Immunization against Rumen Methanogenesis by Vaccination with a New Recombinant Protein.

Vaccination through recombinant proteins against rumen methanogenesis provides a mitigation approach to reduce enteric methane (CH4) emissions in ruminants. The objective of present study was to evaluate the in vivo efficacy of a new vaccine candidate protein (EhaF) on methanogenesis and microbial population in the rumen of goats. We amplified the gene mru 1407 encoding protein EhaF using fresh rumen fluid samples of mature goats and successfully expressed recombinant protein (EhaF) in Escherichia coli Rosetta. This product was evaluated using 12 mature goats with half for control and other half injected with 400ug/goat the purified recombinant protein in day 1 and two subsequent booster immunizations in day 35 and 49. All measurements were undertaken from 63 to 68 days after the initial vaccination, with CH4 emissions determined using respiration calorimeter chambers. The results showed that the vaccination caused intensive immune responses in serum and saliva, although it had no significant effect on total enteric CH4 emissions and methanogen population in the rumen, when compared with the control goats. However, the vaccination altered the composition of rumen bacteria, especially the abundance of main phylum Firmicutes and genus Prevotella. The results indicate that protein EhaF might not be an effective vaccine to reduce enteric CH4 emissions but our vaccine have potential to influence the rumen ecosystem of goats.

Development of a vaccine to mitigate greenhouse gas emissions in agriculture: vaccination of sheep with methanogen fractions induces antibodies that block methane production in vitro.

AIM: To develop an understanding of the immune responses of ruminants to methanogens, and to provide proof of a concept that harnessing the immune system of ruminants is a potentially viable approach to mitigate greenhouse gas emissions from agriculture. METHODS: Four subcellular fractions, namely cytoplasmic, two cell-wall preparations, and cell wall-derived proteins were prepared from Methanobrevibacter ruminantium M1. Twenty sheep (10 months of age) were vaccinated with these fractions or with whole cells (n=4 per group). Sheep were re-vaccinated once after 3 weeks, and antibody responses to M. ruminantium M1 antigens in sera and saliva measured using ELISA at 2 weeks after the second vaccination. Antigens recognised by the antisera were visualised using Western blotting. The antisera were tested in vitro for their impact on M. ruminantium M1, measuring the effect on cell growth, methane production, and ability to induce agglutination. RESULTS: Basal levels (pre-vaccination) of antibodies against M. ruminantium M1 antigens were low. Vaccination with the antigenic fractions induced strong antibody responses in serum. Both IgG and IgA responses to methanogen antigens were detected in saliva following vaccination. Western blot analysis of the antisera indicated reactivity of antibodies, and a wide range of proteins was present in the different methanogen fractions. Antisera against the various fractions agglutinated methanogens in an in-vitro assay. In addition, these antisera decreased the growth of a pure culture of a methanogen and production of methane in vitro. CONCLUSIONS: Antigens from methanogens are immunogenic in ruminants, and antisera from sheep vaccinated with fractions of methanogens have a significant impact on these organisms, inducing cell agglutination, and decreasing growth of methanogens and production of methane. Only antisera to selected methanogen fractions were able to achieve these effects. The results demonstrate the feasibility of a vaccination strategy to mitigate emission of methane.

Temporal evolution of the sensitivity to tetranitromethane of the active site of anti-Tobacco mosaic virus antibodies.

Rabbit anti-TMV antibody taken 9 days after antigen injection is inactivated by much lower concentrations of tetranitomethane (TNM) than anti-body taken after 30 days. This change in sensitivity to TNM occurs in a very heterogeneous population of molecules, including IgM and IgG classes, but the affinity of the antibody remains unchanged. Thus, the phenomenon is not the result of selection of antibody-producing cells under the influence of antigen. Inactivation of early anti-TMV antibody appears to result from the nitration of one tyrosyl residue per Fab fragment. This tyrosine is probably located in the heavy chain and most probably in the variable portion. The moderate sensitivity of late anti-body to TNM is attributed to the lower reactivity of a tyrosine in the active site, and to the fact that nitration of this tyrosine does not inactivate the binding site. The suggested interpretation is that the majority of molecules of a very heterogeneous anti-TMV antibody pool may have a common structure in their active site during the early stage of the antibody response. This may later be replaced in most molecules by different structures.