was equally safe and immunogenic and caused similar viral shedding in HIV-infected and uninfected children. A correlate of protection against vaccine viral shedding was not identified in HIV-infected participants, although both circulating and mucosal antibodies correlated with protection in controls.     

Evaluation of immune responses and protective efficacy in a goat model following immunization with a coctail of recombinant antigens and a polyprotein of Mycobacterium avium subsp. paratuberculosis

The protective efficacy of four recombinant antigens (85A, 85B, superoxide dismutase [SOD], and a fusion polypeptide [Map74F]) of Mycobacterium avium subsp. paratuberculosis (MAP) along with the adjuvant dimethydioctadecyl ammonium bromide (DDA) was assessed in a goat challenge model. Animals were immunized with the four antigens with adjuvant DDA (Group I, eight goat kids) or without the adjuvant (Group II, eight goat kids) or adjuvant only (Group III, nine goat kids). Animals were boostered 3 weeks after the primary vaccination and challenged 3 weeks after the booster. Significant antigen-specific lymphoproliferation was observed in the immunized animals 3 weeks after the booster immunization. This response increased further at 4 weeks after the booster. Similarly, antigen-specific IFN-gamma responses increased in the immunized animals 3 weeks after the booster. The response was significantly higher for 85A and Map74F at 10 weeks after primary vaccination (APV) in Group I animals compared to the other two groups. CD4+ T-cell populations were higher in the vaccinated animals from 6 to 10 weeks APV than those of the control animals. A significant increase in recombinant antigen-specific IFN-gamma gene expression was detected in the vaccinated animals. At necropsy (38 weeks APV), our multicomponent subunit vaccine imparted a significant protection in terms of reduction of MAP burden in target organs as compared to sham-immunized goats. This study indicates that our multicomponent subunit vaccine induced a good Th1 response and conferred protection against MAP infection in a goat challenge model.     

EXPERIMENTAL studies of vaccination,allergy, and immunity in tuberculosis. II. Effect of varying the dose of BCG

Results are given for one of a series of projects designed to investigate the relation between observable post-vaccination responses and acquired resistance to tuberculosis. Controlled variations in the dose of BCG vaccine have previously been shown to cause systematic variations in the degree of skin sensitivity to tuberculin and the size of vaccinal lesions in human beings: the purpose of the present project was to see if similar variations would be produced in guinea-pigs and then, by infecting the animals with virulent tubercle bacilli, to see how survival time correlates with tuberculin allergy and vaccinal lesions.Four doses of freshly prepared BCG vaccine, ranging from 1/100 to 10 times the dose ordinarily used for intradermal vaccination of humans, and one dose of heat-killed BCG 100 times that strength, were used to vaccinate five groups of guinea-pigs, each containing 120 animals. A sixth group of 120 animals was not vaccinated. All animals were tuberculin-tested just before and five weeks after vaccination, challenged with a strong dose of H-37 Rv, and then allowed to die, so that survival time could be used as a measure of resistance.As the dose of living BCG was increased, groups of guinea-pigs showed a progressive increase in the average degree of post-vaccination tuberculin allergy, size of vaccinal lesion, and length of survival after virulent infection. The heat-killed BCG resulted in weak allergy and a short survival time, yet the vaccinal lesions averaged about as large as would be expected from a corresponding dose of living BCG. These results (excluding studies of survival time) correspond closely to those found in human studies.The implications of the results with respect to practical BCG vaccination programmes, while no more than speculative at present, point toward possible advantages in inducing high degrees of tuberculin allergy and toward the dubious significance of the vaccinal lesion as an index of a vaccine's immunizing potency.     

Evaluation of cell-mediated immune responses to two BCG vaccination regimes in young children in South Korea

Children in South Korea are vaccinated with either BCG Pasteur vaccine intradermally (ID), or with BCG Tokyo vaccine given by multipuncture device (MP). Data from a recent national survey indicated that in children under 6 years old, 31.1% had received the ID vaccine and 64.5% the MP vaccine. To compare the T cell responses induced by the two vaccines, children aged 3-7 were recruited and tested for tuberculin skin test reactivity and for in vitro IFN-γ responses to mycobacterial antigens. DTH responses were not significantly different in children vaccinated by either the ID or MP vaccines. PPD-induced IFN-γ was measured in supernatants of 6-day diluted whole blood cultures. IFN-γ production to PPD was not significantly different in the two vaccine groups, although there is a trend that the MP group gives a higher proportion of IFN-γ positivity than the ID group. In addition, when IFN-γ responses to the antigens ESAT-6 and CFP-10 were assessed in the 6-7 year old group, there was no significant difference between the two vaccine groups. Thus, there was no evidence that the increasing use of MP vaccination has reduced protection against M. tuberculosis in young children in South Korea, based on immunogenicity as assessed by DTH and IFN-γ responses to PPD, and also equivalent frequency of responses to ESAT-6 and CFP-10.     

Lack of correlation between BCG-induced tuberculin skin test sensitisation and protective immunity in cattle

Vaccination of cattle with Mycobacterium bovis Bacille Calmette-Guérin (BCG) can provide significant protection against bovine tuberculosis (TB). However, BCG vaccination sensitises animals to respond to the tuberculin skin-test. This provides a potential operational impediment to the use of BCG as a cattle vaccine since the tuberculin skin-test is the primary surveillance tool used by many countries with ‘test and slaughter’ control strategies. Currently, it is also unclear what BCG-induced skin-test conversion means in respects to BCG's protective immunity. In the current study we first investigated the duration of tuberculin skin-test sensitisation in calves neonatally vaccinated with BCG. BCG vaccination induced strong skin-test responses in calves during their first 6 months. However, a rapid decay in skin-test sensitivity was observed after this time. Between 6 and 9 months this represented a reduction from 80% to 8% of calves providing a positive response in the single intradermal comparative cervical tuberculin test at standard interpretation. We next investigated the relationship between BCG induced skin-test sensitivity and retention of protective immunity. Calves were neonatally vaccinated with BCG and subsequently divided into 2 groups based on retention or loss of tuberculin skin-test responses after 6 months. In contrast to their skin-test responsiveness, these vaccinates maintained their tuberculin specific IFN-γ blood responses. Moreover, irrespective of their pre-challenge skin-test responses, following M. bovis challenge both groups of BCG vaccinated calves demonstrated comparable levels of protection, as evidenced by reduced TB-associated pathology. Therefore, we have demonstrated that following neonatal BCG vaccination of cattle, tuberculin skin-test responder frequencies waned rapidly after 6 months but importantly, loss of skin-test sensitivity did not correlate with loss of protective immunity. These findings could have implications for the practical application of BCG based cattle vaccines.     

Kinetics of antiviral CD8 T cell responses during primary and post-vaccination secondary bovine respiratory syncytial virus infection

We have measured antiviral CD8 T cells responses in bovine respiratory syncytial virus (bRSV) infected calves that had been immunized with either formalin-inactivated (FI) or live-attenuated (L) bRSV, with evidence of immunopathology following challenge of calves vaccinated with FI-bRSV. In all cases, bRSV infection induced potent pulmonary CD8 T cell responses. The kinetics of the post-challenge response in L-bRSV immunized animals was accelerated compared to the FI-bRSV and PBS groups, suggesting that only the L-bRSV vaccine, and not the FI-bRSV vaccine, had primed memory T cells. The differences between primary and post-vaccination secondary infection were very minor, in terms of the proliferation status of pulmonary CD8 T cells. Functional IFN-gamma+ CD8 responses were slightly higher in the FI-bRSV vaccinated animals. Furthermore, the existence of strong IFN-gamma+ CD8 responses in FI-bRSV vaccinated animals after challenge suggests (i) that these IFN-gamma+ responses in FI-bRSV immunized animals do not protect against immunopathology, and (ii) that Th-2 biased responses during bRSV challenge after vaccination with FI-bRSV have a limited impact on the CD8 responses in the bronchoalveolar lavage fluid. Thus, several response patterns (Th-l/Th-2) seem to co-exist during bRSV infection.     

Detection of fecal shedding of rotavirus vaccine in infants following their first dose of pentavalent rotavirus vaccine

Studies on rotavirus vaccine shedding and its potential transmission within households including immunocompromised individuals are needed to better define the potential risks and benefits of vaccination. We examined fecal shedding of pentavalent rotavirus vaccine (RV5) for 9 days following the first dose of vaccine in infants between 6 and 12 weeks of age. Rotavirus antigen was detected by enzyme immunoassay (EIA), and vaccine-type rotavirus was identified by nucleotide sequencing based on genetic relatedness to the RV5 VP6 gene. Stool from 22 (21.4%) of 103 children contained rotavirus antigen-positive specimens on ≥1 post-vaccination days. Rotavirus antigen was detected as early as post-vaccination day 3 and as late as day 9, with peak numbers of shedding on post-vaccination days 6 through 8. Vaccine-type rotavirus was detected in all 50 antigen-positive specimens and 8 of 8 antigen-negative specimens. Nine (75%) of 12 EIA-positive and 1 EIA-negative samples tested culture-positive for vaccine-type rotavirus. Fecal shedding of rotavirus vaccine virus after the first dose of RV5 occurred over a wide range of post-vaccination days not previously studied. These findings will help better define the potential for horizontal transmission of vaccine virus among immunocompromised household contacts of vaccinated infants for future studies.     

Immunogenicity of a modified-live virus vaccine against bovine viral diarrhea virus types 1 and 2, infectious bovine rhinotracheitis virus,bovine parainfluenza-3 virus,and bovine respiratory syncytial virus when administered intranasally in young calves

The immunogenicity of an intranasally-administered modified-live virus (MLV) vaccine in 3–8 day old calves was evaluated against bovine viral diarrhea virus (BVDV) types 1 and 2, infectious bovine rhinotracheitis (IBR) virus, parainfluenza-3 (PI-3) virus and bovine respiratory syncytial virus (BRSV). Calves were intranasally vaccinated with a single dose of a multivalent MLV vaccine and were challenged with one of the respective viruses three to four weeks post-vaccination in five separate studies. There was significant sparing of diseases in calves intranasally vaccinated with the MLV vaccine, as indicated by significantly fewer clinical signs, lower rectal temperatures, reduced viral shedding, greater white blood cell and platelet counts, and less severe pulmonary lesions than control animals. This was the first MLV combination vaccine to demonstrate efficacy against BVDV types 1 and 2, IBR, PI-3 and BRSV in calves 3–8 days of age.     

Characterisation of vaccine-induced, broadly cross-reactive IFN-γ secreting T cell responses that correlate with rapid protection against classical swine fever virus

Live attenuated C-strain classical swine fever viruses (CSFV) provide a rapid onset of protection, but the lack of a serological test that can differentiate vaccinated from infected animals limits their application in CSF outbreaks. Since immunity may precede antibody responses, we examined the kinetics and specificity of peripheral blood T cell responses from pigs vaccinated with a C-strain vaccine and challenged after five days with a genotypically divergent CSFV isolate. Vaccinated animals displayed virus-specific IFN-γ responses from day 3 post-challenge, whereas, unvaccinated challenge control animals failed to mount a detectable response. Both CD4(+) and cytotoxic CD8(+) T cells were identified as the cellular source of IFN-γ. IFN-γ responses showed extensive cross-reactivity when T cells were stimulated with CSFV isolates spanning the major genotypes. To determine the specificity of these responses, T cells were stimulated with recombinant CSFV proteins and a proteome-wide peptide library from a related virus, BVDV. Major cross-reactive peptides were mapped on the E2 and NS3 proteins. Finally, IFN-γ was shown to exert potent antiviral effects on CSFV in vitro. These data support the involvement of broadly cross-reactive T cell IFN-γ responses in the rapid protection conferred by the C-strain vaccine and this information should aid the development of the next generation of CSFV vaccines.     

BCG sub-strains induce variable protection against virulent pulmonary Mycobacterium tuberculosis infection, with the capacity to drive Th2 immunity

The hallmark of a vaccine is to induce long-term protective immunity against the pathogen. The use of Mycobacterium bovis BCG as a vaccine against tuberculosis has been problematic in that immunity induced by BCG wanes over time and it may be less effective against more virulent strains of Mycobacterium tuberculosis. Thus it is important to determine what factors might be associated with waning or inefficient immunity. One such factor has been associated with the difference in many types of BCG that are used around the world, or more specifically due to the loss of genomic material in the various sub-strains used in vaccination programs. To address this issue we investigated the long-term immune response generated by 3 sub-strains BCG in the C57BL/6 mouse model of experimental tuberculosis. Mice vaccinated with these diverse strains of BCG were assessed at 6 and 12 months post-vaccination. All BCG sub-strain induced elevated levels of IFN-γ-producing cells at each time point as determined by ELISpot assay. However, when mice were challenged at 6 and 12 months with either M. tuberculosis H37Rv or HN878 the ability of the BCG sub-strains to protect vaccinated mice varied, depending on the time of challenge and on the strain used to infect mice. BCG Pasteur was then used to vaccinate guinea pigs, which were subsequently infected with either H37Rv or HN878. Data showed that BCG Pasteur prolonged the survival of guinea pigs against infection with both strains. Taken together these data suggest that longevity of the immune response generated by BCG is not related to the loss of genetic material and that BCG can induce a protective immune response to infection with a clinical strain of M. tuberculosis.     

Safety and immunogenicity of three lots of meningococcal serogroup C conjugate vaccine administered at 2, 3 and 4 months of age

The reactogenicity and immunogenicity of meningococcal serogroup C conjugate (MenC) vaccine was assessed in 322 infants vaccinated at 2, 3, and 4 months of age, with concomitant administration of mixed diphtheria-tetanus-whole-cell pertussis vaccine and Haemophilus influenzae type b conjugate vaccine (DTwP-Hib) and oral polio vaccine. All infants in whom post-vaccination meningococcal C anticapsular IgG levels were assayed (n = 265) attained > or = 2 microg ml(-1). Serum bactericidal titres were assayed for a proportion of subjects (n = 171), 98% of whom obtained a reciprocal titres > or = 8. Local reactions were less frequent at the MenC injection site than at the DTP-Hib site. Systemic events were frequent, but consistent with established DTwP-Hib experience. The study demonstrates that MenC vaccine is immunogenic and well tolerated in infants at manufacturing scale production levels.     

Epitope based recombinant BCG vaccine elicits specific Th1 polarized immune responses in BALB/c mice

Developing an efficacious vaccine is one of the highest priorities in tuberculosis research. A vaccine based on T cell epitopes representing multiple antigens is an ideal approach to generate effective cellular immunity against the disease. In the present study, we have selected four T cell epitopes from four well defined Mycobacterium tuberculosis antigens, Ag85C (Rv2903c), 10-kDa culture filtrate protein (CFP-10) (Rv3874), PPE68 (Rv3873) and INV (Rv1478). The epitope encoding genes were grafted into a Cpn 10 based epitope delivery system. The cpn 10-epitope chimeras were further cloned and expressed in BCG to obtain four rBCGs (BCG::CFP, BCG::FBP, BCG::PPE and BCG::INV). Both cellular and humoral immune responses induced by these r-BCG strains were evaluated in BALB/c mice after subcutaneous injection of a single dose of 1×10(6)CFU of the individual rBCGs. Compared to the parent BCG immunized animals the splenocytes derived from rBCG vaccinated groups showed greater antigen specific proliferation, characterized with higher IFN-γ response and reduced IL-4 secretion. Also rBCG vaccination was able to induce specific humoral immune response with an enhanced IgG2a/IgG1 ratio. The rBCGs therefore favor an epitope specific Th1 type response, which is known to be important for mycobacterial immunity. Further when two of the rBCGs (BCG::CFP and BCG::FBP) were tested for their protective efficacy both the rBCGs were comparable to BCG in a H37Rv challenge study performed in guinea pigs.