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Journal ArticleDOI

Pathophysiology of white-tailed deer vaccinated with porcine zona pellucida immunocontraceptive

TL;DR: White-tailed deer were examined postmortem to identify any possible pathophysiology resulting from PZP immunocontraception vaccination, and the vaccine elicited ovarian pathologies in deer similar to those observed in other species.
About: This article is published in Vaccine.The article was published on 2007-06-06 and is currently open access. It has received 47 citations till now. The article focuses on the topics: Porcine zona pellucida & Oophoritis.

Summary (4 min read)

1. Introduction

  • Porcine zona pellucida (PZP) antigen has been the most commonly used immunocontraceptive agent for fertility control in female mammals [1,2] and has been administered to 112 species of wildlife, including many ungulate species [3].
  • Previous investigators have reported the success and reversibility of PZP vaccination with minimal effect on the health of white-tailed deer (Odocoileus virginianus) [4–6].
  • Since that time, a study was conducted on domestic sheep (Ovis aries), a cervid species that demonstrated marked changes in estrous cycling and hormone levels associated with severely pathologic ovaries [16].
  • Species- and breed-specific responses to PZP vaccinations vary both in successful fertility control, and in pathologic symptoms [10,12,13,16–20].

2. Materials and methods

  • Postmortem examinations were performed promptly on a sample of white-tailed deer in accordance with a protocol (No. 96-10-99) amendment approved by the Cornell University Institutional Animal Care and Use Committee.
  • The deer had been injected with a porcine zona pellucida vaccine (PZP, n = 14), or left untreated (controls; n = 7) during the period 1997–2000 as a part of a fertility control study conducted on free-ranging deer contained in a 263-ha fenced, natural area at Seneca Army Depot near Romulus, New York [7].

2.1. Vaccine formulation

  • Female deer were immunized with native porcine zona pellucida prepared by and purchased from B. Dunbar (Baylor College of Medicine, Houston, TX) [20–22].
  • A 1-cc prime dose of PZP vaccine consisted of 0.5 cc saline containing 100 g PZP mixed with 0.5 cc Complete Freund’s Adjuvant (CFA).

2.2. Vaccination protocol

  • The primary vaccination (PZP + CFA) was injected by hand into the hip region of female deer during winter 1997 as they were captured for recruitment into the study.
  • At the time of capture, deer were marked with numbered ear tags and neck collars.
  • Age was determined by the extent of tooth wear [23], and deer were released into the fenced study area.
  • The first booster shot (PZP + IFA) was administered remotely via dart rifle with self-injecting 1-cc darts (Pneu Dart Inc., Williamsport, PA) prior to breeding season, 5–7 months later in September 1997.
  • Booster treatments were suspended until September 2000 when six female deer were revaccinated (PZP + IFA) to provide the comparison of recently-vaccinated deer to those previously treated 2 years earlier.

2.3. Deer collection and gross necropsies

  • In October 2000, within permit authority from the New York State Department of Environmental Conservation , deer were humanely killed by a shot to the head or neck from a high-powered rifle fired from a blind or a vehicle [24].
  • Blood samples were immediately collected via heart puncture at the time of death and were stored in vials on ice for transport.
  • Gross examinations included evaluation of body condition and bone marrow fat [25], examination of injection sites, and documentation of any visible abnormalities.
  • Ovaries, internal iliac lymph node, popliteal lymph node, and thyroid glands were stripped of fat and connective tissue then weighed immediately (nearest mg).
  • Histological analysis was performed on tissues fixed in formalin, embedded in paraffin, cut to 7 thickness, and stained with hemotoxylin and eosin, Masson’s Trichrome, or acid fast stains.

2.4. Serology

  • Blood chemistry analysis was performed by the Cornell University College of Veterinary Medicine, Animal Health Diagnostic Center on all of the collected deer.
  • Anti-PZP titers (titer−1 × 1000) titers were determined via an enzyme-linked immunosorbent assay as described by Miller et al. [15] and were compared to ovarian weights and histology.

2.5. Follicle classification

  • Each ovary was halved before fixation in formalin, and each half was embedded in paraffin.
  • Multiple sections (but not step sections) were made of each surface to be examined with several stains, and if a suspected lesion was observed grossly, a section was also made through the lesion.
  • The total number of secondary and Graafian follicles were enumerated from two cross-sectional slices from each ovary from each deer.
  • Apoptosis was characterized as granulosa cells with dark, small consolidated nuclei with an absence of heterochromatin.
  • Because none of these follicles exceeded 1 cm in diameter, they were classified as atretic Graafian follicles; however, they could have been small follicular cysts.

3.2. Body condition and fat reserves

  • On the basis of body weight, external visibility of individual rib bones, and subcutaneous fat observed during gross necropsy, most animals were judged in good to excellent condition and had 85% or more bone marrow fat.
  • Deer number 188 (1998 PZP vaccinate) had very good teeth and plenty of rumen ingesta, but she exhibited classic signs of malnutrition normally seen in deer struggling through an extremely harsh winter (poor body condition, <50% fat score, and a gelatinous bone marrow).
  • The other deer with depleted bone marrow fat, number 146 (1998 PZP treatment), and number 323 (control female), had good to excellent body condition.

3.3. Injection sites

  • Injection sites for 2000 revaccinates were compared to those for 1998 vaccinates to evaluate the persistence of dartsite lesions.
  • While abscesses were more evident and larger in 2000 revaccinates, granulomas could be found at the injection site of nearly all treated deer.

3.4. Lactation

  • Five of seven (71%) control females, and five of eight deer (63%) receiving their last vaccination in 1998 showed evidence of lactation during summer 2000 prior to the collection.
  • Three of the five (60%) lactating does were also later identified as having eosinophilic oophoritis.
  • None of the 2000 revaccinates showed evidence of lactation during necropsies.

3.5. Blood chemistry

  • There were few differences in blood chemistry between control and PZP-treated females (Table 1).
  • Some variation occurred for selected blood parameters.
  • These values fell within normal ranges and were unremarkable.

3.9. Parasites and multifocal lymphocytic infiltrates

  • One deer was found with meningeal worms (Parelaphostrongylus tenuis; no. 178, 1998 treatment group), and two had hepatic cysticerci (most likely Echinococcus granulosus; no. 55, 2000 treatment group, and no. 378, control group).
  • These animals were in good to excellent body condition.
  • Focal infiltrates and non-giant cell granulomas were seen in kidney, skeletal muscle, and liver.
  • These lesions were consistent with immune attack against migrating parasites in tissues.

4.1. Depleted bone marrow fat

  • Reduced fat content of bone marrow in PZP-treated deer was first observed by pathologists at the Cornell University College of Veterinary Medicine while conducting a necropsy on a single PZP-vaccinated deer from Irondequoit, New York [26].
  • The total sample of treated deer examined was small, and these results were not published.
  • Bone marrow fat is normally the last energy reserve used in severe cases of malnutrition during winter [25,27].
  • Even fawns confined to a restricted energy diet for 10 weeks during the fall showed no significant difference in reserves of bone marrow fat compared to fawns offered feed ad libitum during the same time period [28,29].
  • Therefore, it is very unusual to see marrow fat depleted while the deer are otherwise in good to excellent body condition.

4.2. Injection site and other abscesses

  • A variety of infectious, parasitic, and non-inflammatory lesions were described in these deer.
  • Most remarkable was the formation of granulomas at the injection site with all the characteristics of tuberculosis.
  • These granulomas were characterized by the presence of a necrotic core surrounded by mixed inflammatory cells and fibrous connective tissue.
  • Typical acid fast bacilli were documented in these giant cells and were still apparent in the lesions and lymph nodes 2 years following injections.
  • These types of inflammations, including the production of multinucleated giant cells associated with the presence of Mycobacteria in the adjuvant, have been previously described in other species vaccinated with Freund’s Complete Adjuvant [19,31–34].

4.3. Lactation

  • Residual milk, in even a completely involuted udder, is considered evidence that a doe had raised fawns during the previous summer [35,36].
  • The authors findings corroborated the Curtis et al. [7] report that five PZP-vaccinated deer delivered fawns in 2000.
  • The fact that none of the six deer revaccinated in 2000 had lactated was a result of the selection of deer receiving the revaccination, not the treatment itself.
  • The lac- tation evidence further confirms the return to normal fertility for PZP-vaccinated deer, even as some continue exhibiting oophoritis.

4.4. Histological findings

  • Ovarian inflammation resulting from PZP immunocontraceptive vaccinations have been extensively studied for many species [9–11,13,14,16–18,37–39].
  • The two most striking results from the necropsied deer were: (1) the widespread documentation of eosinophilic oophoritis in PZP-vaccinated deer, and (2) the reduced number of normal secondary follicles in females without oophoritis that were revaccinated in 2000.
  • In humans, eosinophils are inflammatory cells which develop in the bone marrow under the influence of several T-lymphocyte produced cytokines (IL-3, IL-5) [41,42].
  • They are activated by platelet-activating factor and the split products of the complement system (C5a, C3a, C4a) [43–45].
  • The eosinophils then modulated the subsequent inflammatory response in the ovary.

4.5. Anomalies

  • As for any species, reproductive anomalies can arise.
  • A small number of women experience infertility due to premature ovarian failure from autoimmune oophoritis distinguished by ovarian lymphocyte infiltrates [17,18,50].
  • The human case described by Page et al. [50] was determined to be eosinophilic perifolliculitis and tested positive for serum antiovarian antibodies.
  • Miller et al. [15] observed similar prolonged immunocontraceptive efficacy and high titers, indicating the potential for continued self-inoculation each fall as normal ovulation resumed.
  • Miller et al. [51] offered that variations in the residual immune response and physiological, morphological, or pathological differences among deer receiving identical treatments are likely due to genetic differences among individual animals from the same population.

5. Summary

  • Many factors affect the success and potential pathology associated with an immunocontraceptive vaccine, including formulation of the immunogen, concentration of the immunogen, adjuvant used, and species treated.
  • Therefore, before judgments can be made concerning the effectiveness and health risks associated with a given vaccine for a particular species, adequate evaluation must be conducted.
  • Deer vaccinated with PZP in this study continued to exhibit eosinophilic oophoritis 2 years after the last booster injection, including some deer that had already returned to normal fertility.
  • The long-term health implications resulting from the Curtis et al. [7] vaccination protocol and associated pathologies are still unknown, and further study is advisable.
  • Observation of deer with bone marrow fat depletion, at a time of year when they should have their maximum energy reserves prior to winter, is an important concern.

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Citations
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Journal ArticleDOI
TL;DR: Citation Kirkpatrick JF, Lyda RO, Frank KM.
Abstract: Wildlife, free-ranging and captive, poses and causes serious population problems not unlike those encountered with human overpopulation. Traditional lethal control programs, however, are not always legal, wise, safe, or publicly acceptable; thus, alternative approaches are necessary. Immunocontraception of free-ranging wildlife has reached the management level, with success across a large variety of species. Thus far, the immunocontraceptive research and management applications emphasis have been centered on porcine zona pellucida and gonadotropin-releasing hormone vaccines. Contraceptive success has been achieved in more than 85 different wildlife species, at the level of both the individual animal and the population. At the population management level with free-ranging species, the primary focus has been on wild horses, urban deer, bison, and African elephants. The challenges in the development and application of vaccine-based wildlife contraceptives are diverse and include differences in efficacy across species, safety of vaccines during pregnancy, the development of novel delivery systems for wild and wary free-ranging animals, and the constraints of certain non-contraceptive effects, such as effects on behavior. Beyond the constraints imposed by the public and a host of regulatory concerns, there exists a real limitation for funding of well-designed programs that apply this type of fertility control.

132 citations

Journal ArticleDOI
TL;DR: In this article, a single-injection, multi-year, GnRH contraceptive agent is needed to control reproduction in overabundant white-tailed deer populations, and two GnRH conjugates, GonaCon™ (GnRH-KLH) and gonaCon-B™ (gnRH−blue protein), were prepared in emulsion form as one-in-and twoinjection immunocontraceptive vaccine formulations.
Abstract: Problem An effective, single-injection, multi-year, GnRH contraceptive agent is needed to control reproduction in overabundant white-tailed deer populations. Method of study Two GnRH conjugates, GonaCon™ (GnRH–KLH) and GonaCon-B™ (GnRH–blue protein), were prepared in emulsion form as one-injection and two-injection immunocontraceptive vaccine formulations. In addition, the GnRH–KLH protein conjugate was lyophilized and suspended in AdjuVac™ adjuvant to produce a fifth vaccine formulation. Each formulation was administered to a group of five captive adult female white-tailed deer. Reproductive performance of treated female deer was monitored for 5 years to determine the comparative efficacy of the various treatments. Results The longevity of the contraceptive response (2–5 years) was strongly influenced by the design of the conjugate antigen, the adjuvant used, and the delivery form of the vaccine. Conclusion One-injection and two-injection formulations of GonaCon™ and GonaCon-B™ produced multi-year contraception in adult female white-tailed deer. GonaCon-B™ provided a longer lasting contraceptive effect.

100 citations

Journal ArticleDOI
TL;DR: A review of fertility control for wildlife management can be found in this paper, where the authors provide a decision tree that can be used to determine whether fertility control should be employed to resolve specific human-wildlife conflicts.
Abstract: As human populations grow, conflicts with wildlife increase. Concurrently, concerns about the welfare, safety and environmental impacts of conventional lethal methods of wildlife management restrict the options available for conflict mitigation. In parallel, there is increasing interest in using fertility control to manage wildlife. The present review aimed at analysing trends in research on fertility control for wildlife, illustrating developments in fertility-control technologies and delivery methods of fertility-control agents, summarising the conclusions of empirical and theoretical studies of fertility control applied at the population level and offering criteria to guide decisions regarding the suitability of fertility control to mitigate human–wildlife conflicts. The review highlighted a growing interest in fertility control for wildlife, underpinned by increasing numbers of scientific studies. Most current practical applications of fertility control for wild mammals use injectable single-dose immunocontraceptive vaccines mainly aimed at sterilising females, although many of these vaccines are not yet commercially available. One oral avian contraceptive, nicarbazin, is commercially available in some countries. Potential new methods of remote contraceptive delivery include bacterial ghosts, virus-like particles and genetically modified transmissible and non-transmissible organisms, although none of these have yet progressed to field testing. In parallel, new species-specific delivery systems have been developed. The results of population-level studies of fertility control indicated that this approach may increase survival and affect social and spatial behaviour of treated animals, although the effects are species- and context-specific. The present studies suggested that a substantial initial effort is generally required to reduce population growth if fertility control is the sole wildlife management method. However, several empirical and field studies have demonstrated that fertility control, particularly of isolated populations, can be successfully used to limit population growth and reduce human–wildlife conflicts. In parallel, there is growing recognition of the possible synergy between fertility control and disease vaccination to optimise the maintenance of herd immunity in the management of wildlife diseases. The review provides a decision tree that can be used to determine whether fertility control should be employed to resolve specific human–wildlife conflicts. These criteria encompass public consultation, considerations about animal welfare and feasibility, evaluation of population responses, costs and sustainability.

78 citations


Cites background from "Pathophysiology of white-tailed dee..."

  • ...Possible negative effects of ZP vaccines include speciesspecific ovarian pathology and multiple infertile oestrous cycles (in polyoestrous species), leading to extended breeding season, increasedmovements, potential late births and disruption of social hierarchy (Miller et al. 2000; Curtis et al. 2007; Kirkpatrick et al. 2009, 2011; Nuñez et al. 2009, 2010)....

    [...]

  • ...…ovarian pathology and multiple infertile oestrous cycles (in polyoestrous species), leading to extended breeding season, increasedmovements, potential late births and disruption of social hierarchy (Miller et al. 2000; Curtis et al. 2007; Kirkpatrick et al. 2009, 2011; Nuñez et al. 2009, 2010)....

    [...]

Journal ArticleDOI
TL;DR: It is concluded that long-term contraception of mustang mares with a single shot of either the SpayVac or GonaCon vaccine is possible and antibody titres against PZP and GnRH declined over the four-year study.
Abstract: We evaluated the multiyear contraceptive efficacy of the gonadotrophin-releasing hormone (GnRH) vaccine GonaCon, the porcine zona pellucida (PZP) vaccine SpayVac and the human intrauterine device (IUD) 380 Copper ‘T’ in mustang mares provided by the State of Nevada. Eight untreated control mares were compared with 12 mares treated with SpayVac, 16 mares treated with GonaCon and 15 mares treated with the copper-containing IUD. Rates of contraception for Years 1, 2, 3 and 4 respectively for SpayVac were 100% (12 of 12), 83% (10 of 12), 83% (10 of 12) and 83% (10 of 12), rates for GonaCon were 94% (15 of 16), 60% (9 of 15), 60% (9 of 15) and 40% (6 of 15) and rates for IUD-treated mares were 80% (12 of 15), 29% (4 of 14),14% (2 of 14) and 0% (0 of 14). Antibody titres against PZP and GnRH declined over the four-year study. For mares given SpayVac, uterine oedema was commonly observed. IUDs were visible by ultrasonography in non-pregnant mustang mares, suggesting that pregnant mares did not retain their IUD. IUD retention may be a function of uterine size: pony mares with IUDs had high retention and contraception rates for 4–5 years. We conclude that long-term contraception of mustang mares with a single shot of either the SpayVac or GonaCon vaccine is possible.

57 citations


Cites background from "Pathophysiology of white-tailed dee..."

  • ...…recorded for several species given PZP vaccines (Skinner et al. 1984;Mahi-Brown et al. 1988; Kirkpatrick et al. 1992; Lou et al. 1996; Stoops et al. 2006; Curtis et al. 2007), and are summarised as a disruption of folliculogenesis, depletion of primary oocytes and an infiltration of leucocytes....

    [...]

  • ...…porcine zona pellucida (PZP) vaccine (Kirkpatrick et al. 1992, 1995;Miller et al. 1999, 2001;Kirkpatrick andTurner 2002; Turner and Kirkpatrick 2002, 2003; Curtis et al. 2007) and gonadotrophin-releasing hormone (GnRH) vaccine (Miller et al. 2000, 2004; Killian et al. 2006a; Massei et al. 2008)....

    [...]

  • ...Two immunocontraceptive vaccines that have been used in a variety of species and for which data exist on their safety and efficacy are porcine zona pellucida (PZP) vaccine (Kirkpatrick et al. 1992, 1995;Miller et al. 1999, 2001;Kirkpatrick andTurner 2002; Turner and Kirkpatrick 2002, 2003; Curtis et al. 2007) and gonadotrophin-releasing hormone (GnRH) vaccine (Miller et al....

    [...]

  • ...Ovarian pathologies have been recorded for several species given PZP vaccines (Skinner et al. 1984;Mahi-Brown et al. 1988; Kirkpatrick et al. 1992; Lou et al. 1996; Stoops et al. 2006; Curtis et al. 2007), and are summarised as a disruption of folliculogenesis, depletion of primary oocytes and an infiltration of leucocytes....

    [...]

Journal ArticleDOI
TL;DR: It is concluded that more research is needed to address fundamental questions about secondary effects of contraceptive treatment and experiments are fundamental to conclusions, because researchers are missing a vital opportunity to use contraceptives as an experimental tool to test the influence of reproduction, sex and fertility on the behavior of wildlife species.
Abstract: The efficacy of contraceptive treatments has been extensively tested, and several formulations are effective at reducing fertility in a range of species. However, these formulations should minimally impact the behavior of individuals and populations before a contraceptive is used for population manipulation, but these effects have received less attention. Potential side effects have been identified theoretically and we reviewed published studies that have investigated side effects on behavior and physiology of individuals or population-level effects, which provided mixed results. Physiological side effects were most prevalent. Most studies reported a lack of secondary effects, but were usually based on qualitative data or anecdotes. A meta-analysis on quantitative studies of side effects showed that secondary effects consistently occur across all categories and all contraceptive types. This contrasts with the qualitative studies, suggesting that anecdotal reports are insufficient to investigate secondary impacts of contraceptive treatment. We conclude that more research is needed to address fundamental questions about secondary effects of contraceptive treatment and experiments are fundamental to conclusions. In addition, researchers are missing a vital opportunity to use contraceptives as an experimental tool to test the influence of reproduction, sex and fertility on the behavior of wildlife species.

40 citations


Cites background from "Pathophysiology of white-tailed dee..."

  • ...Reproduction (2010) 139 45–55 treatment (Dunbar et al. 1989, Kirkpatrick et al. 1992, Kitchener et al. 2002, Curtis et al. 2007)....

    [...]

  • ...…been reported including increased inflammation of the uterus by intrauterine devices (Daels & Hughes 1995) and alterations to ovarian function, oophoritis and cyst formation with PZP treatment (Mahi-Brown et al. 1988, Sehgal et al. 1989, Rhim et al. 1992, Stoops et al. 2006, Curtis et al. 2007)....

    [...]

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"Pathophysiology of white-tailed dee..." refers background in this paper

  • ...In October 2000, within permit authority from the New York State Department of Environmental Conservation (NYSDEC), deer were humanely killed by a shot to the head or neck from a high-powered rifle fired from a blind or a vehicle [24]....

    [...]

Frequently Asked Questions (1)
Q1. What have the authors contributed in "Pathophysiology of white-tailed deer vaccinated with porcine zona pellucida immunocontraceptive" ?

Curtis et al. this paper performed a detailed necropsy of white-tailed deer to examine potential pathological impacts resulting from a successful immunocontraceptive vaccination regimen.