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    Gamete Therapeutics: Recombinant Protein Adsorption by Sperm for Increasing Fertility via Artificial Insemination

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    A decrease in fertility can have a negative economic impact, both locally and over a broader geographical scope, and this is especially the case with regard to the cattle industry. Therefore, much interest exists in evaluating proteins that might be able to increase the fertility of sperm. Heparin binding proteins (HBPs), specifically the fertility associated antigen (FAA) and the Type-2 tissue inhibitor of metalloproteinase (TIMP-2), act to favor the capacitation and acrosome reaction and perhaps even modulate the immune system's response toward the sperm. The objective of this research was to determine the effect on fertility of adding recombinant FAA (rFAA) and recombinant TIMP-2 (rTIMP-2) to bovine semen before cryopreservation for use in an artificial insemination (AI) program in a tropical environment. For this experiment, 100 crossbred (Bos taurus x Bos indicus) heifers were selected based on their estrus cycle, body condition score (BCS), of 4 to 6 on a scale of 1 to 9, and adequate anatomical conformation evaluated by pelvic and genital (normal) measurements. Heifers were synchronized using estradiol benzoate (EB), Celosil® (PGF2α) (Shering-Plough) and a controlled internal drug release (CIDR) device was inserted that contained progesterone. Inseminations were performed in two groups at random, 50 animals per group. The control group was inseminated with conventional semen. The treatment group was inseminated with semen containing rFAA (25 µg/mL) and rTIMP-2 (25 µg/mL). In the control group a 16% pregnancy rate was obtained versus a 40% pregnancy rate for the HBP treatment group, resulting in a significant difference (P = 0.0037). Given the results herein, one may conclude that the HBPs can increase fertility and could be an option for cattle in tropical conditions; however, one needs to consider the environment, nutrition, and the genetic interaction affecting the final result in whatever reproductive program that is implemented

    Visualization of representative control and treatment sperm samples included the following: a) fertility associated antigen (FAA) antibody control sample (FAA negative) without FAA present on sperm (provided by Midland Bioproducts Corporation®) and verified after the application of fluorescein conjugated FAA antibody, b) FAA protein control sample (FAA negative, provided by Midland Bioproducts Corporation®) with fluorescein conjugated FAA recombinant protein added to sperm, c) fluorescein conjugated Type-2 tissue inhibitor of metalloproteinase (TIMP-2) antibody added to sperm, and d) fluorescein conjugated TIMP-2 protein added to sperm.

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    <p>Visualization of representative control and treatment sperm samples included the following: a) fertility associated antigen (FAA) antibody control sample (FAA negative) without FAA present on sperm (provided by Midland Bioproducts Corporation®) and verified after the application of fluorescein conjugated FAA antibody, b) FAA protein control sample (FAA negative, provided by Midland Bioproducts Corporation®) with fluorescein conjugated FAA recombinant protein added to sperm, c) fluorescein conjugated Type-2 tissue inhibitor of metalloproteinase (TIMP-2) antibody added to sperm, and d) fluorescein conjugated TIMP-2 protein added to sperm.</p

    Fitted model of the logistic regression analysis of the pregnancy rates for estimating the percentages of gestations under the different experimental conditions: .

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    <p>Null deviance: 30.63 on 3 degrees of freedom.</p><p>Residual deviance: 1.5 on 1 degree of freedom.</p><p>Akaike Information Criterion (AIC): 17.8.</p><p><i>r</i>HBPs = recombinant heparin binding proteins, 0 or 1 for the treatment or control group, respectively.</p><p>BCS = body condition score, 0 or 1 for BCS = 4 or 6, respectively.</p

    Percentages of controlled internal drug release (CIDR) devices retained, presentation of estrus and gestations summarized for the different groups.

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    <p>Group A (Control) = crossbred heifers inseminated with cryopreserved, frozen-thawed sperm without added recombinant heparin binding proteins (<i>r</i>HBPs), i.e., control group. Group B (<i>r</i>HBPs) = crossbred heifers inseminated with cryopreserved, frozen-thawed sperm with added <i>r</i>HBPs, i.e., treatment group.</p
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