Effects Of Active Immunization Research Articles

Active immunization by a dengue virus-induced cytokine.

Dengue type 2 virus (DV)-induced cytotoxic factor (CF) is capable of reproducing various pathological lesions in mice that are seen in human dengue. The present study was undertaken to investigate the protective effect of active immunization of mice with CF. Mice were immunized with 5 microgram of CF and prevention of CF-induced increase in capillary permeability and damage to the blood-brain barrier were studied at weekly intervals, up to 48 weeks, by challenging with 3 microgram of CF. Maximum protection against increase in capillary permeability and damage to the blood-brain barrier was observed in week 4 after immunization. A breakthrough in the protection occurred with higher doses of CF in a dose-dependent manner. Challenge with a lethal intracerebral (i.c.) dose of DV showed significantly prolonged mean survival time and delayed onset of symptoms of sickness in the immunized mice compared with the normal mice, but the titre of the virus in the brain was similar in the two groups. On i.p. challenge with the virus the protection against damage to the blood-brain barrier was 86 +/- 7% at week 4 and 17 +/- 4% at week 26 after immunization. Sera obtained from the immunized mice showed the presence of CF-specific antibodies by ELISA, Western blot, and by neutralization of the cytotoxic activity of CF in vitro. The present study describes successful prevention of a cytokine-induced pathology by specific active immunization.

Effects of Active Immunization Against Inhibin Using Two Adjuvants on Hormonal and Daily Sperm Production (DSP) in Ram Lambs.

Effects of Active Immunization Against Inhibin Using Two Adjuvants on Hormonal and Daily Sperm Production (DSP) in Ram Lambs.

Effects of active immunization against cholecystokinin 8 on performance, contents of serum hormones, and expressions of CCK gene and CCK receptor gene in pigs

This study was conducted to investigate the effects of active immunization against cholecystokinin 8 (CCK(8)) on the content of serum CCK, expression of CCK, and CCK receptor gene in pigs. The subjects for this experiment were 15 pigs divided into three groups (5 pigs per group). The treated groups were immunized with CCK(8) conjugated to human serum albumin (HSA). The control group was immunized with same dosage of HSA. The average daily gain of pig fed with 250 microg CCK was significantly increased (P < 0.05), compared with the control group (0 microg CCK). The content of CCK(8), insulin, and leptin in serum was significantly (P < 0.05) decreased and the titer of CCK(8) antibody was significantly (P < 0.05) increased in treated groups compared to the control group. The levels of CCK gene and CCK receptor gene expression in jejunum, pituitary, and pancreas of the treated groups were significantly (P < 0.05) lower than that of the control group. It is concluded that optimal active immunization against CCK(8) could increase the content of CCK antibody and suppress CCK gene and CCK receptor gene expressions and in result improve feed intake and growth performance of pigs.

Prolactin, Luteinizing Hormone and Steroid Hormone Concentration in Punjab Brown (PB3) Birds Immunized Against Vasoactive Intestinal Peptide During the Early Stages of Egg Production

This study aims at the effects of active immunization against chicken Vasoactive Intestinal Peptide (chVIP) on plasma prolactin (PRL) concentration, concentration of Luteinizing Hormone (LH) profile its interval and duration, progesterone (P ), estradiol (E s), intersequence pause days and egg production in 4 2 birds during the initial stages of egg production from 20-36 weeks of egg lay in PB3 birds. Twenty-four PB3 birds of same age group were divided into two groups of twelve in each. Birds in control group were administered s/c with placebo. Equal volume of chVIP immunogenic protein was administered to treate d group from 17th week of age to 36 weeks of age at an interval of four weeks. Hormonal profiles of immunized and control birds were quantified at weekly intervals from 17th to 36th weeks of age in both the groups for prolactin, LH, estradiol, progesterone. Egg production and pause days were recorded in both the groups. At 31st weeks of age, blood samples from chVIP immunized and control birds were obtained every 4 h for 48 hours to study the surges of LH. In immunized PB3 birds (against ch VIP) plasma PRL concentration was lower (p<0.01) with high concentrations of E s, P , LH and, its 4h LH surges, in plasma (p<0.01). Significantly 2 4 higher egg production (9.71%), less pause days were observed in chVIP immunized birds. It is mainly attributed due to low PRL concentration, associated with high concentrations of LH (with regular interval and duration of LH surges), E s and P concentration required for egg formation and subsequent ovulation. In 2 4 conclusion, chVIP immunization advanced the LH surges, for release of matured oocyte, egg formation and egg lay enabled the birds to lay eggs at regular intervals due to active immunization against chVIP. Results indicate that control of chVIP may lead to more egg production with shorter duration of LH surges.

Immunization of pigs against chicken gonadotropin-releasing hormone-II and lamprey gonadotropin-releasing hormone-III: Effects on gonadotropin secretion and testicular function1

The objective of this experiment was to evaluate the effects of active immunization against 2 GnRH isoforms on gonadotropin secretion and testicular function in pigs. Synthetic chicken (c) GnRH-II and lamprey (l) GnRH-III peptides, with the common pGlu-His-Trp-Ser sequence at the N-terminal omitted, were conjugated to BSA. Forty-eight male piglets were randomly assigned to 1 of 4 treatments. Pigs on treatment 1 were actively immunized against cGnRH-II, whereas pigs on treatment 2 were actively immunized against lGnRH-III. Control pigs on treatment 3 were actively immunized against the carrier protein (BSA), and pigs on treatment 4 were castrated and actively immunized against BSA. The BSA conjugate was emulsified in Freund's Incomplete Adjuvant and diethylaminoethyldextran. Primary immunization was given at 13 wk of age (WOA) with booster immunizations given at 16 and 19 WOA. Body weight and plasma samples were collected weekly beginning at 11 WOA. Treatments did not affect BW during the experimental period. Antibody titers were increased in animals immunized against cGnRH-II and lGnRH-III (P < 0.001). Cross-reactivity of the antibodies to mammalian GnRH or between cGnRH-II and lGnRH-III was minimal. Concentrations of testosterone were maximal in control boars (treatment 3) and minimal in control barrows (treatment 4) and immunized pigs (treatment x week; P < 0.01). Immunized animals had concentrations of LH (P < 0.001) and FSH (treatment x week; P < 0.03) that were less than control barrows and similar to control boars. At the end of the experiment, intact (noncastrated) pigs were exsanguinated. Testes were removed immediately; Leydig cells were isolated and treated with 0, 1, or 10 ng/mL of LH. There was an LH x GnRH treatment effect on testosterone concentrations (P < 0.03), indicating that Leydig cells were sensitive to the immunization protocol and doses of LH. Taken together, these data suggest that immunization against GnRH isoforms decreased gonadotropin secretion compared with control barrows. Additionally, immunization against cGnRH-II and lGnRH-III reduced the ability of Leydig cells to respond to LH challenges.

Immunization with 3-oxododecanoyl-l-homoserine lactone–protein conjugate protects mice from lethal Pseudomonas aeruginosa lung infection

Quorum-sensing systems have been reported to play a critical role in the pathogenesis of several bacterial infections. Recent data have demonstrated that Pseudomonas N-3-oxododecanoyl-L-homoserine lactone (3-oxo-C12-homoserine lactone, 3-oxo-C12-HSL), but not N-butanoyl-L-homoserine lactone (C4-HSL), induces apoptosis in macrophages and neutrophils. In the present study, the effects of active immunization with 3-oxo-C12-HSL-carrier protein conjugate on acute P. aeruginosa lung infection in mice were investigated. Immunization with 3-oxo-C12-HSL-BSA conjugate (subcutaneous, four times, at 2-week intervals) elaborated significant amounts of specific antibody in serum. Control and immunized mice were intranasally challenged with approximately 3 x 10(6) c.f.u. P. aeruginosa PAO1, and survival was then compared. All control mice died by day 2 post bacterial challenge, while 36 % of immunized mice survived to day 4 (P<0.05). Interestingly, bacterial numbers in the lungs did not differ between control and immunized groups, whereas the levels of pulmonary tumour necrosis factor (TNF)-alpha in the immunized mice were significantly lower than those of control mice (P<0.05). Furthermore, the extractable 3-oxo-C12-HSL levels in serum and lung homogenate were also significantly diminished in the immunized mice. Immune serum completely rescued reduction of cell viability by 3-oxo-C12-HSL-mediated apoptosis in macrophages in vitro. These results demonstrated that specific antibody to 3-oxo-C12-HSL plays a protective role in acute P. aeruginosa infection, probably through blocking of host inflammatory responses, without altering lung bacterial burden. The present data identify a promising potential vaccine strategy targeting bacterial quorum-sensing molecules, including autoinducers.

The Effect of Active Immunization against Inhibin on Gonadotropin Secretions and Follicular Dynamics during the Estrous Cycle in Cows

The hypothesis of the present study is that active immunization of cows against inhibin would neutralize endogenous inhibin, increase circulating levels of follicle stimulating hormone, and subsequently affect follicular dynamics and the ovulation rate during the estrous cycle. Thirteen cows were immunized against inhibin alpha-subunit and, 6 cows were immunized with a placebo. Both groups were given 4 booster immunizations 7, 14, 21, and 34 weeks after the primary injection. Ovaries were examined daily after the 2nd, 3rd, and 4th booster immunizations by transrectal ultrasonography for 25 days. After the 4th booster immunization, blood samples were collected daily for one complete estrous cycle to measure FSH and LH. The results showed that the immunized cows generated antibodies against inhibin, and that they had higher FSH levels compared with the controls. The number of follicular waves during the estrous cycle was higher in the immunized cows (3 or 4 waves) than in the controls (2 or 3 waves). Moreover, the immunized cows had a greater number of follicles during the estrous cycle compared with the control cows. The maximum number of follicles was 14.8 +/- 1.7 vs 5.4 +/- 0.2 in inhibin-immunized and control cows, respectively, during the first follicular wave and 13.9 +/- 1.9 vs 5.6 +/- 0.7, respectively, during the ovulatory wave. Multiple ovulations were increased in the immunized cows. However, the ovulation rate varied greatly in the immunized animals. In conclusion, immunization against inhibin increased FSH secretions during the estrous cycle in the cows. Moreover, the immunized cows had a greater number of follicular waves during the estrous cycle and a greater number of follicles, and this could be used as a potential source of oocytes for use in IVF/embryo transfer programs.

The effect of active immunization against adrenocorticotropic hormone on cortisol, β-endorphin, vocalization, and growth in pigs1

Because the poor growth performance of intensively housed pigs is associated with increased circulating glucocorticoid concentrations, we investigated the effects of glucocorticoid suppression by inducing a humoral immune response to ACTH on physiological and production variables in growing pigs. Grower pigs (28.6 +/- 0.9 kg) were immunized with amino acids 1 through 24 of ACTH conjugated to ovalbumin and suspended in diethylaminoethyl (DEAE) dextran-adjuvant or adjuvant alone (control) on d 1, 28, and 56. The ACTH-specific antibody titers generated suppressed increases in cortisol concentrations on d 63 in response to an acute stressor (P = 0.002; control = 71 +/- 8.2 ng/mL; ACTH-immune = 43 +/- 4.9 ng/mL) without altering basal concentrations. Plasma beta-endorphin concentrations were also increased (P < 0.001) on d 63 (control = 18 +/- 2.1 ng/mL; ACTH-immune = 63 +/- 7.3 ng/mL), presumably because of a release from negative feedback on the expression of proopiomelanocortin in pituitary corticotropes. Immunization against ACTH did not alter ADG (P = 0.120; control = 1,077 +/- 25; ACTH-immune = 1,143 +/- 25 g) or ADFI (P = 0.64; control = 2,719 +/- 42; ACTH-immune = 2,749 +/- 42 g) and did not modify behavior (P = 0.681) assessed by measuring vocalization in response to acute restraint. In summary, suppression of stress-induced cortisol responses through ACTH immunization increased beta-endorphin concentrations, but it did not modify ADG, ADFI, or restraint vocalization score in growing pigs.

Effect of active immunization against inhibin on hormonal concentrations and semen characteristics in Shiba bucks

Active immunization against inhibin increased ovulation rate in females; in males, the effects of active immunization against inhibin on hormonal concentrations and sperm production need more investigation. To test the hypothesis that active immunization against inhibin increases FSH secretion and sperm output, the present study was undertaken to determine the effects of active immunization against inhibin on hormonal profile and sperm production in Shiba bucks. The bucks were actively immunized against inhibin α-subunit (immunized group, n = 6) or Freund adjuvant (control group, n = 5) four times, at 5-weeks intervals. Blood samples were collected twice-weekly and two successive ejaculates of semen were collected (with an artificial vagina) once-weekly. Plasma concentrations of FSH, LH and testosterone were measured by radioimmunoassay (RIA) and sperm motility characteristics were measured by computer-assisted sperm analysis (CASA). All inhibin-immunized bucks produced antibodies against inhibin. Relative to control bucks, in immunized bucks there were significant increases in plasma FSH concentrations and in sperm concentrations from 5 to 9 weeks and from 8 to 11 weeks, respectively, after primary immunization. However, plasma concentrations of LH and testosterone, semen volume, percentage of motile spermatozoa and motility parameters (straight-line velocity, curvilinear velocity and linearity index) were similar in both groups. In conclusion, active immunization against inhibin α-subunit increased FSH secretions and enhanced sperm production in bucks, whereas LH and testosterone concentrations, semen volume and sperm motility parameters were unaffected. Active immunization against inhibin could be used to improve fertility in Shiba bucks.

Effect of active immunization against GnRH on androstenone concentration, growth performance and carcass quality in intact male pigs

The objective of this study was to investigate the efficacy of active immunization against gonadotropin releasing hormone (GnRH) in male pigs and to compare it with surgical castration. Piglets were randomly assigned to two groups, one of 263 animals for surgical castration (SC) and one of 270 animals for immunocastration (IC). Surgery was done at 14 days of age and vaccination (Improvac®, CSL, Australia) performed twice at an interval of 4–5 weeks with the second injection given 4–7 weeks before slaughter. At slaughter, testes were weighed and fat samples collected for androstenone analysis. Androstenone was tested olfactorially by heating salivary glands in a microwave oven. Daily growth rate and meat quality were assessed in all animals. Regarding mean androstenone concentrations in backfat, no significant difference was found between SC and IC (0.042 (0.041; 0.044) μg/g vs. 0.058 (0.044; 0.071) μg/g; mean (95% confidence interval)). Testes weight was significantly ( P<0.001) smaller in immunized (230.8 g (218.23; 243.52)) as compared to normal boars (761.8 g (722.77; 801.01)) of the same age, as a reference. In this study, androstenone production was suppressed in all vaccinated animals and the carcasses given free for consumption. Mean daily growth gain was not significantly different between SC (0.817 kg (0.804; 0.830)) and IC (0.827 kg (0.814; 0.840)), although there was a trend for better performance in the latter group. The yield of lean meat was significantly ( P<0.001) improved in IC (54.50% (54.26; 54.73)) when compared to SC (53.76% (53.53; 54.00)). From our results, we conclude that vaccination against GnRH is a practical and effective method to suppress androstenone synthesis. Pain and stress associated with surgical castration can thus be avoided.

Active Immunization against Inhibin Improves Superovulatory Response to Exogenous FSH in Cattle

The effect of active immunization against inhibin on the response to superovulatory treatment by porcine FSH (pFSH) was investigated in cattle. Japanese black cows were sc injected with 1 mg of porcine inhibin alpha-subunit fragment (1-26) conjugated with rabbit serum albumin (inhibin-immunized group; n=14) or rabbit serum albumin alone (control group; n=12) in Freund's complete adjuvant. Booster injections (half the amount of the primary injection) were given 35 and 70 days after the primary injection. All cows were superovulated three times with pFSH. Three days after each injection of the antigen, a progesterone-releasing intravaginal device (CIDR-B) was inserted vaginally into all animals and left in place for 10 days. Forty-eight hours before CIDR-B removal, all animals were sc injected with 30 mg pFSH dissolved in 40% polyvinylpyrrolidone, and im injected with 750 microg of PGF2alpha at CIDR-B removal. Cows were artificially inseminated twice during estrus, and ova or embryos were collected 7 or 8 days after estrus. The number of corpora lutea, the number of ova or embryos and the number of transferable embryos in inhibin-immunized cows (12.1+/-1.2, 11.1+/-1.3 and 6.2+/-1.0, respectively) were significantly greater than those in the controls (8.2+/-1.0, 5.7+/-1.1 and 3.1+/-0.7, respectively). These results indicate that active immunization against inhibin enhanced ovarian response to the usual superovulatory treatment in cattle. Therefore, immunization against inhibin may be a useful approach for improving the response to superovulation in cattle.

Immunotropic effects of active immunization with serotonin-protein conjugate in C57BL/6 mice exposed to immobilization stress.

Immobilization stress for 14 h induced lymphopenia, hypoplasia of the thymus and spleen, and decrease in functional activity of T lymphocytes and macrophages in C57Bl/6 mice. Active induction of antibodies against serotonin during stress decreased functional activity of T lymphocytes and partially recovered phagocytic activity of peritoneal macrophages.

Elevation of Corazol-Induced Seizure Threshold after Active Immunization of Mice of Various Genetic Strains with Glutamate-Bovine Serum Albumin Conjugate

We studied the effect of active immunization with glutamate-bovine serum albumin conjugate on acute generalized epileptiform activity evoked by single administration of corazol. Antibodies to glutamate produced an antiepileptic effect and elevated the threshold for clonic seizures and tonic phase of lethal seizures. In BALB/c mice this effect was more pronounced than in C57BL/6 mice.

Sexual development and the effects of active immunization against GnRH in Chinese Tanyang ram lambs

Tanyang is one of the most important sheep breeds in the northwest of China. However, there is no detailed data on sexual development and timing of puberty/sexual maturity of this breed. This experiment was designed to study the relationships between growth rate and sexual development by measuring body weight, testis diameter, and plasma testosterone concentrations, and observing sexual behavior through puberty from 3 to 8 months old of entire Tanyang ram lambs. At same time, to assess the potential efficacy and welfare benefits of non-surgical castration, the effect of active immunization against gonadotrophin-releasing hormone (GnRH) on sexual development and growth rate on ram lambs was evaluated, and compared with surgically castrated and entire lambs. The results showed that body weight increased at a constant rate from 3 to 8 months old of age. Testis diameter increased rapidly between 3 and 5 months, followed by a period of slow growth. Plasma testosterone concentrations increased sharply from 3 to 6 months of age ( P<0.05), after which there were no significant changes from 6 to 8 months of age. Sexual behavior started from 5 months of age. After ram lambs were immunized against GnRH at 3 months of age, there was no increase in testis diameter in the first 4 months after immunization. Plasma testosterone concentrations remained at similar levels to surgically castrated lambs until 6 months of age, and the onset of sexual behavior was delayed, compared with entire ram lambs. GnRH immunization and surgical castration had no significant effect on the body weight by the end of this experiment. These results suggest that 4–5 months of age is a critical period for pubertal changes and testosterone plays an important role in the initiation of puberty and sexual maturity of Tanyang ram lambs in China. In addition, a single shot GnRH immunization at 3 months, acting as an alternative to surgical castration, is a practical method for Chinese Tanyang ram lambs, and provides animal welfare benefits.

Effects of active immunization against GnRH on serum LH, inhibin A, sexual development and growth rate in Chinese female pigs

Surgical castration of young female pigs is common practice in Chinese pig farming today. The purpose of the present study is to investigate anti-GnRH immunization as a practical alternative to surgical castration for female pigs. Thirty-six Chinese female crossbred pigs (Chinese Yanan×Yorkshire) were selected from 12 litters, three pigs from each litter, at the age of 10–13 weeks. One pig from each litter was immunized with 62.5 μg d-Lys6-GnRH-tandem-dimer peptide conjugated to ovalbumin in Specol adjuvant at Week 0 (0 week post-vaccination, wpv), and a booster vaccination was given 8 weeks later (8 wpv). Its intact and castrate littermates (surgically castrated at the time of weaning, i.e. at 6 weeks of age) were administered the vehicle and served as controls. Antibody titers, serum LH and inhibin A were determined at the day of first vaccination, every 4 weeks thereafter and at the day of slaughter (18 wpv). At slaughter, ovaries were inspected for the presence of follicles and corpora lutea, and ovarian and uterine weights were recorded. Ten of twelve immunized pigs responded well to the immunization (immunocastrated animals), while the remaining two pigs responded poorly (nonresponders). Antibody titres in immunocastrated animals steadily increased after immunization, became maximal at 12 wpv and remained high until slaughter. Serum LH levels were reduced ( P<0.05) in immunocastrated pigs as compared to intact controls and surgical castrates. Serum inhibin A levels decreased after vaccination, and equaled surgical castrate levels from 8 wpv until the end of the experiment. Ovarian and uterine weights (1.3±0.2 and 43.9±11.4 g, respectively; mean±S.E.M.) were significantly lower ( P<0.05) in immunocastrates than in intact controls (9.4±1.1 and 390.9±67.2 g, respectively). Antibody titers were significantly lower ( P<0.05) in nonresponders than in immunocastrated pigs from 12 wpv to slaughter. Ovarian and uterine weights were similar in nonresponders and in intact controls. Macroscopically, no follicular structures were found in ovaries of immunocastrated pigs, while large follicles or corpora lutea were observed in the ovaries of both nonresponders and intact controls. Although not significant, immunocastrates had a numerically higher average daily gain than surgical castrates and intact controls (0.74±0.04 versus 0.66±0.04 versus 0.66±0.03 kg per day, respectively; mean±S.E.M., P=0.09). Results obtained in the present study demonstrate that anti-GnRH immunization can be an attractive alternative to surgical castration for Chinese crossbred female pigs. Our results also question the beneficial effect of surgical castration on growth as compared to intact controls.

Effects of Active Immunization against Somatostatin or its Analogues on Milk Protein Synthesis of Rat Mammary Gland Cells

Effects of active immunization against native 14-mer somatostatin (SRIF, somatotropin releasing inhibiting factor) and its two 14-mer-somatostatin analogues on the milk production in rat mammary cells were studied. NativeSRIF, Tyr11-somatostatin (Tyr11-SRIF), and D-Trp8, D-Cysl4-somatostatin (Trp8Cys14-SRIF) were conjugated to bovine serum albumin (BSA) for immunogen preparation. Twenty-four female Sprague-Dawley rats were divided into four groups and immunized against saline (Control), SRIF, Tyr11-SRIF, and Trp8Cysl4-SRIF at five weeks of age. Booster immunizations were performed at 7, 9, and 11 weeks of age. SRIF-immunized rats were mated at 10 weeks of age. The blood and mammary glands were collected at day 15 post-pregnancy and -lactation. To measure the amount of milk protein synthesis in the mammary gland, mammary cells isolated from the pregnant and the lactating rats, were cultured in the presence of 3 H-lysine. No significant differences in growth performance, concentration of growth hormone in the circulation, and the amount of milk protein synthesis were observed among the groups. Inductive levels of serum anti-SRIF antibody in the SRIF and Tyr11-SRIF groups but not in the Trp8Cys14-SRIF group, were significantly higher than that of the control group during the pregnancy and lactation periods. The result suggests that active immunization against native 14-mer SRIF and Tyr11-SRIF was able to induce anti-SRIF antibodies, but did not affect the milk protein synthesis.

Adrenal influence on the persistence of pseudopregnancy in rats.

The effect of adrenalectomy on the duration of pseudopregnancy was investigated in rats. When adrenalectomy was performed three days before cervical stimulation or when it was done on the first day (day 1, day of estrus) or day 2 of pseudopregnancy, the duration of the pseudopregnancy was significantly prolonged (3.0, 2.5 and 1.8 days respectively). This effect of adrenalectomy was not seen when operation was delayed until day 4 of pseudopregnancy. Adrenalectomy on day 2 of pseudopregnancy significantly increased prolactin (PRL) release at the time of the nocturnal PRL surge (5:00) on day 7. When rats were ovariectomized simultaneously with adrenalectomy on day 1, the stimulating effect of adrenalectomy on PRL release was more evident. The effect of active immunization against corticosterone on the continuation of pseudopregnancy was also examined. Neutralization of plasma corticosterone extended the duration of pseudopregnancy and the binding activity of the antiserum positively correlated with the length of continuing diestrus (P < 0.05). These results indicate the negative effect of the adrenal glands, which is probably due to corticosterone, on PRL release in pseudopregnant rats and that the early relief of this inhibition extends the duration of pseudopregnancy.

Antibodies to glutamate as neuromodulators of behavioral reactions in mice with various genotypes.

We studied the effects of active immunization with glutamate-protein conjugates on behavioral reactions of C57Bl/6 and BALB/c mice in the open-field test and on animal anxiety in the tail suspension test. Antiglutamate antibodies produced different behavioral changes in mice of these strains.

Effects of active immunization with inhibin alpha subunit on reproductive characteristics of turkey hens.

The hypothesis for the present study is that the active immunization of female turkeys with inhibin (INH) would neutralize endogenous INH, and increase levels of circulating follicle stimulating hormone (FSH) and the number of preovulatory follicles, and subsequently enhance egg production. Two experiments were conducted with female turkeys in their first (30 wk of age) and second (62 wk of age) laying cycles. Treatment groups included control turkeys immunized with keyhole limpet hemocyanine (KLH) and experimental turkeys immunized with recombinant turkey inhibin alpha conjugated to KLH (rtINH), vasoactive intestinal peptide (VIP) conjugated to KLH or rtINH+VIP. Egg production increased (P < 0.05) in VIP and rtINH+VIP immunized birds, but not in rtINH immunized hens in comparison with a control group. A similar number of ovarian follicles, arranged in the follicular hierarchy of laying hens, was observed in all experimental groups. However, there was a larger number of nongraded yellow follicles in rtINH-immunized (62.5%) and rtINH+VIP-immunized (73.5%) groups compared with that of controls, suggesting overstimulation by FSH. Anterior pituitary FSH beta subunit, LH beta subunit, and prolactin (PRL) mRNA contents were determined by Northern blot analysis and reverse transcriptase-polymerase chain reaction (RT-PCR) in laying hens at the end of the experimental period. Hens immunized with rtINH showed increased FSH beta subunit mRNA content, but no change in the content of LH beta subunit or PRL mRNA. Hens immunized with VIP or rtINH+VIP had significant increases in both pituitary LH beta subunit and FSH beta subunit mRNA contents, accompanied by a decline in PRL mRNA abundance. The magnitude of the increase in FSH beta subunit to INH immunoneutralization was greater in first-cycle hens than in second-cycle hens. These data suggest that active immunization of female turkeys with INH neutralizes endogenous INH and increases both circulating FSH and the number of preovulatory follicles. However, no significant increase in egg production was observed in INH-immunized hens. The data confirm previous reports that VIP immunoneutralization increases egg production in turkey hens and shows for the first time that it also increases FSH beta subunit and LH beta subunit gene expression.

Effects of Active Immunization against Somatostatin or Somatostatin Analogues on Male Rat Growth

Effects of active immunization against somatostatin (SRIF) or various forms of somatostatin analogues on growth were investigated in male rats. In experiment 1, SRIF14, SRIF28, octreotide, Tyr 3 -octreotide or MK 608 were conjugated to human serum globulin and used as immunogens. Thirty-five Sprague-Dawley male rats were divided into seven groups and immunized against phosphate-buffered saline (PBS) (control 1), or one of the conjugated immunogens at five weeks of age. Booster immunizations were performed at 7, 9 and 12 weeks of age. Only SRIF14 induced the production of anti-somatostatin antibodies. There were no differences in blood GH concentration and growth performance between the SRIF14 group (with anti-SRIF antibodies) and other groups (without the antibodies). Although growth performance for the whole period was not affected by immunization with SRIF14 conjugate, daily weight gain and feed efficiency for 2 weeks after the third booster immunization were significantly improved, suggesting that the production of antibody against somatostatin can reach the minimal level for improving growth performance only after the third booster immunization in male rats. Experiment II was designed as a 2 2 2 2 2 factorial arrangement in which SRIF14 or Tyr11-SRIF14 was conjugated onto thyroglobulin or keyhole limpet haemocyanin (KLH) by glutaraldehyde or m-maleimidobenzoyl-N-hydroxysuccinimide coupling methods, and the immunization schedule was the same as experiment I. Anti-SRIF antibody titre values of the rats that received the conjugated SRIF14 or Tyr 11 -SRIF14 were higher than those injected with PBS. The levels of anti-SRIF antibody were not affected by the different coupling methods or by the different carrier proteins. In the Ag3 group treated with SRIF14 + KLH conjugate, total weight gain for the whole period and feed efficiency for 2 weeks after the third booster immunization were significantly different from other groups. Although GH concentration in blood was not changed by the production of antibody, our results show the possibility that active immunization against SRIF can improve growth performance in the male rat and SRIF14 peptide may be a potential candidate for active immunization.