Albumin-binding domain from Streptococcus zooepidemicus protein Zag as a novel strategy to improve the half-life of therapeutic proteins

Recombinant antibody fragments belong to the promising class of biopharmaceuticals with high potential for future therapeutic applications. However, due to their small size they are rapidly cleared from circulation. Binding to serum proteins can be an effective approach to improve pharmacokinetic properties of short half-life molecules. Herein, we have investigated the Zag albumin-binding domain (ABD) derived from Streptococcus zooepidemicus as a novel strategy to improve the pharmacokinetic properties of therapeutic molecules. To validate our approach, the Zag ABD was fused with an anti-TNFα single-domain antibody (sdAb). Our results demonstrated that the sdAb-Zag fusion protein was highly expressed and specifically recognizes human, rat and mouse serum albumins with affinities in the nanomolar range. Moreover, data also demonstrated that the sdAb activity against the therapeutic target (TNFα) was not affected when fused with Zag ABD. Importantly, the Zag ABD increased the sdAb half-life ∼39-fold (47min for sdAb versus 31h for sdAb-Zag). These findings demonstrate that the Zag ABD fusion is a promising approach to increase the half-life of small recombinant antibodies molecules without affecting their therapeutic efficacy. Moreover, the present study strongly suggests that the Zag ABD fusion strategy can be potentially used as a universal method to improve the pharmokinetics properties of many others therapeutics proteins and peptides in order to improve their dosing schedule and clinical effects.

Administration of recombinant bovine somatotropin to dairy cows for four consecutive lactations

Effects of long-term administration of recombinant bovine somatotropin (bST) to dairy cows on complete lactational performance [60 (+/- 3) to 284 (+/- 3) d in milk (DIM)] were studied for four consecutive lactations. Beginning on d 60 (+/- 3) postpartum, Holstein cows received biweekly injections (500 mg) of bST (n = 39) or a placebo (control; n = 39) during the first lactation of the study. Cows either continued on the same treatment (n = 26) or were switched to the opposite treatment (n = 29) during the second lactation. Cows that changed treatments were injected for only 16 wk during the second lactation. Six cows per treatment completed four consecutive lactations. Treatment with bST during the first lactation did not have a residual effect on milk yields during the second lactation. Injections of bST during the second lactation increased milk yield 6.5 kg/d from 60 (+/- 3) to 172 DIM. For the four lactations, cows receiving bST yielded 3.7 kg/d (14%) more milk and gained 52 kg (37%) more body weight than did controls. Pretreatment (from 0 to 56 DIM) milk yields in yr 2, 3, and 4 were not affected by previous bST treatment. Milk yield, efficiency of feed utilization, and body weights were enhanced in cows injected with bST for four consecutive lactations. Previous bST treatment did not diminish milk yields in subsequent lactations.

Effect of source and amount of supplemental fat on lactation and digestion in cows

Thirty Holstein cows averaging 50 DIM were assigned to five dietary treatments for 75 d to determine the effects of source and amount of supplemental fat on milk yield, milk composition, and nutrient digestibilities. Diets were 1) control, 2) diet 1 plus 12% whole cotton-seed, 3) diet 2 plus 2.2% safflower oil, 4) diet 2 plus 2.2% prilled tallow fatty acids, and 5) diet 2 plus 4.4% prilled tallow fatty acids. Milk yield was increased an average of 2.1 kg/d by addition of 2.2% prilled tallow fatty acids or safflower oil to the diet (7% fatty acids) containing 12% whole cottonseed. However, when fatty acids were increased to 9.1% with additional prilled tallow fatty acids, milk yield, DMI, and fatty acid digestibility decreased. Whole cottonseed alone and in combination with all fat additions decreased milk protein concentrations. Safflower oil increased C18:0, C18:1, and C18:2 fatty acids in milk. Digestibilities of OM, NDF, and ADF were not affected by diet. Supplementation of a saturated or unsaturated fat source to increase fatty acid content to 7.0% of dietary DM increased milk yield, but a further increase in fat to 9.1% with the saturated source appeared excessive for cows yielding 30 to 35 kg/d of milk.

Influence of microbial colonization of feed particles on determination of nitrogen degradability by in situ incubation

Stable 15N isotope was used to determine the extent of microbial colonization of in situ incubation residues and the influence of colonization on estimates of ruminal degradability of feed N. In an in vitro trial, 15N:total N ratio remained unchanged after the soluble (by water, saline, or buffer solution) fraction of plant N was removed, suggesting that 15N was uniformly distributed in the soluble and insoluble N fractions. In three in situ trials, corn grain, corn husks, and alfalfa hay labeled with 15N as an internal marker were incubated in Dacron bags in the rumen of two lactating Holstein cows for 3, 6, 12, 24, 36, and 48 h. Enrichment of 15N in samples decreased with increased time of incubation for all feeds. At 48 h of incubation, 31, 71, and 65% of the residual N was microbial N for corn grain, corn husks, and alfalfa hay, respectively. Bacterial cell DM, as a percentage of residual DM, increased in a quartic manner, suggesting that microbial colonization depended on substrate availability. For 24, 36, and 48 h incubation, bacterial DM, as a percentage of total residue, averaged 10.0 +/- 1.0% for corn grain, 17.5 +/- 1.4% for corn husks, and 22.0 +/- .2% for alfalfa hay. Apparent degradability of N after 48 h of incubation was approximately 65% for corn grain and alfalfa hay and 19% for corn husks. When corrected for bacterial N, degradabilities of N in all feeds increased and the degradabilities for corn husks became similar to those for corn grain.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of three supplemental fat sources on lactation and digestion in dairy cows

Tallow, Ca salts of palm fatty acids, or prilled fatty acids were added at 2.5% to a control diet (3.7% fatty acids) containing 7.2% ammoniated whole cottonseed. Diets were fed to midlactation cows (6 cows per treatment) for 72 d to determine effects of fat supplementation and fat source on lactation performance and nutrient digestibilities. Dry matter intake did not differ among treatments. Milk yield was 31.6 kg/d for the control and increased an average of 2.1 kg/d with fat supplementation. Source of supplemental fat did not significantly affect lactation performance. Added fat decreased milk protein content but did not affect protein yield. Milk fat, lactose, and SNF contents did not differ among treatments. Overall fat supplementation did not affect digestibilities of DM, ADF, or NDF but decreased digestibility of fatty acids. Contribution of de novo fatty acids to milk fat was decreased with fat supplementation. Addition of 2.5% fat to a diet containing a medium amount of fat from whole cottonseed increased milk yield. Tallow, Ca salt of palm fatty acids, and prilled fatty acids did not differ in milk yield response.