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People’s comfort with and acceptability of artificial intelligence (AI) instantiations is a topic that has received little systematic study. This is surprising given the topic’s relevance to the design, deployment and even regulation of AI systems. To help fill in our knowledge base, we conducted mixed-methods analysis based on a survey of a representative sample of the US population (N = 2254). Results show that there are two distinct social dimensions to comfort with AI: as a peer and as a superior. For both dimensions, general and technological efficacy traits—locus of control, communication apprehension, robot phobia, and perceived technology competence—are strongly associated with acceptance of AI in various roles. Female and older respondents also were less comfortable with the idea of AI agents in various roles. A qualitative analysis of comments collected from respondents complemented our statistical approach. We conclude by exploring the implications of our research for AI acceptability in society.

Cet article analyse les changements structurels découlant de l’utilisation tout à la fois généralisée et tout au long de la vie des applications de la technologie des communications mobiles. Ces changements affectent tous les secteurs de la société, y compris la sphère domestique, qui a sans doute été la plus profondément touchée. Nous discutons des développements récents et délimitons les controverses concernant la portée appropriée des interactions entre la sphère privée et la sphère publique, de la collecte des données et des services interpersonnels. Nous examinons également les phénomènes psychologiques et sociologiques résultant de leur utilisation dans les interactions humaines et sociales. Enfin, nous explorons les implications à long terme de ces changements. This article analyzes the structural changes resulting from both widespread and persistent life-course usage of mobile communication technology and its various subsidiary applications. While all sectors of society are affected by such changes, they are perhaps most perceptible in the domestic sphere. Regarding this area, we analyze contemporary issues, and most specifically to questions of the (1) scope of private-public interactions, (2) collection of data and (3) delivery of interpersonal services. Additionally, we probe the psychological and sociological phenomena resulting from persistent use of mobile communication in social interactions. Finally, we consider the longer-term implications of these changes for human relationships.

Despite several transient spikes in response to the deadliest mass shootings, the U.S. population continues to perceive gun violence as less important than other issues, and public opinion remains ...

Crowdcoding, a method that outsources “coding” tasks to numerous people on the internet, has emerged as a popular approach for annotating texts and visuals. However, the performance of this approach for analyzing social media data in the context of journalism and mass communication research has not been systematically assessed. This study evaluated the validity and efficiency of crowdcoding based on the analysis of 4,000 tweets about the 2016 U.S. presidential election. The results show that compared with the traditional quantitative content analysis, crowdcoding yielded comparably valid results and was superior in efficiency, but was more expensive under most circumstances.

Marek’s disease (MD) is a ubiquitous disease of domesticated chickens and its etiologic agent is the Gallid alphaherpesvirus 2 (GaHV-2), also known as Marek’s disease virus (MDV). MD is currently controlled by vaccination using live attenuated strains of MDV (e.g., CVI988/Rispens), non-pathogenic serotypes of MDV (GaHV-3), or non-pathogenic strains of the related Melagrid alphaherpesvirus 1 (MeHV-1). One attractive strategy for the production of new vaccine strains is a recombinant MDV attenuated by the deletion of the major viral oncogene meq. However, meq-deleted variants of MDV cause atrophy of the bursa and thymus in maternal antibody-negative chickens, and the resulting immunosuppression makes them unsuitable. Herein we detail our attempt to mitigate the lymphoid atrophy caused by meq-deleted MDV by further attenuation of the virus through ablation of the viral thymidine kinase (tk) gene. We demonstrate that ablation of the viral tk from the meq-deleted virus rMd5B40/Δmeq resulted in a virus attenuated for replication in vitro and which spared chickens from atrophy of the lymphoid organs in vivo. When the rMd5B40/Δmeq/Δtk/GFP was used as a vaccine it was protective against challenge with the vv+MDV strain 686, but the protection was less than that provided by the CVI988/Rispens vaccine.

Md5-BAC-REV-LTR is a recombinant Marek's disease virus (MDV), with an insertion of the long terminal repeat (LTR) of reticuloendotheliosis virus (REV) into the genome of the highly virulent MDV strain rMd5. It has been shown that Md5-BAC-REV-LTR does not induce tumours and confers high protection against challenge with MDV in 15 × 7 chickens. The objective of the present study was to evaluate the protection and safety (in terms of oncogenicity and immunosuppression) of Md5-BAC-REV-LTR in commercial meat-type chickens bearing maternal antibodies against MDV. Our results show that sub-cutaneous administration of Md5-BAC-REV-LTR at 1 day of age conferred high protection (protection index PI = 84.2) against an early challenge (1 day) by contact exposure to shedder birds infected with the vv+ MDV 648A strain. In such stringent challenge conditions, Md5-BAC-REV-LTR was more protective than a commercial CVI988 (PI = 12.4) and similar to the experimental vaccine Md5-BACΔmeq (PI = 92.4). Furthermore, Md5-BAC-REV-LTR did not induce either tumours or immunosuppression in this study. Immunosuppression was evaluated by the relative lymphoid organ weights and also by the ability of the vaccine to induce late-MDV-induced immunosuppression associated with reactivation of the virus. This study shows that Md5-BAC-REV-LTR has the potential to be used as a MD vaccine and is highly protective against early challenge with vv+ MDV. RESEARCH HIGHLIGHTSMd5-BAC-REV-LTR is highly protective against early challenge with vv+ MDV in commercial meat-type chickens.Md5-BAC-REV-LTR does not cause early immunosuppression.Md5-BAC-REV-LTR does not cause late immunosuppression.Unlike other serotype 1 vaccines, Md5-BAC-REV-LTR is not detected in feather pulp at 7 days post vaccination.

Education technology (Edtech) is a booming industry based on its potential to transform education and learning outcomes. With concern over remote learning, there is renewed excitement about the visual component of Edtech, namely VR, along with artificial intelligence (AI), resulting in more significant investments and innovations. Despite industrial-scale investment in Edtech's diffusion, less is known about the public's view. The public's reception of these technologies, though, maybe necessary in determining the contours of their eventual utilization. Therefore, we conducted a mixed-methods analysis based on a survey of a representative sample of the US population (N=2,254) that explores perceptions of Edtech in two instantiations: AI and VR in education. Respondents were more accepting of VR as a teaching tool than AI taking on educational roles. Assistive AI was born over AI with decision-making responsibilities. Personality and experiential traits had an influence on respondents' openness to education technologies. The results suggest support for a blended model of AI and VR use in the classroom.

Marek's disease virus (MDV) is an important poultry pathogen that is controlled through widespread vaccination with avirulent and attenuated strains. However, continued evolution of field viruses to higher virulence has required ongoing improvement of available vaccine strains, and these vaccine strains offer an attractive platform for designing recombinant vector vaccines with cross-protection against MDV and additional pathogens. Recent reports of failures in vaccine licensing trials of positive controls to reach appropriately high levels of Marek's disease incidence prompted us to evaluate possible combinations of outbred specific-pathogen-free layer lines and alternative virulent challenge strains that could provide more consistent models for serotype 3 vectored vaccine development. Choice of layer line and virulent MDV challenge strain each contributed to the ability of a challenge model to reach 80% virulence in unvaccinated positive control groups in the majority of trials, without overwhelming serotype 3 vectored vaccine protection in vaccinated groups. Conversely, reducing challenge virus dose by a factor of four, or vaccine dose by half, had no consistent effect across these models. Although MDV strain 617A had the most potential as an alternative to strains that are currently approved for licensing trials, no combination of layer line and challenge virus consistently met the goals for a successful challenge model in all study replicates, indicating that high variability is an inherent difficulty in MDV challenge studies, at least when outbred birds are used.

Artificial intelligence (AI) and robotics applications have proliferated primarily in the industrial sphere, and social scientific studies emphasized robots’ functionality and appropriateness for certain roles, especially those related to work and most particularly to robots replacing humans’ jobs. Notably, robot studies are often premised on negative prognostications, emphasizing how robots threaten livelihoods and are disruptive. As AI and robot technologies advance, however, more positive possibilities arise for robots’ social integration. However, there is an ontological divide between humans and machines that will likely influence people’s responses to and interactions with these emerging technologies. People may logically know and intend to treat robots as mere technological tools, but reflexively respond to them socially. This study explores these possible dynamics and examines how people perceive robots as social and human-like entities. A qualitative analysis of open-ended comments (N=591) collected through a survey on robot perceptions was conducted. Five main themes about social life with robots were revealed: robot as tool/machine (32.5% of comments), human-robot relationships (26.9%), social adjustment (19.0%), robot rights (10.7%), and robots’ aliveness/appearance (10.0%). The findings show that human-robot ontology is an important consideration for robots’ social acceptance and integration. AI-supported robotic technology presents great promise; however, its advancement challenges the ontological divide that has implications not only for human-machine interaction but also for self-identity and ultimately human-human relations. In terms of suggestions, these dynamics should be explored in tandem with ways to improve human-machine communication and considered from usability and design standpoints.

In the last few years, smart security and physical identification technologies have grown exponentially; people are increasingly installing smart video devices to monitor their homes and buying DNA kits to collect and analyze their genetics. As the number of users and profits of these businesses increase, so too does the potential for privacy violations and exploitation. To explore these dynamics of privacy in emerging technology, we conducted a U.S. nationally representative survey (N=1,587) and asked respondents for their perceptions of a number of emerging technologies such as facial recognition, DNA collection and biometrics monitoring. We also measured individual-level traits that have been found to influence technology acceptance. The results show that the actor wielding the technology matters for people’s acceptance. Respondents were overall more comfortable with public officials and airlines using more invasive technologies to guarantee people’s safety, as compared to private companies or non-profits using data for research. When keeping the actor constant across privacy technologies, there was an overwhelming preference for less invasive means of privacy data sharing. These findings indicate how the concept of normalization, social context and agents of control play a critical role in the way people accept emerging technology into their lives.

This chapter analyzes structural changes arising from both economy‐wide and life course-long applications of mobile communication technology. These changes trickle through all sectors of society, including the domestic sphere, which arguably has been most profoundly affected by it. The chapter highlights some ways in which people have used the mobile phone and its attendant technologies (e.g., social media) to emotional ends and speculates on what may be forthcoming as socially intelligent devices proliferate in people’s everyday lives and relationships. The authors discuss recent developments and delineate controversies concerning the appropriate scope of private and public interaction, data collection, and interpersonal services. They also examine psychological and sociological phenomena arising from their use in human life and social interactions. Finally, the authors explore the longer-term implications of these changes.

In two independent submissions, a 3-yr-old, dead Bourbon Red turkey tom from a zoo and a Royal Palm turkey hen from a backyard flock were submitted for necropsy. Both birds had been kept together with chickens. Findings of the necropsy of the first turkey were an enlarged and dark liver with many pale white foci and a few small white nodules, pale and enlarged spleen, prominent thymus, mottled and pale kidneys, and pale and enlarged testes. Findings of the necropsy of the second turkey were a dark and mildly enlarged liver and severely enlarged, firm, and pale kidneys. Histopathology revealed infiltration of most organs of both birds with neoplastic lymphocytes, which were uniform in the first turkey and pleomorphic in the second turkey. Immunohistochemistry with a CD3 marker identified the neoplastic lymphocytes as T cells. Marek's disease virus serotype 1 was detected with PCR in the livers of both birds, whereas PCRs for reticuloendotheliosis virus and lymphoproliferative disease virus were negative. Based on these findings, Marek's disease was diagnosed in both turkeys, which is very rare and were the first definitive cases reported in the United States. It is likely that the chickens were the source of infection.

People around the world who seek to interact with large organisations increasingly find they must do so via mediated and automated communication. Organisations often deploy both mediated and automated platforms, such as instant messaging and interactive voice response systems (IVRs), for efficiency and cost-savings. Customer and client responses to these systems range from delight to frustration. To better understand the factors affecting people's satisfaction with these systems, we conducted a representative U.S. national survey (N = 1321). We found that people overwhelmingly like and trust in-person customer service compared to mediated and automated modalities. As to demographic attitude predictors, age was important (older respondents liked mediated systems less), but income and education were not strong attitude predictors. For personality variables, innovativeness was positively associated with mediated system satisfaction. However, communication apprehensiveness, which we expected to be related to satisfaction, was not. We conclude by discussing implications for the burgeoning field of human-machine communication, as well as social policy, equity, and the pullulating digital services divide.

Many livestock and human vaccines are leaky because they block symptoms but do not prevent infection or onward transmission. This leakiness is concerning because it increases vaccination coverage required to prevent disease spread and can promote evolution of increased pathogen virulence. Despite leakiness, vaccination may reduce pathogen load, affecting disease transmission dynamics. However, the impacts on post-transmission disease development and infectiousness in contact individuals are unknown. Here, we use transmission experiments involving Marek disease virus (MDV) in chickens to show that vaccination with a leaky vaccine substantially reduces viral load in both vaccinated individuals and unvaccinated contact individuals they infect. Consequently, contact birds are less likely to develop disease symptoms or die, show less severe symptoms, and shed less infectious virus themselves, when infected by vaccinated birds. These results highlight that even partial vaccination with a leaky vaccine can have unforeseen positive consequences in controlling the spread and symptoms of disease., "Leaky" vaccination of chickens infected with Marek“s disease virus reduced symptoms and lowered mortality in the unvaccinated contact birds infected by them. The cause was transmission of lower virus loads from vaccinated than unvaccinated birds; this benefit of leaky vaccination is rarely taken into consideration.

Lymphoid leukosis (LL)-like lymphoma is a low-incidence yet costly and poorly understood disease of domestic chickens. The observed unique characteristics of LL-like lymphomas are that the incidence of the disease is chicken line dependent; pathologically, it appeared to mimic avian leukosis but is free of exogenous ALV infection; inoculation of the nonpathogenic ALV-E or MDV-2 (SB-1) boosts the incidence of the disease; and inoculation of both the nonpathogenic ALV-E and SB-1 escalates it to much higher levels. This study was designed to test the impact of two new ALV-E isolates, recently derived from commercial broiler breeder flocks, in combination with the nonpathogenic SB-1 on LL-like lymphoma incidences in both an experimental egg layer line of chickens and a commercial broiler breeder line of chickens under a controlled condition. Data from this study provided an additional piece of experimental evidence on the potency of nonpathogenic ALV-E, MDV-2, and ALV-E plus MDV-2 in boosting the incidence of LL-like lymphomas in susceptible chickens. This study also generated the first piece of genomic evidence that suggests host transcriptomic variation plays an important role in modulating LL-like lymphoma formation., In 2010, sporadic cases of avian leukosis virus (ALV)-like bursal lymphoma, also known as spontaneous lymphoid leukosis (LL)-like tumors, were identified in two commercial broiler breeder flocks in the absence of exogenous ALV infection. Two individual ALV subgroup E (ALV-E) field strains, designated AF227 and AF229, were isolated from two different breeder farms. The role of these ALV-E field isolates in development of and the potential joint impact in conjunction with a Marek’s disease virus (MDV) vaccine (SB-1) were further characterized in chickens of an experimental line and commercial broiler breeders. The experimental line 0.TVB*S1, commonly known as the rapid feathering-susceptible (RFS) line, of chickens lacks all endogenous ALV and is fully susceptible to all subgroups of ALV, including ALV-E. Spontaneous LL-like tumors occurred following infection with AF227, AF229, and a reference ALV-E strain, RAV60, in RFS chickens. Vaccination with serotype 2 MDV, SB-1, in addition to AF227 or AF229 inoculation, significantly enhanced the spontaneous LL-like tumor incidence in the RFS chickens. The spontaneous LL-like tumor incidence jumped from 14% by AF227 alone to 42 to 43% by AF227 in combination with SB-1 in the RFS chickens under controlled conditions. RNA-sequencing analysis of the LL-like lymphomas and nonmalignant bursa tissues of the RFS line of birds identified hundreds of differentially expressed genes that are reportedly involved in key biological processes and pathways, including signaling and signal transduction pathways. The data from this study suggested that both ALV-E and MDV-2 play an important role in enhancement of the spontaneous LL-like tumors in susceptible chickens. The underlying mechanism may be complex and involved in many chicken genes and pathways, including signal transduction pathways and immune system processes, in addition to reported viral genes. IMPORTANCE Lymphoid leukosis (LL)-like lymphoma is a low-incidence yet costly and poorly understood disease of domestic chickens. The observed unique characteristics of LL-like lymphomas are that the incidence of the disease is chicken line dependent; pathologically, it appeared to mimic avian leukosis but is free of exogenous ALV infection; inoculation of the nonpathogenic ALV-E or MDV-2 (SB-1) boosts the incidence of the disease; and inoculation of both the nonpathogenic ALV-E and SB-1 escalates it to much higher levels. This study was designed to test the impact of two new ALV-E isolates, recently derived from commercial broiler breeder flocks, in combination with the nonpathogenic SB-1 on LL-like lymphoma incidences in both an experimental egg layer line of chickens and a commercial broiler breeder line of chickens under a controlled condition. Data from this study provided an additional piece of experimental evidence on the potency of nonpathogenic ALV-E, MDV-2, and ALV-E plus MDV-2 in boosting the incidence of LL-like lymphomas in susceptible chickens. This study also generated the first piece of genomic evidence that suggests host transcriptomic variation plays an important role in modulating LL-like lymphoma formation.

The South China Sea dispute is one of the most complicated geopolitical issues of the twenty-first century. While this international conflict revolves around military and economic disputes, in toda...

An adolescent girl explores the notion of freedom as she navigates her abusive home life. The story, which takes place on both sides of the El Paso-Juarez border in the 1970s, also examines racial tensions and the differing viewpoints between generations.

The volume’s introduction locates the current digital dimension of “fake news” phenomenon in the nascent days of the Internet and broadly discusses the issues with information online and the often frustrating pursuit of truth in that context. Given the vast topic of truth in journalism, the chapter outlines the selective inquiries the book makes to bridge discussions of digital disruption in journalism. Precipitated by social media technologies, it probes deeper questions about truth and objectivity in journalism. It discusses several key approaches to truth in journalism that may be taken, and then reviews different perspectives on “news”—practitioner’s, democratic, sociological, psychological, economic, and political views. The introduction next previews the volume’s contents, organized under the main themes of “democracy, news, and society,” “pillars of truth in journalism,” the “craft of journalism,” and “reception and perception” of news, and closes with a description of how the volume treats its tripartite prongs of politics, truth, and technology.

The book concludes with a summary of the various perspectives presented throughout the chapters and the trends emerging from the practitioner lessons that each chapter provides for journalists in the age of social media. The chapter considers what is old and what is new with social media and journalism through the three lenses that have guided the book’s contents: politics, truth, and technology. The conclusion finishes with some forward-looking thoughts on how technology may evolve and adapt for people’s needs to be civically and politically engaged online, but not consumed by the ever-growing mountain of causes and outrages that necessarily proliferate given the nature of the technological environment, but perhaps needlessly overwhelm, excite, and enrage to the point of distraction and cognitive overload.

Different news articles about the same topic often offer a variety of perspectives: an article written about gun violence might emphasize gun control, while another might promote 2nd Amendment rights, and yet a third might focus on mental health issues. In communication research, these different perspectives are known as “frames”, which, when used in news media will influence the opinion of their readers in multiple ways. In this paper, we present a method for effectively detecting frames in news headlines. Our training and performance evaluation is based on a new dataset of news headlines related to the issue of gun violence in the United States. This Gun Violence Frame Corpus (GVFC) was curated and annotated by journalism and communication experts. Our proposed approach sets a new state-of-the-art performance for multiclass news frame detection, significantly outperforming a recent baseline by 35.9% absolute difference in accuracy. We apply our frame detection approach in a large scale study of 88k news headlines about the coverage of gun violence in the U.S. between 2016 and 2018.

Marek’s disease virus (MDV), an alphaherpesvirus, causes Marek’s disease (MD), a lymphoproliferative disease in poultry characterized by T-cell lymphomas, nerve lesions, and mortality. Vaccination is used worldwide to control MD, but increasingly virulent field strains can overcome this protection, driving a need to create new vaccines. Previous studies revealed that insertion of reticuloendotheliosis virus (REV) long terminal repeat (LTR) into a bacterial artificial chromosome (BAC) clone of a very virulent strain of MDV, Md5, rendered the resultant recombinant virus, rMd5 REV-LTR BAC, fully attenuated in maternal antibody positive (Mab+) chickens at passage 40. In the current study, the protective efficacy of rMd5 REV-LTR BAC was evaluated. First, passage 70 was identified as being fully attenuated in maternal antibody negative chickens and chosen as the optimal passage level for use in protective efficacy studies. Second, three protective efficacy trials were conducted comparing the rMd5 REV-LTR p70 BAC to the CVI988/Rispens vaccine. Groups of Mab+ and Mab− 15I5 × 71 chickens were vaccinated in ovo at 18 days of embryonation or intra-abdominally at day of hatch, and challenged at 5 days post-hatch with the vv+MDV strain 686. Vaccination at day of hatch and in ovo with rMd5 REV-LTR p70 BAC protected chickens against MDV-induced bursa and thymic atrophy, but did not provide the same level of protection against MD tumours as that afforded by the commercial vaccine, CVI988/Rispens.

A variety of techniques have been developed as diagnostic tools for the differential diagnosis of tumours produced by Marek's disease virus from those induced by avian leukosis virus and reticuloendotheliosis virus. However, most current techniques are unreliable when used in formalin-fixed paraffin-embedded (FFPE) tissues, which often is the only sample type available for definitive diagnosis. A collection of tumours was generated by the inoculation of different strains of Marek's disease virus, reticuloendotheliosis virus or avian leukosis virus singularly or in combination. FFPE tissue sections from tumour and non-tumour tissues were analysed by optimized immunohistochemistry (IHC) techniques and traditional as well as quantitative polymerase chain reaction (PCR) with newly designed primers ideal for DNA fragmented by fixation. IHC and PCR results were highly sensitive and specific in tissues from single-infected birds. Virus quantity was higher in tumours compared to non-tumour spleens from Marek's disease (MD) virus-infected birds. Thus, using FFPE sections alone may be sufficient for the diagnosis of MD by demonstration of high quantities of viral antigens or genome in tumour cells, along with the absence of other tumour viruses by traditional PCR, and if standard criteria are met based on clinical history and histology. IHC furthermore allowed detection of the specific cells that were infected with different viruses in tumours from birds that had been inoculated simultaneously with multiple viruses. Following validation with field samples, these new protocols can be applied for both diagnostic and research purposes to help accurately identify avian tumour viruses in routine FFPE tissue sections.

Urban environments are the primary contributors to global anthropogenic carbon emissions. Because much of the growth in CO2 emissions will originate from cities, there is a need to develop, assess, and improve measurement and modeling strategies for quantifying and monitoring greenhouse gas emissions from large urban centers. In this study the uncertainties in an aircraft-based mass balance approach for quantifying carbon dioxide and methane emissions from an urban environment, focusing on Indianapolis, IN, USA, are described. The relatively level terrain of Indianapolis facilitated the application of mean wind fields in the mass balance approach. We investigate the uncertainties in our aircraft-based mass balance approach by (1) assessing the sensitivity of the measured flux to important measurement and analysis parameters including wind speed, background CO2 and CH4, boundary layer depth, and interpolation technique, and (2) determining the flux at two or more downwind distances from a point or area source (with relatively large source strengths such as solid waste facilities and a power generating station) in rapid succession, assuming that the emission flux is constant. When we quantify the precision in the approach by comparing the estimated emissions derived from measurements at two or more downwind distances from an area or point source, we find that the minimum and maximum repeatability were 12 and 52%, with an average of 31%. We suggest that improvements in the experimental design can be achieved by careful determination of the background concentration, monitoring the evolution of the boundary layer through the measurement period, and increasing the number of downwind horizontal transect measurements at multiple altitudes within the boundary layer.

SUMMARY A simple PCR method was developed for the detection of Marek's disease (MD) and reticuloendotheliosis (RE) in formalin-fixed paraffin-embedded (FFPE) tissues, and for the detection of MD in tissues only preserved in 10% neutral buffered formalin. MD virus (MDV) and RE virus proviral DNA were detected in FFPE tissues stored for over 20 yr. MDV was also detected in tissues only preserved in formalin for up to 6 mo. The data indicate that PCR of formalin-fixed and FFPE tissues is a simple and valuable tool that can be used to identify MD and RE infection. The method described in this paper is a good alternative to any biologic or immunohistochemical assay to confirm the detection of MD and RE, as it does not require shipping frozen tissues to the diagnostic laboratory.

Co-cultivation of the JM/102W strain of Marek's disease virus (MDV) with reticuloendotheliosis virus (REV) resulted in the generation of a recombinant MDV containing the REV long terminal repeat (LTR) named the RM1 strain of MDV, a strain that was highly attenuated for oncogenicity but induced severe bursal and thymic atrophy. We hypothesize that the phenotypic changes were solely due to the LTR insertion. Furthermore, we hypothesize that insertion of REV LTR into an analogous location in a different MDV would result in a similar phenotypic change. To test these hypotheses, we inserted the REV LTR into a bacterial artificial chromosome (BAC) clone of a very virulent strain of MDV, Md5, and designated the virus rMd5-RM1-LTR. The rMd5-RM1-LTR virus and the rMd5 virus were passaged in duck embryo fibroblast cells for up to 40 passages before pathogenicity studies. Susceptible chickens were inoculated intra-abdominally at hatch with the viruses rMd5-RM1-LTR, rMd5 BAC parental virus, wild-type strain Md5, or strain RM1 of MDV. The rMd5-RM1-LTR virus was attenuated at cell culture passage 40, whereas the rMd5 BAC without RM1 LTR retained its pathogenicity at cell culture passage 40. Using polymerase chain analysis, the RM1 LTR insert was detected in MDV isolated from buffy coat cells collected from chickens inoculated with rMd5-RM1-LTR, but only at 1 week post inoculation. The data suggest that the presence of the RM1 LTR insert within MDV genome for 1 week post inoculation with virus at hatch is sufficient to cause a reduction in pathogenicity of strain Md5 of MDV.