Looking at Cell Wall Components with Our Customers in Mind

Fiber digestibility of alfalfa for animal nutrition is a complex system encapsulating animal, plant, and microbe biological traits. Understanding all components within the system is key to predicting forage quality. We investigated the relationship between alfalfa cell wall components and invitro neutral detergent fiber digestibility (IVNDFD) speed (16-hr) and potential (96-hr) of by cattle ruminant microbes. A composite alfalfa (Medicago sativa L.) population from seven commercial cultivars underwent two cycles of bidirectional selection for plants with low or high stem 16-hr IVNDFD and low or high stem 96-hr IVNDFD. The resulting selected populations were then evaluated by near inferred spectrometry for structural cell wall components and thier relationship with IVNDFD. Hemi-cellulose and cellulose components were found to have a greater negative correlation (-0.85 & -0.86) on the speed of digestion (16-hr IVNDFD) than lignin (-0.70). Whereas, for the overall potential of stem digestibility, lignin (-0.89) had the greatest negative correlation. The relationship between cellulose and lignin with IVNDFD was futher supported with the use of a path model. Lignin and 96-hr IVNDFD had the strongest broad sense heritability across the populations (0.74 & 0.70 respectively). Pectin components correlated positively with speed of digestion (0.41) but had limited correlation on the overall digestibility potential. As IVNDFD increased with each breeding cycle, it remained stable across environments along with concentrations of total cell wall components, lignin, hemi-cellulose, and pectin. However, the cellulose concentrations were not stable across environments. Cell wall components such as hemi-cellulose and lignin could be used as selection traits for increased IVNDFD breeding and may be a way to link invitro digestibility to plant trait genes for genomic selection

Induction of neutralizing antibodies specific for the envelope proteins of the koala retrovirus by immunization with recombinant proteins or with DNA

Background: The koala retrovirus (KoRV) is the result of a transspecies transmission of a gammaretrovirus with fatal consequences for the new host. Like many retroviruses, KoRV induces lymphoma, leukemia and an immunodeficiency that is associated with opportunistic infections in the virus-infected animals. We recently reported the induction of neutralizing antibodies by immunization with the recombinant ectodomain of the transmembrane envelope protein p15E of KoRV. Since the neutralization titers of the p15E-specific sera were only moderate, we investigated the use of the surface envelope protein gp70 to induce neutralizing antibodies. Findings: We immunized rats and goats with the recombinant gp70 protein of the KoRV, an unglycosylated protein of 52kD (rgp70/p52) or with the corresponding DNA. In parallel we immunized with recombinant rp15E or with a combination of rp15E and rgp70/p52. In all cases binding and neutralizing antibodies were induced. The gp70-specific sera had titers of neutralizing antibodies that were 15-fold higher than the p15E-specific sera. Combining rp15E and rgp70/p52 did not significantly increase neutralizing titers compared to rgp70/p52 alone. High titers of neutralizing antibodies specific for gp70 were also induced by immunization with DNA. Since KoRV and PERV are closely related, we investigated cross-neutralization of the antisera. The antisera against p15E and gp70 of PERV and KoRV inhibited infection by both viruses. Conclusion: The envelope proteins of the KoRV may therefore form the basis of an effective preventive vaccine to protect uninfected koalas from infection and possibly an immunotherapeutic treatment for those already infected