Defined tuberculosis vaccine, Mtb72F/AS02A, evidence of protection in cynomolgus monkeys.

The development of a vaccine for tuberculosis requires a combination of antigens and adjuvants capable of inducing appropriate and long-lasting T cell immunity. We evaluated Mtb72F formulated in AS02A in the cynomolgus monkey model. The vaccine was immunogenic and caused no adverse reactions. When monkeys were immunized with bacillus Calmette-Guérin (BCG) and then boosted with Mtb72F in AS02A, protection superior to that afforded by using BCG alone was achieved, as measured by clinical parameters, pathology, and survival. We observed long-term survival and evidence of reversal of disease progression in monkeys immunized with the prime-boost regimen. Antigen-specific responses from protected monkeys receiving BCG and Mtb72F/AS02A had a distinctive cytokine profile characterized by an increased ratio between 3 Th1 cytokines, IFN-gamma, TNF, and IL-2 and an innate cytokine, IL-6. To our knowledge, this is an initial report of a vaccine capable of inducing long-term protection against tuberculosis in a nonhuman primate model, as determined by protection against severe disease and death, and by other clinical and histopathological parameters.

Pneumococcal capsular polysaccharides conjugated to protein D for prevention of acute otitis media caused by both Streptococcus pneumoniae and non-typable Haemophilus influenzae: a randomised double-blind efficacy study.

BACKGROUND: Acute otitis media is one of the most commonly-diagnosed childhood infections. This study assessed the efficacy of a novel vaccine that contained polysaccharides from 11 different Streptococcus pneumoniae serotypes each conjugated to Haemophilus influenzae-derived protein D in prevention of acute otitis media. METHODS: 4968 infants were randomly assigned to receive either pneumococcal protein D conjugate or hepatitis A vaccine at the ages of 3, 4, 5, and 12-15 months and were followed-up until the end of the second year of life. Middle-ear fluid was obtained for bacteriological culture and serotyping in children who presented with abnormal tympanic membrane or presence of middle-ear effusion, plus two predefined clinical symptoms. The primary endpoint was protective efficacy against the first episode of acute otitis media caused by vaccine pneumococcal serotypes. Analysis was per protocol. FINDINGS: From 2 weeks after the third dose to 24-27 months of age, 333 clinical episodes of acute otitis media were recorded in the protein D conjugate group (n=2455) and 499 in the control group (n=2452), giving a significant (33.6% [95% CI 20.8-44.3]) reduction in the overall incidence of acute otitis media. Vaccine efficacy was shown for episodes of acute otitis media caused by pneumococcal vaccine serotypes (52.6% [35.0-65.5] for the first episode and 57.6% [41.4-69.3] for any episode). Efficacy was also shown against episodes of acute otitis media caused by non-typable H influenzae (35.3% [1.8-57.4]). The vaccine reduced frequency of infection from vaccine-related cross-reactive pneumococcal serotypes by 65.5%, but did not significantly change the number of episodes caused by other non-vaccine serotypes. INTERPRETATION: These results confirm that using the H influenzae-derived protein D as a carrier protein for pneumococcal polysaccharides not only allowed protection against pneumococcal otitis, but also against acute otitis media due to non-typable H influenzae. Whether this approach would also allow improved protection against lower respiratory tract infections warrants further investigation.

An evaluation of dengue type-2 inactivated, recombinant subunit, and live-attenuated vaccine candidates in the rhesus macaque model.

The safety, immunogenicity, and protective efficacy of two non-replicating antigen-based vaccines and one live-attenuated virus (LAV) vaccine for dengue type-2 (dengue-2) virus were evaluated in the rhesus macaque model. The non-replicating vaccines consisted of whole, purified inactivated virus (PIV) and a recombinant subunit protein containing the amino-(N)-terminal 80% of envelope protein (r80E), each formulated with one of five different adjuvants. Each formulation was administered to three animals on a 0, 3-month schedule. Following the primary immunizations, 37 of 39 animals demonstrated dengue-2 virus neutralizing antibodies. After the booster immunizations all animals had dengue neutralizing antibodies with peak titers ranging from 1:100 to 1:9700. The highest neutralizing antibody titers were observed in the groups that received r80E antigen formulated with AS04, AS05, or AS08 adjuvant, and PIV formulated with AS05 or AS08 adjuvant. These newer adjuvants are based on alum, fraction QS-21 of saponin, and monophosphoryl lipid A (MPL). Protection was evaluated by dengue-2 virus challenge 2 months after the booster by the measurement of circulating virus (viremia) and post-challenge immune responses. Several groups exhibited nearly complete protection against viremia by bioassay, although there was evidence for challenge virus replication by Taqmantrade mark and immunological assays. None of the vaccines conferred sterile immunity.

Pre-clinical immunogenicity and efficacy trial of a recombinant hepatitis E vaccine.

We have demonstrated that recombinant hepatitis E vaccine suitable for clinical evaluation was highly immunogenic and efficacious in preventing hepatitis E and even infection in rhesus macaques following intravenous challenge with three different genotypes of hepatitis E virus (HEV). Two doses of vaccine were essential for optimal protection; the two-dose regimen was more important than the formulation of the vaccine for achieving efficacy. The titers of anti-HEV that were protective in this study were quantified against a World Health Organization (WHO) standard. This permits direct comparison of the results with other studies. The results of this pre-clinical trial of a candidate hepatitis E vaccine strongly suggest that it will be highly efficacious for preventing hepatitis E in the field trial of this vaccine that is currently in progress in Nepal.