Hyperimmune egg yolk antibodies developed against Clostridium perfringens antigens protect against necrotic enteritis.

Necrotic enteritis (NE) is a widespread infectious disease caused by Clostridium perfringens that inflicts major economic losses on the global poultry industry. Due to regulations on antibiotic use in poultry production, there is an urgent need for alternative strategies to mitigate the negative effects of NE. This paper presents a passive immunization technology that utilizes hyperimmune egg yolk immunoglobulin Y (IgY) specific to the major immunodominant antigens of C. perfringens. Egg yolk IgYs were generated by immunizing hens with 4 different recombinant C. perfringens antigens, and their protective effects against NE were evaluated in commercial broilers. Six different spray-dried egg powders were produced using recombinant C. perfringens antigens: α-toxin, NE B-like toxin (NetB; EB), elongation factor-Tu (ET), pyruvate:ferredoxin oxidoreductase, a mixture of 4 antigens (EM-1), and a nonimmunized control (EC). The challenged groups were either provided with different egg powders at a 1% level or no egg powders (EN). The NE challenge model based on Eimeria maxima and C. perfringens dual infection was used. In Experiments 1 and 2, the EB and ET groups exhibited increased body weight gain (BWG; P < 0.01), decreased NE lesion scores (P < 0.001), and reduced serum NetB levels (P < 0.01) compared to the EN and EC groups. IgY against NetB significantly reduced Leghorn male hepatocellular cytotoxicity in an in vitro test (P < 0.01). In Experiment 3, the protective effect of the IgYs mixture (EM-2) against C. perfringens antigens (NetB and EFTu) and Eimeria antigens (elongation factor-1-alpha: EF1α and Eimeria profilin: 3-1E) was tested. The EM-2 group showed similar body weight, BWG, and feed intake from d 7 to 22 compared to the NC group (P < 0.05). On d 20, the EM-2 group showed comparable intestinal permeability, NE lesion scores, and jejunal NetB and collagen adhesion protein levels to the NC group (P < 0.05). In conclusion, dietary mixture containing antibodies to NetB and EFTu provides protection against experimental NE in chickens through passive immunization.

Global Foot-and-Mouth Disease Research Update and Gap Analysis: 2 - Epidemiology, Wildlife and Economics.

We assessed knowledge gaps in foot-and-mouth disease (FMD) research, and in this study, we consider (i) epidemiology, (ii) wildlife and (iii) economics. The study took the form of a literature review (2011-2015) combined with research updates collected in 2014 from 33 institutes from across the world. Findings were used to identify priority areas for future FMD research. During 2011-2015, modelling studies were dominant in the broad field of epidemiology; however, continued efforts are required to develop robust models for use during outbreaks in FMD-free countries, linking epidemiologic and economics models. More guidance is needed for both the evaluation and the setting of targets for vaccine coverage, population immunity and vaccine field efficacy. Similarly, methods for seroprevalence studies need to be improved to obtain more meaningful outputs that allow comparison across studies. To inform control programmes in endemic countries, field trials assessing the effectiveness of vaccination in extensive smallholder systems should be performed to determine whether FMD can be controlled with quality vaccines in settings where implementing effective biosecurity is challenging. Studies need to go beyond measuring only vaccine effects and should extend our knowledge of the impact of FMD and increase our understanding of how to maximize farmer participation in disease control. Where wildlife reservoirs of virus exist, particularly African Buffalo, we need to better understand when and under what circumstances transmission to domestic animals occurs in order to manage this risk appropriately, considering the impact of control measures on livelihoods and wildlife. For settings where FMD eradication is unfeasible, further ground testing of commodity-based trade is recommended. A thorough review of global FMD control programmes, covering successes and failures, would be extremely valuable and could be used to guide other control programmes.

Global Foot-and-Mouth Disease Research Update and Gap Analysis: 1 - Overview of Global Status and Research Needs.

The Global Foot-and-mouth disease (FMD) Research Alliance periodically reviews the state of FMD research to assess progress and to identify new priorities. In this supplement we provide an update of global FMD research, comprising (i) this overview paper, which includes background information with key findings, and papers covering (ii) epidemiology, wildlife and economics, (iii) vaccines, (iv) diagnostics, (v) biotherapeutics and disinfectants, (vi) immunology and (vii) pathogenesis and molecular biology. FMD research publications were reviewed (2011-2015) and activity updates were obtained from 33 FMD research institutes from around the world. Although a continual threat, FMD has been effectively controlled in much of the world using existing tools. However, control remains a challenge in most developing countries, where little has been done to understand the ongoing burden of FMD. More research is needed to support control in endemically infected countries, particularly robust field studies. Traditional FMD vaccines have several limitations including short duration and spectrum of protection, cold chain requirements, and the costs and biosecurity risks associated with vaccine production. Significant progress has been made in the development of novel vaccine candidates, particularly in the use of recombinant vaccines and virus-like particles as an alternative to traditional inactivated whole virus vaccines. Continued investment is needed to turn these developments into improved vaccines produced at scale. Increased knowledge of cellular and mucosal immunity would benefit vaccine development, as would further advances in our ability to enhance vaccine capsid stability. Developments in molecular biology and phylogenetics underlie many of the recent advances in FMD research, including improved vaccines and diagnostics, and improved understanding of FMD epidemiology. Tools for genetic analyses continue to become both more powerful and more affordable enabling them to be used to address an ever-expanding range of questions. This rapidly advancing field potentiates many areas of FMD research and should be prioritized.

Global Foot-and-Mouth Disease Research Update and Gap Analysis: 5 - Biotherapeutics and Disinfectants.

We assessed knowledge gaps in foot-and-mouth disease (FMD) research. Findings are reported in a series of papers, and in this article, we consider biotherapeutics and disinfectants. The study took the form of a literature review (2011-2015) combined with research updates collected in 2014 from 33 institutes from across the world. Findings were used to identify priority areas for future FMD research. While vaccines will remain the key immunological intervention used against FMD virus (FMDV) for the foreseeable future, it takes a few days for the immune system to respond to vaccination. In an outbreak situation, protection could potentially be provided during this period by the application of rapid, short-acting biotherapeutics, aiming either to stimulate a non-specific antiviral state in the animal or to specifically inhibit a part of the viral life cycle. Certain antiviral cytokines have been shown to promote rapid protection against FMD; however, the effects of different immune-modulators appear to vary across species in ways and for reasons that are not yet understood. Major barriers to the effective incorporation of biotherapeutics into control strategies are cost, limited understanding of their effect on subsequent immune responses to vaccines and uncertainty about their potential impact if used for disease containment. Recent research has highlighted the importance of environmental contamination in FMDV transmission. Effective disinfectants for FMDV have long been available, but research is being conducted to further develop methods for quantitatively evaluating their performance under field, or near-field, conditions. During outbreaks in South Korea in 2010 there was public concern about potential environmental contamination after the mass use of disinfectant and mass burial of culled stock; this should be considered during outbreak contingency planning.

Global Foot-and-Mouth Disease Research Update and Gap Analysis: 3 - Vaccines.

This study assessed research knowledge gaps in the field of FMDV (foot-and-mouth disease virus) vaccines. The study took the form of a literature review (2011-15) combined with research updates collected in 2014 from 33 institutes from across the world. Findings were used to identify priority areas for future FMD vaccine research. Vaccines play a vital role in FMD control, used both to limit the spread of the virus during epidemics in FMD-free countries and as the mainstay of disease management in endemic regions, particularly where sanitary controls are difficult to apply. Improvements in the performance or cost-effectiveness of FMD vaccines will allow more widespread and efficient disease control. FMD vaccines have changed little in recent decades, typically produced by inactivation of whole virus, the quantity and stability of the intact viral capsids in the final preparation being key for immunogenicity. However, these are exciting times and several promising novel FMD vaccine candidates have recently been developed. This includes the first FMD vaccine licensed for manufacture and use in the USA; this adenovirus-vectored FMD vaccine causes in vivo expression of viral capsids in vaccinated animals. Another promising vaccine candidate comprises stabilized empty FMDV capsids produced in vitro in a baculovirus expression system. Recombinant technologies are also being developed to improve otherwise conventionally produced inactivated vaccines, for example, by creating a chimeric vaccine virus to increase capsid stability and by inserting sequences into the vaccine virus for desired antigen expression. Other important areas of ongoing research include enhanced adjuvants, vaccine quality control procedures and predicting vaccine protection from immune correlates, thus reducing dependency on animal challenge studies. Globally, the degree of independent vaccine evaluation is highly variable, and this is essential for vaccine quality. Previously neglected, the importance of evaluating vaccination programme effectiveness and impact is increasingly being recognized.

Global Foot-and-Mouth Disease Research Update and Gap Analysis: 6 - Immunology.

This study assessed gaps and priorities for FMDV (foot-and-mouth disease virus) research in the field of immunology. The study took the form of a literature review (2011-15) combined with research updates collected in 2014 from 33 institutes from across the world. Findings were used to identify priority areas for future FMD research. Improved understanding of FMDV immunology facilitates the development of vaccines, adjuvants and diagnostic tests, and will allow better assessment and prediction of vaccine potency and match, with reduced use of animals, particularly large animals, in experimental studies. Continued characterization of the immune systems of several FMD host species has underpinned substantial advances in knowledge of their interaction with FMDV. Recent studies have shed light on the mechanisms underlying formation of the bovine B- and T-cell response; there is also a greater understanding of the significance of non-neutralizing antibodies during FMDV infection and the interactions of antibody-bound virus with immune cells. This knowledge is directly relevant to vaccine development, as well as understanding protection and cross-protection. Despite ongoing research, significant knowledge gaps remain in the areas of neonatal and mucosal immunity. The impact of maternally derived antibody upon the neonate's ability to respond to FMD vaccination has received some attention, but few firm conclusions can be drawn at this stage, and little is known of the cellular response of young animals in general. The mucosal immune system of FMDV-susceptible species requires continued characterization, especially if the potential of mucosal vaccine-delivery systems is to be realized for FMD immunization.

Global Foot-and-Mouth Disease Research Update and Gap Analysis: 4 - Diagnostics.

This study assessed knowledge gaps in foot-and-mouth disease (FMD) research in the field of diagnostics. The study took the form of a literature review (2011-15) combined with research updates collected in 2014 from 33 institutes from around the world. Findings were used to identify priority areas for future FMD research. Molecular and genetic technologies, including sequencing, are developing at an increasing rate both in terms of capability and affordability. These advances potentiate progress in many other fields of research, from vaccine development to epidemiology. The development of RT-LAMP represents an important breakthrough allowing greater use and access to molecular diagnostics. It is now possible to determine virus serotype using PCR, although only for certain virus pools, continued progress is needed to cover the global spectrum of FMD viruses. Progress has also been made in the development of pen-side rapid diagnostics, some with the ability to determine serotype. However, further advances in pen-side serotype or strain determination would benefit both FMD-free countries and endemic countries with limited access to well-resourced laboratories. Novel sampling methods that show promise include air sampling and baited ropes, the latter may aid sampling in wildlife and swine. Studies of infrared thermography for the early detection of FMD have not been encouraging, although investigations are ongoing. Multiplex tests have been developed that are able to simultaneously screen for multiple pathogens with similar clinical signs. Crucial for assessing FMDV freedom, tests exist to detect animals that have been infected with FMDV regardless of vaccination status; however, limitations exist, particularly when testing previously vaccinated animals. Novel vaccines are being developed with complementary DIVA tests for this purpose. Research is also needed to improve the current imprecise approaches to FMD vaccine matching. The development of simple, affordable tests increases access to FMD diagnostics, greatly benefiting regions with limited laboratory capacity.

Global Foot-and-Mouth Disease Research Update and Gap Analysis: 7 - Pathogenesis and Molecular Biology.

We assessed research knowledge gaps in the fields of FMDV (foot-and-mouth disease virus) pathogenesis and molecular biology by performing a literature review (2011-15) and collecting research updates (2014) from 33 institutes from across the world. Findings were used to identify priority areas for future research. There have been important advances in FMDV pathogenesis; FMDV remains in lymph nodes of many recovered animals that otherwise do not appear persistently infected, even in species previously not associated with the carrier state. Whether virus retention helps maintain host immunity and/or virus survival is not known. Studies of FMDV pathogenesis in wildlife have provided insights into disease epidemiology, in endemic and epidemic settings. Many aspects of FMDV infection and virus entry remain unknown; however, at the cellular level, we know that expression level and availability of integrins (that permit viral entry), rate of clearance of infected cells and strength of anti-viral type I IFN (interferon) response are key determinants of tissue tropism. Extending findings to improved understanding of transmission requires a standardized approach and adoption of natural routes of infection during experimental study. There has been recognition of the importance of autophagosomes for FMDV entry into the cytoplasm following cell surface receptor binding, and that distinct internal cellular membranes are exploited for viral replication and immune evasion. New roles for viral proteins in blocking type I IFN production and downstream signalling have been identified facilitating research in anti-viral therapeutics. We know more about how infection affects cell protein expression, and research into molecular determinants of capsid stability has aided the development of stable vaccines. We have an expanding knowledge of viral and host molecular determinates of virulence and infectiousness, and of how phylogenetics may be used to estimate vaccine match and strain distribution. With ongoing advances, these areas could translate into significantly improved disease control.

Using genomics to identify novel antimicrobials.

There is a critical need in animal agriculture to develop novel antimicrobials and alternative strategies that will help to reduce the use of antibiotics and address the challenges of antimicrobial resistance. High-throughput gene expression analysis is providing new tools that are enabling the discovery of host-derived antimicrobial peptides. Examples of gene-encoded natural antibiotics that have gained attention include antimicrobial peptides such as human granulysin and its multi-species homolog, namely NK-lysin, which provide a protective response against a broad range of microbes and are a principal component of innate immunity in vertebrates. Both granulysin and NK-lysin are localised in cytolytic granules in natural killer and cytotoxic T lymphocytes. Host-derived NK-lysins that were first described in mammals are also found in avian species, and they have been shown to have antimicrobial activities that could potentially be used to control important poultry pathogens. Morphological alterations observed following chicken NK-lysin binding to Eimeria sporozoites and Escherichia coli membranes indicate damage and disruption of cell membranes, suggesting that NK-lysin kills pathogenic protozoans and bacteria by direct interaction. Genotype analysis revealed that chicken NK-lysin peptides derived from certain alleles were more effective at killing pathogens than those derived from others, which could potentially affect susceptibility to diseases. Although the host-derived antimicrobial peptides described in this paper may not, by themselves, be able to replace the antibiotics currently used in animal production, their use as specific treatments based on their known mechanisms of action is showing promising results.

Il est devenu impératif de développer de nouveaux agents antimicrobiens utilisables en production animale et de mettre au point des stratégies alternatives permettant de réduire l'utilisation des antibiotiques et de faire face aux enjeux de la résistance aux agents antimicrobiens. Les nouveaux outils rendus possibles par l'analyse à haut débit de l'expression génique permettent de découvrir les peptides antimicrobiens synthétisés par l'hôte. Parmi les antibiotiques naturels codés par des gènes qui suscitent actuellement le plus d'intérêt figurent les peptides antimicrobiens tels que la granulysine humaine et son homologue pluriespèces, la NK-lysine, qui déclenchent une réponse protectrice contre un large éventail d'agents microbiens et constituent l'une des principales composantes de l'immunité innée chez les vertébrés. La granulysine et la NK-lysine sont toutes deux localisées dans les granules cytolytiques des lymphocytes cytotoxiques T et des cellules NK (natural killer). Décrites dans un premier temps chez des mammifères, les NK-lysines synthétisées par l'hôte sont également présentes chez les oiseaux et il a été démontré qu'elles présentent des propriétés antimicrobiennes qui pourraient être utilisées pour contrôler d'importants agents pathogènes affectant les volailles. Les modifications morphologiques observées suite à la fixation de la NK-lysine du poulet aux sporozoïtes d'Eimeria et aux membranes d'Escherichia coli sont le signe d'un endommagement et d'une rupture des membranes cellulaires qui semblent indiquer que la NK-lysine tue les protozoaires et bactéries pathogènes par interaction directe. L'analyse génotypique a révélé que les peptides des NK-lysines de poulet encodés par certains allèles sont plus efficaces pour tuer les agents pathogènes que ceux encodés par d'autres allèles, ce qui pourrait avoir une influence sur la sensibilité aux maladies. Bien que les peptides antimicrobiens synthétisés par l'hôte décrits dans cet article ne puissent remplacer à eux seuls les antibiotiques utilisés actuellement en production animale, leur utilisation en tant que traitements spécifiques basés sur leurs propres mécanismes d'action connus, donne déjà des résultats prometteurs.

En el ámbito de la producción animal es ahora imperativo no solo dar con nuevos antimicrobianos, sino también concebir estrategias alternativas que ayuden a reducir el uso de antibióticos y a afrontar los problemas derivados de la resistencia a los antimicrobianos. El análisis de alto rendimiento de la expresión génica proporciona nuevas herramientas que están propiciando el descubrimiento de péptidos antimicrobianos sintetizados por los organismos anfitriones. Entre los ejemplos de antibióticos naturales codificados por genes que vienen suscitando interés están péptidos antimicrobianos como la granulisina humana y su homólogo multiespecífico, la NK-lisina, que inducen una respuesta protectora contra muy diversos microbios y son un componente básico de la inmunidad innata de los vertebrados. Tanto la granulisina como la NK-lisina están localizadas en el interior de los gránulos citolíticos de las células NK (natural killer) y los linfocitos T citotóxicos. Las NK-lisinas sintetizadas por el anfitrión, descritas en un principio en mamíferos, también se encuentran en especies aviares, y se ha demostrado que presentan propiedades antimicrobianas que podrían ser útiles para luchar contra importantes patógenos de las aves de corral. Las alteraciones morfológicas observadas después de que la NK-lisina de pollo se uniera a esporozoítos de Eimeria y a membranas de Escherichia coli son indicativas de deterioro y desorganización de la membrana celular, de donde se infiere que la NK-lisina mata a los patógenos protozoarios y bacterianos por interacción directa. El análisis genotípico en pollos reveló que ciertos alelos codificaban NK-lisinas que mataban a los patógenos con más eficacia que los péptidos codificados por otros alelos, lo que podría tener influencia en la sensibilidad a las enfermedades. Aunque tal vez los péptidos antimicrobianos sintetizados por el anfitrión que los autores describen en estas líneas no puedan, por sí solos, sustituir a los antibióticos actualmente utilizados en producción animal, su utilización en tratamientos específicos basados en sus mecanismos de acción conocidos está deparando resultados prometedores.

West Nile virus.

This review covers the basic biology of the West Nile virus and the host-vector-pathogen interactions that result in significant disease in wild birds, horses and humans. The review describes the basic properties of the virus, cellular infection and the pathogenesis of the disease, and the ecology of virus maintenance, amplification and transmission. Disease epidemiology and risk estimation strategies that are currently in use are also examined, and host immune responses and vaccination practices described. The principles of vector control, exposure control and long-term risks caused by climatic and habitat factors are also included.

Agricultural Research Service: biodefense research.

The National Animal Health Program at the Agricultural Research Service (ARS), United States Department of Agriculture (USDA), includes research programs dedicated to the defense of animal agriculture against the treat of biological agents with the potential of significant economic harm and/or public health consequences. This article provides a summary of the program and identifies its relevance to national initiatives to protect livestock and poultry as well as global food security. An introduction to setting research priorities and a selection of research accomplishments that define the scope of the biodefense research program is provided.

The future impact of animal genomics in animal health research.

The first International Symposium on Animal Genomics for Animal Health (AGAH) provided an excellent venue for scientists working in the field of genomics to interact with animal health experts. This paper provides an introduction to genome-enabled tools and highlights some of the research projects in the AGAH proceedings. A brief review of animal genomes, the next generation of genetic markers, and the versatility of genome-enabled technologies and their many applications are discussed.

Animal genomics for animal health report: critical needs, problems to be solved, potential solutions, and a roadmap for moving forward.

The first International Symposium on Animal Genomics for Animal Health, held at the World Organisation for Animal Health (OIE) Headquarter, 23-25 October, 2007, Paris, France, assembled more than 250 participants representing research organizations from 26 countries. The symposium included a roundtable discussion on critical needs, challenges and opportunities, and a forward look at the potential applications of animal genomics in animal health research. The aim of the roundtable discussion was to foster a dialogue between scientists working at the cutting edge of animal genomics research and animal health scientists. In an effort to broaden the perspective of the roundtable discussion, the organizers set out four priority areas to advance the use of genome-enabled technologies in animal health research. Contributions were obtained through open discussions and a questionnaire distributed at the start of the symposium. This symposium report provides detailed summaries ofthe outcome ofthe roundtable discussion for each of the four priority areas. For each priority, the problems needing to be solved, according to the views of the participants, are identified, including potential solutions, recommendations, and lastly, concrete steps that could be taken to address these problems. This report serves as a roadmap to steer research priorities in animal genomics research.

Genomics and vaccine development.

The current explosion in new high-throughput technologies arising from microbial and animal genomics studies is enabling the analysis of the genome, transcriptome, and proteome and offers the opportunity to gain a better understanding of the molecular pathways underlying pathogen biology, the host immune system, and host-pathogen interactions. These new tools can be applied to veterinary pathogens to overcome some of the current hurdles in the discovery of highly effective vaccines for farmed livestock and poultry.

Challenges and opportunities in developing and marketing vaccines for OIE List A and emerging animal diseases.

Veterinary pharmaceutical products generated 14.5 billion U.S. Dollars (USD) in worldwide sales in 2000, with biological products contributing 16.2 percent or 2.3 billion USD. The leading biological products were foot-and-mouth disease (FMD) vaccines, with 284 million USD in sales, representing 26.4 percent of the entire livestock biological business. Despite the potential opportunities for the biologicals industry, non-vaccination policies and undefined control and eradication strategies have deterred the private sector from significant investments in the research and development of vaccines against List A diseases. The primary research focus remains vaccines for infectious diseases that have an impact on current domestic herd health management systems. Changing the vaccine paradigm, investing in new technologies, and creating the future by integrating into key alliances with producers and regulatory authorities will be paramount in protecting our poultry and livestock industries against highly infectious diseases and potential acts of bioterrorism.

Risk analysis for the importation of veterinary biologicals into the United States of America.

International trade in veterinary biological products has been restricted by the following factors: a) concerns that contaminated products could result in the introduction of foreign animal disease agents into the importing country b) differences between countries in the technical requirements for product registration. The provisions of the North American Free Trade Agreement (NAFTA) and the General Agreement on Tariffs and Trade (GATT: now the World Trade Organisation [WTO]) require importation decisions to be science-based and transparent. This requires regulatory agencies to implement valid, credible, and science-based risk analysis models for decision-making. The Veterinary Biologics section of the United States Department of Agriculture, Animal and Plant Health Inspection Service, currently uses a formalized risk analysis model to evaluate the safety risks associated with proposals to field test and license new and biotechnology-derived veterinary biological products. This model for evaluating field tests has been modified to evaluate proposals to import veterinary biological products into the United States of America. The authors describe this risk analysis model, which was specifically designed to evaluate the risks of importing veterinary biological products potentially contaminated with foreign animal disease agents.

Confirming the safety characteristics of recombinant vectors used in veterinary medicine: a regulatory perspective.

Regulatory guidelines for experimental vaccines should encourage scientists in the biological industry to consider safety at the onset of product development. They should aid scientists to develop the necessary information to confirm conclusively the safety characteristics of the vaccine micro-organism. Moreover, these guidelines should be incorporated into a standardized regulatory process. Veterinary Biologics (VB) provides these guidelines in Summary Information Formats. These Summary Information Formats specify the relevant information to submit with a product licence application for conventional and recombinant vector vaccines. This paper compares two Summary Information Formats to demonstrate that, apart from the construction process, the information required to confirm the safety characteristics of conventional and recombinant vaccines is equivalent. A short discussion on the availability of established safety studies for experimental veterinary vaccines is included.

Current USDA procedures for licensing biotechnology-derived veterinary biologicals.

The establishment of appropriate procedures for regulating the commercialization of biotechnology products is an international issue which has been debated extensively in many countries. This paper will discuss the current procedures that have been established for the regulation of biotechnology-derived veterinary biologicals within the United States Department of Agriculture (USDA) and more specifically within Biotechnology, Biologics, and Environmental Protection (BBEP) of the Animal and Plant Health Inspection Service (APHIS). These procedures implement recent BBEP regulatory policy that has been developed to ensure risk-based regulation and avoid excessive restrictions that might curtail the development of biotechnology products.

Serum, phorbol ester, and polypeptide mitogens increase class 1 and 2 heparin-binding (acidic and basic fibroblast) growth factor gene expression in human vascular smooth muscle cells.

Vascular smooth muscle cell proliferation is regarded as a key early event in the pathogenesis of atherosclerosis. Heparin-binding growth factor (HBGF)-1 and HBGF-2, also referred to as acidic and basic fibroblast growth factor, are potent mitogens for human vascular smooth muscle cells. These cells coexpress HBGF-1 and HBGF-2 and thus represent a vessel wall source for both polypeptides. In this report, we demonstrate that HBGF-1 and HBGF-2 expression is increased when quiescent human smooth muscle cells are treated with fetal bovine serum. The kinetics of HBGF-1 and HBGF-2 mRNA accumulation following serum treatment are distinct. In addition, HBGF-1 transcripts remain elevated for a longer time period; this may reflect the different decay rates of the HBGF-1 and HBGF-2 mRNAs. Serum-inducible HBGF-1 and HBGF-2 mRNA expression does not occur when RNA synthesis is repressed by actinomycin D but can occur in the presence of cycloheximide, an inhibitor of protein synthesis. Immunoprecipitation experiments indicate that serum treatment also increases HBGF-1 and HBGF-2 production. Smooth muscle cells treated with phorbol 12-myristate 13-acetate or certain combinations of polypeptide growth factors also express increased levels of HBGF-1 and HBGF-2 transcripts. Potential sources for these growth factors in vivo include platelets, macrophages, and T lymphocytes; thus, smooth muscle cells located at sites of vascular injury or inflammation may express elevated levels of HBGF-1 and HBGF-2.