Mosaic Bovine Viral Diarrhea Virus Antigens Elicit Cross-Protective Immunity in Calves.

Bovine Viral Diarrhea Virus (BVDV) is an important pathogen that plays a significant role in initiating Bovine Respiratory Disease Complex (BRDC) in cattle. The disease causes multi-billion dollar losses globally due to high calf mortality and increased morbidity leading to heavy use of antibiotics. Current commercial vaccines provide limited cross-protection with several drawbacks such as safety, immunosuppression, potential reversion to virulence, and induction of neonatal pancytopenia. This study evaluates two prototype vaccines containing multiple rationally designed recombinant mosaic BVDV antigens for their potential to confer cross-protection against diverse BVDV strains. Genes encoding three novel mosaic antigens, designated E2123, NS2-31, and NS2-32, were designed in silico and expressed in mammalian cells for the formulation of a prototype protein-based vaccine. The mosaic antigens contain highly conserved protective epitopes from BVDV-1a, -1b, and -2, and included unique neutralizing epitopes from disparate strains to broaden coverage. We tested immunogenicity and protective efficacy of Expi293TM-expressed mosaic antigens (293F-E2123, 293F-NS2-31, and 293F-NS2-32), and baculovirus-expressed E2123 (Bac-E2123) mosaic antigen in calves. The Expi293TM-expressed antigen cocktail induced robust BVDV-specific cross-reactive IFN-γ responses, broadly neutralizing antibodies, and following challenge with a BVDV-1b strain, the calves had significantly (p < 0.05) reduced viremia and clinical BVD disease compared to the calves vaccinated with a commercial killed vaccine. The Bac-E2123 antigen was not as effective as the Expi293TM-expressed antigen cocktail, but it protected calves from BVD disease better than the commercial killed vaccine. The findings support feasibility for development of a broadly protective subunit BVDV vaccine for safe and effective management of BRD.

Enhanced protective efficacy of Borrelia burgdorferi BB0172 derived-peptide based vaccine to control Lyme disease.

Lyme disease (LD) accounts for over 70% of tick-borne disease reported in the United States. The disease in humans is characterized by skin rash, arthritis, cardiac and neurological signs. Vaccination is the most efficient preventive measure that could be taken to reduce the incidence of the LD worldwide; however, at present no vaccine is available. In this study, evaluation of the Borrelia burgdorferi BB0172-derived peptide (PepB) in conjugated formulations was investigated as a vaccine candidate in murine model of LD. In brief, PepB was conjugated to the Cross-Reacting Material 197 (CRM197) and to Tetanus Toxoid heavy chain (TTHc) molecules, and subsequently used to immunize C3H/HeN mice. Following the challenge with 105 spirochetes/mouse via subcutaneous inoculation, TTHc:PepB construct showed protection in 66% of the immunized animals. Hence, to further evaluate the efficacy of TTHc:PepB, immunized mice were challenged with B. burgdorferi using the tick model of infection. The outcome of this experiment revealed that serum from TTHc:PepB immunized mice was borrelicidal. After tick infection, bacterial burden was significantly reduced (over 70%) in vaccinated animals when compared with the control groups regardless of whether the mice were infested 8 or 12-weeks post-priming. Therefore, we conclude that PepB conjugated antigens can serve as an alternative to prevent LD; nevertheless, further studies will be needed to dissect the mechanisms by which anti-PepB IgG antibodies are able to kill B. burgdorferi in vitro and in vivo to further advance in the development of formulations and delivery alternative to generate a safe anti-LD vaccine.

Adenovirus-vectored novel African Swine Fever Virus antigens elicit robust immune responses in swine.

African Swine Fever Virus (ASFV) is a high-consequence transboundary animal pathogen that often causes hemorrhagic disease in swine with a case fatality rate close to 100%. Lack of treatment or vaccine for the disease makes it imperative that safe and efficacious vaccines are developed to safeguard the swine industry. In this study, we evaluated the immunogenicity of seven adenovirus-vectored novel ASFV antigens, namely A151R, B119L, B602L, EP402RΔPRR, B438L, K205R and A104R. Immunization of commercial swine with a cocktail of the recombinant adenoviruses formulated in adjuvant primed strong ASFV antigen-specific IgG responses that underwent rapid recall upon boost. Notably, most vaccinees mounted robust IgG responses against all the antigens in the cocktail. Most importantly and relevant to vaccine development, the induced antibodies recognized viral proteins from Georgia 2007/1 ASFV-infected cells by IFA and by western blot analysis. The recombinant adenovirus cocktail also induced ASFV-specific IFN-γ-secreting cells that were recalled upon boosting. Evaluation of local and systemic effects of the recombinant adenovirus cocktail post-priming and post-boosting in the immunized animals showed that the immunogen was well tolerated and no serious negative effects were observed. Taken together, these outcomes showed that the adenovirus-vectored novel ASFV antigen cocktail was capable of safely inducing strong antibody and IFN-γ+ cell responses in commercial swine. The data will be used for selection of antigens for inclusion in a multi-antigen prototype vaccine to be evaluated for protective efficacy.

Evaluation of a glycerol-preserved antigen in the direct agglutination test for diagnosis of visceral leishmaniasis at rural level in eastern Sudan.

Three-hundred and eight patients with suspected visceral leishmaniasis (VL) were received at Doka Hospital (eastern Sudan) during the period September 2004 to October 2005. The sensitivity and specificity of a glycerol-preserved (GP) antigen for VL diagnosis was assessed against the results of repeated lymph node aspiration and readings from a direct agglutination test (DAT) employing standard formaldehyde-fixed (FF) or freeze-dried (FD) antigen. Despite 13 months of storage at ambient temperature (28-47 degrees C), the GP antigen mean titres obtained from these 308 patients were no different from those that were FD (P=0.945) and stored under similar conditions, but were significantly different (P=0.019) from those that were FF and kept continuously at the optimum temperature for storage (4-8 degrees C). Taking the parasitological result as the gold standard and using a pre-established titre of 1 : 3200 as the DAT cut-off, the GP antigen revealed a sensitivity (91/105, 86.7 %) and specificity (187/203, 92.1 %) comparable to that of FD antigen (92/105, 87.6 %, and 188/203, 92.6 %, respectively) and FF antigen (94/105, 89.5 %, and 188/203, 92.6 %, respectively). At a titre range of 1 : 400-1 : 800, statistically determined as the optimum cut-off for the three antigens, sensitivities of 92.4, 90.5 and 96.2 % and specificities of 90.6, 90.1 and 88.7 % were achieved for the GP, FD and FF antigens, respectively, at a peripheral hospital. Regardless of the antigen preparation used, DAT results obtained in the peripheral hospital were highly reproducible in the central laboratory in Omdurman (weighted kappa: GP=0.957, FD=0.979 and FF=0.936). With a diagnostic reliability comparable to formaldehyde fixation and stability under ambient conditions similar to freeze drying, glycerol preservation, by virtue of its high potential for reproduction, meets the requirements for the management of VL in developing countries.