Ongoing declines for the world's amphibians in the face of emerging threats

Systematic assessments of species extinction risk at regular intervals are necessary for informing conservation action1,2. Ongoing developments in taxonomy, threatening processes and research further underscore the need for reassessment3,4. Here we report the findings of the second Global Amphibian Assessment, evaluating 8,011 species for the International Union for Conservation of Nature Red List of Threatened Species. We find that amphibians are the most threatened vertebrate class (40.7% of species are globally threatened). The updated Red List Index shows that the status of amphibians is deteriorating globally, particularly for salamanders and in the Neotropics. Disease and habitat loss drove 91% of status deteriorations between 1980 and 2004. Ongoing and projected climate change effects are now of increasing concern, driving 39% of status deteriorations since 2004, followed by habitat loss (37%). Although signs of species recoveries incentivize immediate conservation action, scaled-up investment is urgently needed to reverse the current trends.

Conservation resource allocation, small population resiliency, and the fallacy of conservation triage

Some conservation prioritization methods are based on the assumption that conservation needs overwhelm current resources and not all species can be conserved; therefore, a conservation triage scheme (i.e., when the system is overwhelmed, species should be divided into three groups based on likelihood of survival, and efforts should be focused on those species in the group with the best survival prospects and reduced or denied to those in the group with no survival prospects and to those in the group not needing special efforts for their conservation) is necessary to guide resource allocation. We argue that this decision-making strategy is not appropriate because resources are not as limited as often assumed, and it is not evident that there are species that cannot be conserved. Small population size alone, for example, does not doom a species to extinction; plants, reptiles, birds, and mammals offer examples. Although resources dedicated to conserving all threatened species are insufficient at present, the world's economic resources are vast, and greater resources could be dedicated toward species conservation. The political framework for species conservation has improved, with initiatives such as the UN Sustainable Development Goals and other international agreements, funding mechanisms such as The Global Environment Facility, and the rise of many nongovernmental organizations with nimble, rapid-response small grants programs. For a prioritization system to allow no extinctions, zero extinctions must be an explicit goal of the system. Extinction is not inevitable, and should not be acceptable. A goal of no human-induced extinctions is imperative given the irreversibility of species loss.

Using the 2020 global pandemic as a springboard to highlight the need for amphibian conservation in eastern Asia

Emerging infectious diseases are on the rise in many different taxa, including, among others, the amphibian batrachochytrids, the snake fungal disease and the Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) virus, responsible for Coronavirus disease 2019 (COVID-19) in mammals. Following the onset of the pandemic linked to COVID-19, eastern Asia has shown strong leadership, taking actions to regulate the trade of potential vector species in several regions. These actions were taken in response to an increase in public awareness, and the need for a quick reaction to mitigate against further pandemics. However, trade restrictions rarely affect amphibians, despite the risk of pathogen transmission, directly, or indirectly through habitat destruction and the loss of vector consumption. Thus, species that help alleviate the risk of zoonoses or provide biological control are not protected. Hence, in view of the global amphibian decline and the risk of zoonoses, we support the current wildlife trade regulations and support measures to safeguard wildlife from overexploitation. The current period of regulation overhaul should be used as a springboard for amphibian conservation. To mitigate risks, we suggest the following stipulations specifically for amphibians. I) Restrictions to amphibian farming in eastern Asia, in relation to pathogen transmission and the establishment of invasive species. II) Regulation of the amphibian pet trade, with a focus on potential vector species. III) Expansion of the wildlife trade ban, to limit the wildlife-human-pet interface. The resulting actions will benefit both human and wildlife populations, as they will lead to a decrease in the risk of zoonoses and better protection of the environment.

SIGNIFICANCE STATEMENT

There is an increasing number of emerging infectious diseases impacting all species, including amphibians, reptiles and mammals. The latest threat to humans is the virus responsible for COVID-19, and the resulting pandemic. Countries in eastern Asia have taken steps to regulate wildlife trade and prevent further zoonoses thereby decreasing the risk of pathogens arising from wild species. However, as amphibians are generally excluded from regulations we support specific trade restrictions: I) Restrictions to amphibian farming; II) regulation of the amphibian pet trade; III) expansion of the wildlife trade ban. These restrictions will benefit both human and wildlife populations by decreasing the risks of zoonoses and better protecting the environment.

The evolutionary history of the goby Elacatinus puncticulatus in the tropical eastern pacific: Effects of habitat discontinuities and local environmental variability

Habitat discontinuities, temperature gradients, upwelling systems, and ocean currents, gyres and fronts, can affect distributions of species with narrow environmental tolerance or motility and influence the dispersal of pelagic larvae, with effects ranging from the isolation of adjacent populations to connections between them. The coast of the Tropical Eastern Pacific (TEP) is a highly dynamic environment, with various large gyres and upwelling systems, alternating currents and large rocky-habitat discontinuities, which may greatly influence the genetic connectivity of populations in different parts of the coast. Elacatinus puncticulatus is a cryptic, shallow-living goby that is distributed along the continental shore of virtually the entire TEP, which makes it a good model for testing the influence of these environmental characteristics in the molecular evolution of widespread species in this region. A multilocus phylogeny was used to evaluate the influence of habitat gaps, and oceanographic processes in the evolutionary history of E. puncticulatus throughout its geographical range in the TEP. Two well-supported allopatric clades (one with two allopatric subclades) were recovered, the geographic distribution of which does not correspond to any previously proposed major biogeographic provinces. These populations show strong genetic structure and substantial genetic distances between clades and sub-clades (cytb 0.8-7.3%), with divergence times between them ranging from 0.53 to 4.88 Mya, and recent population expansions dated at 170-130 Kya. The ancestral area of all populations appears to be the Gulf of Panama, while several isolation events have formed the phylogeographic patterns evident in this species. Local and regional oceanographic processes as well as habitat discontinuities have shaped the distribution patterns of the genetic lineages along the continental TEP. Large genetic distances, high genetic differentiation, and the results of species-tree and phylogenetic analyses indicate that E. puncticulatus comprises a complex of three allopatric species with an unusual geographic arrangement.

A new species of Astyanax (Characiformes: Characidae) from Costa Rica and Panama, with a key to the lower Central American species of the genus

Astyanax anai, a new species of characid fish, is described from the Sixaola River basin, eastern Costa Rica-western Panama, Central America. The new species can be distinguished from all other congeners by the following combination of characters: premaxillary teeth 4-5 at the inner series and 4-6 at the outer series; maxillary teeth tricuspid, 2-4; predorsal scale series irregular and incomplete, with an unscaled space behind tip of supraoccipital process and 12-14 scales; lateral line scales 34-39; humeral region with a conspicuous black and rounded to horizontally ovate spot and two diffuse brown and vertically elongate bars (the first through the rounded to horizontally ovate spot, the second 2-4 scales behind the first); body depth 36·6-42·3% of standard length (L_S ); midlateral stripe formed by a series of 10-14 anteriorly-directed dermal herringbone, or chevron-shaped, marks, most apparent in juveniles and in preserved specimens, extending above the lateral line from the black humeral spot or just behind it (from the second vertical bar) to the caudal peduncle; scale rows from lateral line to base of first dorsal-fin ray 8-9; scale rows from lateral line to base of pelvic fin 7-8; pre-anal distance 53·9-61·9% of L_S ; total anal-fin elements 29-33; caudal spot elongated, rhomboid or rectangular, with its anterior margin surpassing the middle of the caudal peduncle, usually reaching the anal-fin insertion, posteriorly covering 4-7 principal caudal-fin rays and not extending onto the ventral and dorsal margins of the caudal peduncle, covering 3-5 horizontal scale rows. In order to test the phylogenetic relationships of the new taxon in relation to the other North and Central American species of the genus, a new phylogenetic hypothesis based on a reanalysis of the morphological matrix by Schmitter-Soto (2016) is proposed. A key to the lower Central American (southern Nicaragua to eastern Panama) species of Astyanax is also provided.

Psychological impact of multigene cancer panel testing in patients with a clinical suspicion of hereditary cancer across Spain

OBJECTIVE

Patients' psychological reactions to multigene cancer panel testing might differ compared with the single-gene testing reactions because of the complexity and uncertainty associated with the different possible results. Understanding patients' preferences and psychological impact of multigene panel testing is important to adapt the genetic counselling model.

METHODS

One hundred eighty-seven unrelated patients with clinical suspicion of hereditary cancer undergoing a 25-gene panel test completed questionnaires after pretest genetic counselling and at 1 week, 3 months, and 12 months after results to elicit their preferences regarding results disclosure and to measure their cancer worry and testing-specific distress and uncertainty.

RESULTS

A pathogenic variant was identified in 38 patients (34 high penetrance and 4 moderate penetrance variants), and 54 patients had at least one variant of uncertain significance. Overall, cancer panel testing was not associated with an increase in cancer worry after results disclosure (P value = .87). Twelve months after results, carriers of a moderate penetrance variant had higher distress and uncertainty scores compared with carriers of high penetrance variants. Cancer worry prior to genetic testing predicted genetic testing specific distress after results, especially at long term (P value <.001). Most of the patients reported the wish to know all genetic results.

CONCLUSIONS

Our results suggest that patients can psychologically cope with cancer panel testing, but distress and uncertainty observed in carriers of moderate penetrance cancer variants in this cohort warrant further research.

Assessing the Cost of Global Biodiversity and Conservation Knowledge

Knowledge products comprise assessments of authoritative information supported by standards, governance, quality control, data, tools, and capacity building mechanisms. Considerable resources are dedicated to developing and maintaining knowledge products for biodiversity conservation, and they are widely used to inform policy and advise decision makers and practitioners. However, the financial cost of delivering this information is largely undocumented. We evaluated the costs and funding sources for developing and maintaining four global biodiversity and conservation knowledge products: The IUCN Red List of Threatened Species, the IUCN Red List of Ecosystems, Protected Planet, and the World Database of Key Biodiversity Areas. These are secondary data sets, built on primary data collected by extensive networks of expert contributors worldwide. We estimate that US$160 million (range: US$116–204 million), plus 293 person-years of volunteer time (range: 278–308 person-years) valued at US$ 14 million (range US$12–16 million), were invested in these four knowledge products between 1979 and 2013. More than half of this financing was provided through philanthropy, and nearly three-quarters was spent on personnel costs. The estimated annual cost of maintaining data and platforms for three of these knowledge products (excluding the IUCN Red List of Ecosystems for which annual costs were not possible to estimate for 2013) is US$6.5 million in total (range: US$6.2–6.7 million). We estimated that an additional US$114 million will be needed to reach pre-defined baselines of data coverage for all the four knowledge products, and that once achieved, annual maintenance costs will be approximately US$12 million. These costs are much lower than those to maintain many other, similarly important, global knowledge products. Ensuring that biodiversity and conservation knowledge products are sufficiently up to date, comprehensive and accurate is fundamental to inform decision-making for biodiversity conservation and sustainable development. Thus, the development and implementation of plans for sustainable long-term financing for them is critical.

Notes on range extension and geographic variation of calls in Adenomera thomei (Anura: Leptodactylidae)

New localities are herein reported for Adenomera thomei in Minas Gerais state, increasing its known distribution towards the Brazilian northwest and expanding knowledge on its habitat use. The advertisement calls of Adenomera thomei here reported exhibit variation in the call parameters known for this species, but also reveal a degree of overlap with the calls of a closely related undescribed species, suggesting that further research is needed to elucidate geographic call variation and population identities.

Investigating fusion plasma instabilities in the Mega Amp Spherical Tokamak using mega electron volt proton emissions (invited)

The proton detector (PD) measures 3 MeV proton yield distributions from deuterium-deuterium fusion reactions within the Mega Amp Spherical Tokamak (MAST). The PD's compact four-channel system of collimated and individually oriented silicon detectors probes different regions of the plasma, detecting protons (with gyro radii large enough to be unconfined) leaving the plasma on curved trajectories during neutral beam injection. From first PD data obtained during plasma operation in 2013, proton production rates (up to several hundred kHz and 1 ms time resolution) during sawtooth events were compared to the corresponding MAST neutron camera data. Fitted proton emission profiles in the poloidal plane demonstrate the capabilities of this new system.

Identifying the world's most climate change vulnerable species: a systematic trait-based assessment of all birds, amphibians and corals

Climate change will have far-reaching impacts on biodiversity, including increasing extinction rates. Current approaches to quantifying such impacts focus on measuring exposure to climatic change and largely ignore the biological differences between species that may significantly increase or reduce their vulnerability. To address this, we present a framework for assessing three dimensions of climate change vulnerability, namely sensitivity, exposure and adaptive capacity; this draws on species' biological traits and their modeled exposure to projected climatic changes. In the largest such assessment to date, we applied this approach to each of the world's birds, amphibians and corals (16,857 species). The resulting assessments identify the species with greatest relative vulnerability to climate change and the geographic areas in which they are concentrated, including the Amazon basin for amphibians and birds, and the central Indo-west Pacific (Coral Triangle) for corals. We found that high concentration areas for species with traits conferring highest sensitivity and lowest adaptive capacity differ from those of highly exposed species, and we identify areas where exposure-based assessments alone may over or under-estimate climate change impacts. We found that 608-851 bird (6-9%), 670-933 amphibian (11-15%), and 47-73 coral species (6-9%) are both highly climate change vulnerable and already threatened with extinction on the IUCN Red List. The remaining highly climate change vulnerable species represent new priorities for conservation. Fewer species are highly climate change vulnerable under lower IPCC SRES emissions scenarios, indicating that reducing greenhouse emissions will reduce climate change driven extinctions. Our study answers the growing call for a more biologically and ecologically inclusive approach to assessing climate change vulnerability. By facilitating independent assessment of the three dimensions of climate change vulnerability, our approach can be used to devise species and area-specific conservation interventions and indices. The priorities we identify will strengthen global strategies to mitigate climate change impacts.

The impact of conservation on the status of the world's vertebrates

Using data for 25,780 species categorized on the International Union for Conservation of Nature Red List, we present an assessment of the status of the world's vertebrates. One-fifth of species are classified as Threatened, and we show that this figure is increasing: On average, 52 species of mammals, birds, and amphibians move one category closer to extinction each year. However, this overall pattern conceals the impact of conservation successes, and we show that the rate of deterioration would have been at least one-fifth again as much in the absence of these. Nonetheless, current conservation efforts remain insufficient to offset the main drivers of biodiversity loss in these groups: agricultural expansion, logging, overexploitation, and invasive alien species.

Antibacterial and free-radical scavenging activities of Sonoran propolis

AIMS

To evaluate the antibacterial and free-radical scavenging (FRS) activities of propolis collected from three different areas of Sonoran Desert in northwestern Mexico [Pueblo de Alamos (PAP), Ures (UP) and Caborca (CP)].

METHODS AND RESULTS

The antibacterial and FRS activities of Sonoran propolis were determined by the broth microdilution method and the DPPH (1,1-diphenyl-2-picrylhydracyl) assay, respectively. Propolis samples had antibacterial activity against only Gram-positive bacteria. The UP sample showed the highest antibacterial activity against Staphylococcus aureus [minimal inhibitory concentration (MIC) 100 microg ml(-1)] in a concentration-dependent manner (UP > CP > PAP). Caffeic acid phenethyl ester (CAPE), a UP propolis constituent, had very high growth-inhibitory activity towards Gram-positive bacteria, particularly against S. aureus (MIC 0.1 mmol l(-1)). To our knowledge, this is the first study showing a strong antibacterial activity of CAPE against S. aureus. Additionally, propolis CP exhibited high FRS activity (86% +/- 0.3 at 100 microg ml(-1)) comparable with those of the reference antioxidants vitamin C (87.4% +/- 1.7 at 70 micromol l(-1)) and BHT (66.07% +/- 0.76 at 140 micromol l(-1)). The propolis compounds CAPE and rutin showed high FRS activity (90.4% +/- 0.2 and 88.5% +/- 0.8 at 70 micromol l(-1), respectively).

CONCLUSIONS

Sonoran propolis UP and CAPE had strong antibacterial activity against S. aureus. In addition, propolis CP showed potent FRS activity comparable with those of vitamin C and BHT.

SIGNIFICANCE AND IMPACT OF THE STUDY

The strong antibacterial and antioxidant properties of Sonoran propolis and some of its constituents support further studies on the clinical applications of this natural bee product against S. aureus and several oxidative damage-related diseases.

NK cell receptors involved in the response to human cytomegalovirus infection

Human cytomegalovirus (HCMV) infection is a paradigm of the complexity reached by host-pathogen interactions. To avoid recognition by cytotoxic T lymphocytes (CTL) HCMV inhibits the expression of HLA class I molecules. As a consequence, engagement of inhibitory killer immunoglobulin-like receptors (KIR), CD94/NKG2A, and CD85j (ILT2 or LIR-1) natural killer cell receptors (NKR) specific for HLA class I molecules is impaired, and infected cells become vulnerable to an NK cell response driven by activating receptors. In addition to the well-defined role of the NKG2D lectin-like molecule, the involvement of other triggering receptors (i.e., activating KIR, CD94/NKG2C, NKp46, NKp44, and NKp30) in the response to HCMV is being explored. To escape from NK cell-mediated surveillance, HCMV interferes with the expression of NKG2D ligands in infected cells. In addition, the virus may keep NK inhibitory receptors engaged preserving HLA class I molecules with a limited role in antigen presentation (i.e., HLA-E) or, alternatively, displaying class I surrogates. Despite considerable progress in the field, a number of issues regarding the involvement of NKR in the innate immune response to HCMV remain uncertain.

Progressive hepatocytic fatty infiltration in rats with prehepatic portal hypertension

BACKGROUND/AIMS

Homogenous evolution, with a narrow range of portal hypertension, degree of portosystemic shunt and hepatic atrophy has been described in the experimental model of prehepatic portal hypertension in the rat. However the great differences observed in the rats' liver weight could be attributed to a pathological alteration of the liver. Based on this, we performed an evolutive histological study of the liver. This study shows the existence of a progressive hepatocytic fatty infiltration.

METHODOLOGY

Male Wistar rats with portal hypertension induced by triple stenosing ligation of the portal vein at 1 month (group II, n=4) and at 1 year (group IV, n=10) of postoperative evolution were used. The portal pressure, body, liver and splenic weights, types of collateral circulation and degree of mesenteric venous congestion were studied. The intracytoplasmatic lipid microvacuoles were quantified in hepatocytes with an image analyzer (software MIP/CID, Spain). The results were compared with those obtained in control rats with the same evolutive periods (Groups I and III).

RESULTS

The hepatic fatty infiltration in Group II (TPVS 1 month) (30.12+/-53.92 micron2) is similar to that presented by Group III (Control 1 year) (16.52+/-45.20 micron2), while there is an increase (p<0.001) in Group IV (triple portal vein stenosis 1 year) (182.03+/-371.42 micron2) in relation to the other groups studied. The progressive hepatic fatty infiltration in triple portal vein stenosis rats is associated with a decrease of portal pressure and of the incidence of liver hepatic atrophy, portosystemic collateral circulation and mesenteric venous congestion.

CONCLUSIONS

TPVS produces progressive hepatocytic fatty infiltration in the rat so that this prehepatic portal hypertension experimental model could also be considered as a hepatic steatosis model.

Progressive hepatocytic fatty infiltration in rats with prehepatic portal hypertension

BACKGROUND/AIMS

Homogenous evolution, with a narrow range of portal hypertension, degree of portosystemic shunt and hepatic atrophy has been described in the experimental model of prehepatic portal hypertension in the rat. However the great differences observed in the rats' liver weight could be attributed to a pathological alteration of the liver. Based on this, we performed an evolutive histological study of the liver. This study shows the existence of a progressive hepatocytic fatty infiltration.

METHODOLOGY

Male Wistar rats with portal hypertension induced by triple stenosing ligation of the portal vein at 1 month (group II, n=4) and at 1 year (group IV, n=10) of postoperative evolution were used. The portal pressure, body, liver and splenic weights, types of collateral circulation and degree of mesenteric venous congestion were studied. The intracytoplasmatic lipid microvacuoles were quantified in hepatocytes with an image analyzer (software MIP/CID, Spain). The results were compared with those obtained in control rats with the same evolutive periods (Groups I and III).

RESULTS

The hepatic fatty infiltration in Group II (TPVS 1 month) (30.12+/-53.92 micron2) is similar to that presented by Group III (Control 1 year) (16.52+/-45.20 micron2), while there is an increase (p<0.001) in Group IV (triple portal vein stenosis 1 year) (182.03+/-371.42 micron2) in relation to the other groups studied. The progressive hepatic fatty infiltration in triple portal vein stenosis rats is associated with a decrease of portal pressure and of the incidence of liver hepatic atrophy, portosystemic collateral circulation and mesenteric venous congestion.

CONCLUSIONS

TPVS produces progressive hepatocytic fatty infiltration in the rat so that this prehepatic portal hypertension experimental model could also be considered as a hepatic steatosis model.

Natural killer cell receptors for major histocompatibility complex class I and related molecules in cytomegalovirus infection

Downmodulation of major histocompatibility complex (MHC) class I molecules by cytomegalovirus (CMV) impairs the engagement of specific leucocyte-inhibitory receptors, rendering infected cells vulnerable to natural killer (NK) cells. Members of the murine Ly49 and human KIR families, CD85j (ILT2 or leucocyte Ig-like receptor-1), as well as the CD94/NKG2A-inhibitory killer lectin-like receptor (KLR) fulfil this surveillance role. On the other hand, NK-activating receptors specific to ligands expressed on virus-infected cells may overcome the control by inhibitory receptors. In this regard, NKG2D and Ly49H lectin-like molecules trigger NK-cell functions recognizing, respectively class I-related stress-inducible molecules and the m157 murine CMV glycoprotein. Among a variety of immune evasion strategies, CMV promotes the synthesis of class I surrogates and selectively preserves the expression of some class I molecules in infected cells; moreover, CMV interferes with the expression of ligands for NKG2D. We herein review these aspects of the host-pathogen interaction, discussing a number of open issues.

Immune checkpoints in viral latency

The dynamics of the relationship between the immune system and latent viruses are highly complex. Latent viruses not only avoid elimination by the host's primary immune response, they also remain with the host for life in the presence of strong acquired immunity, often exhibiting periodic reactivation and recurrence from the latent state. The continual battle between reemergent infectious virus and immunological memory cells provides an essential virus-host regulatory loop in latency. In this review, we speculate on the critical importance of immune interference mechanisms by viruses contributing to the regulatory loop in viral homeostasis of latency. Central to the notion of viral homeostasis, we further invoke the concept of threshold limits in naive and memory states of immunity to account for the failure of the host to completely eradicate these intracellular parasites.

Lymphotoxins and cytomegalovirus cooperatively induce interferon-beta, establishing host-virus détente

Tumor necrosis factor (TNF)-related cytokines regulate cell death and survival and provide strong selective pressures for viruses, such as cytomegalovirus (CMV), to evolve counterstrategies in order to persist in immune-competent hosts. Signaling by the lymphotoxin (LT)-beta receptor or TNF receptor-1, but not Fas or TRAIL receptors, inhibits the cytopathicity and replication of human CMV by a nonapoptotic, reversible process that requires nuclear factor kappa B (NF-kappa B)-dependent induction of interferon-beta (IFN-beta). Efficient induction of IFN-beta requires virus infection and LT signaling, demonstrating the need for both host and viral factors in the curtailment of viral replication without cellular elimination. LT alpha-deficient mice and LT beta R-Fc transgenic mice were profoundly susceptible to murine CMV infection. Together, these results reveal an essential and conserved role for LTs in establishing host defense to CMV.

Assessing conservation biology priorities through the development of biodiversity indicators

Biodiversity erosion is now a recognized phenomenon within the scientific community, and it is understood that there is an urgent need for action to relieve this loss. However, no consensus exists on how to go about achieving this goal. This is due to two kinds of problems: namely, that there are many different reasons which can motivate conservation attempts and hence they can lead to different priorities, sometimes in direct contrast with one another; and that of the complexity of the natural world which we have to operate in. Regarding the latter, several authors have lamented a severe lack of theoretical support for many conservation decisions. We briefly review some of the criteria that are commonly adopted in conservation, and indicate some of their problems; we then introduce a new theoretical framework based on the use of a series of biological indicators, many of which have already been proposed in the past but never fully explained and/or adopted. In addition, we propose two indices for one of these potential indicators, i.e. evolutionary potential. We conclude with an appeal for a greater collaboration between conservation scientists and evolutionary biologists, in order to encompass evolutionary evidence in the decision-making process. In doing so, we hope to increase the chances of successful conservation efforts.

Dominance of virus over host factors in cross-species activation of human cytomegalovirus early gene expression

Human cytomegalovirus (HCMV) exhibits a highly restricted host range. In this study, we sought to examine the relative significance of host and viral factors in activating early gene expression of the HCMV UL54 (DNA polymerase) promoter in murine cells. Appropriate activation of the UL54 promoter at early times is essential for viral DNA replication. To study how the HCMV UL54 promoter is activated in murine cells, a transgenesis system based on yeast artificial chromosomes (YACs) was established for HCMV. A 178-kb YAC, containing a subgenomic fragment of HCMV encompassing the majority of the unique long (UL) region, was constructed by homologous recombination in yeast. This HCMV YAC backbone is defective for viral growth and lacks the major immediate-early (IE) gene region, thus permitting the analysis of essential cis-acting sequences when complemented in trans. To quantitatively measure the level of gene expression, we generated HCMV YACs containing a luciferase reporter gene inserted downstream of either the UL54 promoter or, as a control for late gene expression, the UL86 promoter, which directs expression of the major capsid protein. To determine the early gene activation pathway, point mutations were introduced into the inverted repeat 1 (IR1) element of the UL54 promoter of the HCMV YAC. In the transgenesis experiments, HCMV YACs and derivatives generated in yeast were introduced into NIH 3T3 murine cells by polyethylene glycol-mediated fusion. We found that infection of YAC, but not plasmid, transgenic lines with HCMV was sufficient to fully recapitulate the UL54 expression program at early times of infection, indicating the importance of remote regulatory elements in influencing regulation of the UL54 promoter. Moreover, YACs containing a mutant IR1 in the UL54 promoter led to reduced ( approximately 30-fold) reporter gene expression levels, indicating that HCMV major IE gene activation of the UL54 promoter is fully permissive in murine cells. In comparison with HCMV, infection of YAC transgenic NIH 3T3 lines with murine cytomegalovirus (MCMV) resulted in lower (more than one order of magnitude) efficiency in activating UL54 early gene expression. MCMV is therefore not able to fully activate HCMV early gene expression, indicating the significance of virus over host determinants in the cross-species activation of key early gene promoters. Finally, these studies show that YAC transgenesis can be a useful tool in functional analysis of viral proteins and control of gene expression for large viral genomes.

The major immediate-early gene ie3 of mouse cytomegalovirus is essential for viral growth

The significance of the major immediate-early gene ie3 of mouse cytomegalovirus (MCMV) and that of the corresponding ie2 gene of human cytomegalovirus to viral replication are not known. To investigate the function of the MCMV IE3 regulatory protein, we generated two different MCMV recombinants that contained a large deletion in the IE3 open reading frame (ORF). The mutant genomes were constructed by the bacterial artificial chromosome mutagenesis technique, and MCMV ie3 deletion mutants were reconstituted on a mouse fibroblast cell line that expresses the MCMV major immediate-early genes. The ie3 deletion mutants failed to replicate on normal mouse fibroblasts even when a high multiplicity of infection was used. The replication defect was rescued when the IE3 protein was provided in trans by a complementing cell line. A revertant virus in which the IE3 ORF was restored was able to replicate with wild-type kinetics in normal mouse fibroblasts, providing evidence that the defective growth phenotype of the ie3 mutants was due to disruption of the ie3 gene. To characterize the point of restriction in viral replication that is controlled by ie3, we analyzed the pattern of expression of selective early (beta) and late (gamma) genes. While we could detect transcripts for the immediate-early gene ie1 in cells infected with the ie3 mutants, we failed to detect transcripts for representative beta and gamma genes. These data demonstrate that the MCMV transactivator IE3 plays an indispensable role during viral replication in tissue culture, implicating a similar role for the human CMV ie2 gene product. To our knowledge, the ie3 deletion mutants represent the first MCMV recombinants isolated that contain a disruption of an essential gene.

Principles of homeostasis in governing virus activation and latency

The goal of our work is to understand, from the molecular to the organismal level, the principles that drive and sustain lifelong infection by viruses. These infectious agents live in a dynamic equilibrium (homeostasis) with their hosts in which both immune and nonimmune pathways contribute to viral homeostasis. Disruption of these pathways can have dramatic consequences on pathogenesis. Immune responses to infection provide a vital countermeasure by the host but are nonsterilizing. They effect an essential and primary control mechanism for viral growth. Essential nonimmune pathways for effecting control of a viral life cycle relate to the obligate dependency of the virus on its host. For these reasons, we view infections as a highly dynamic interplay that takes place between the pathogen and host. This, in many cases, leads to the establishment of an incurable lifelong infection that remains benign but can become life threatening once key homeostatic pathways are disrupted. We discuss these issues in the context of our studies using cytomegalovirus as a clinically relevant pathogen.

Regulation of transporter associated with antigen processing by phosphorylation

The ATP-binding cassette transporter associated with antigen processing (TAP) is required for transport of antigenic peptides, generated by proteasome complexes in the cytoplasm, into the lumen of the endoplasmic reticulum where assembly with major histocompatibility complex class I molecules takes place. The TAP transporter is a heterodimer of TAP1 and TAP2. Here we show that both TAP1 and TAP2 are phosphorylated under physiological conditions. Phosphorylation induces formation of high molecular weight TAP complexes that contain TAP1, TAP2, tapasin, and class I heterodimers. In addition, a 43-kDa phosphoprotein, which appears to be a kinase, is contained in the phosphorylated TAP-containing complexes. Phosphorylated TAP complexes are able to bind peptides and ATP, however, they are not capable of transporting peptides. After de-phosphorylation, TAP complexes regain the ability to transport peptides. Interestingly, phosphorylation levels of TAP complexes induced by viral infection inversely correlates with a significant reduction in TAP-dependent peptide transport activity. Enhanced TAP phosphorylation appears to be one of several strategies that viruses have exploited to better escape from host immune surveillance. These results demonstrate that major histocompatibility complex class I antigen processing and presentation is modulated by reversible TAP phosphorylation, and implicate the importance of TAP phosphorylation in the regulation of cytotoxic immune response.

Identification of a boundary domain adjacent to the potent human cytomegalovirus enhancer that represses transcription of the divergent UL127 promoter

Transcriptional repression within a complex modular promoter may play a key role in determining the action of enhancer elements. In human cytomegalovirus, the major immediate-early promoter (MIEP) locus contains a highly potent and complex modular enhancer. Evidence is presented suggesting that sequences of the MIEP between nucleotide positions -556 and -673 function to prevent transcription activation by enhancer elements from the UL127 open reading frame divergent promoter. Transient transfection assays of reporter plasmids revealed repressor sequences located between nucleotides -556 and -638. The ability of these sequences to confer repression in the context of an infection was shown using recombinant viruses generated from a bacterial artificial chromosome containing an infectious human cytomegalovirus genome. In addition to repressor sequences between -556 and -638, infection experiments using recombinant virus mutants indicated that sequences between -638 and -673 also contribute to repression of the UL127 promoter. On the basis of in vitro transcription and transient transfection assays, we further show that interposed viral repressor sequences completely inhibit enhancer-mediated activation of not only the homologous but also heterologous promoters. These and other experiments suggest that repression involves an interaction of host-encoded regulatory factors with defined promoter sequences that have the property of proximally interfering with upstream enhancer elements in a chromatin-independent manner. Altogether, our findings establish the presence of a boundary domain that efficiently blocks enhancer-promoter interactions, thus explaining how the enhancer can work to selectively activate the MIEP.

Impaired immunoproteasome assembly and immune responses in PA28-/- mice

In vitro PA28 binds and activates proteasomes. It is shown here that mice with a disrupted PA28b gene lack PA28a and PA28b polypeptides, demonstrating that PA28 functions as a hetero-oligomer in vivo. Processing of antigenic epitopes derived from exogenous or endogenous antigens is altered in PA28-/- mice. Cytotoxic T lymphocyte responses are impaired, and assembly of immunoproteasomes is greatly inhibited in mice lacking PA28. These results show that PA28 is necessary for immunoproteasome assembly and is required for efficient antigen processing, thus demonstrating the importance of PA28-mediated proteasome function in immune responses.

Soluble-polymer supported synthesis of a prostanoid library: identification of antiviral activity

[formula: see text] The prostaglandins are potent natural products taking part in many biological processes. The "convergent generation of diversity" from a "toolbox" of prostanoid components, augmented with additional polymer-supported transformations, can enable construction of valuable libraries. A parallel-pool strategy was used to assemble a small library of prostanoids. The inhibition of a herpes-family virus demonstrated the potential for new drug discovery.

DNA microarrays of the complex human cytomegalovirus genome: profiling kinetic class with drug sensitivity of viral gene expression

We describe, for the first time, the generation of a viral DNA chip for simultaneous expression measurements of nearly all known open reading frames (ORFs) in the largest member of the herpesvirus family, human cytomegalovirus (HCMV). In this study, an HCMV chip was fabricated and used to characterize the temporal class of viral gene expression. The viral chip is composed of microarrays of viral DNA prepared by robotic deposition of oligonucleotides on glass for ORFs in the HCMV genome. Viral gene expression was monitored by hybridization to the oligonucleotide microarrays with fluorescently labelled cDNAs prepared from mock-infected or infected human foreskin fibroblast cells. By using cycloheximide and ganciclovir to block de novo viral protein synthesis and viral DNA replication, respectively, the kinetic classes of array elements were classified. The expression profiles of known ORFs and many previously uncharacterized ORFs provided a temporal map of immediate-early (alpha), early (beta), early-late (gamma1), and late (gamma2) genes in the entire genome of HCMV. Sequence compositional analysis of the 5' noncoding DNA sequences of the temporal classes, performed by using algorithms that automatically search for defined and recurring motifs in unaligned sequences, indicated the presence of potential regulatory motifs for beta, gamma1, and gamma2 genes. In summary, these fabricated microarrays of viral DNA allow rapid and parallel analysis of gene expression at the whole viral genome level. The viral chip approach coupled with global biochemical and genetic strategies should greatly speed the functional analysis of established as well as newly discovered large viral genomes.

Murine cytomegalovirus infection down-regulates MHC class II expression on macrophages by induction of IL-10

Herpesviruses utilize many strategies for weakening the host immune response. For CMV, this includes avoidance of NK clearance and inhibition of MHC class I and class II presentation pathways. In this study, we report that mouse CMV (MCMV) specifically causes a premature and transient activation of host IL-10 very early in the course of infection, resulting in a dramatic and selective reduction in MHC class II surface expression. The expression of IL-10 is normally late in the immune response to a pathogen, serving to dampen the response by suppression of the production of inflammatory cytokines. In infection of macrophages, we show that MCMV induces the production of IL-10, leading to an early and selective reduction in the expression of MHC class II on the surface of the cells. Inhibition of MHC class II expression was not observed in the presence of neutralizing Abs to IL-10 or in macrophages from IL-10-deficient mice. Moreover, MCMV-infected IL-10-deficient mice developed an early and significantly more robust macrophage MHC class II induction than normal mice. Altogether, our results demonstrate that viral induction of an IL-10 autocrine pathway plays an essential early role in selectively reducing MHC class II expression on the surface of APC prior to stimulation by IFN-gamma.

Defective interleukin (IL)-18-mediated natural killer and T helper cell type 1 responses in IL-1 receptor-associated kinase (IRAK)-deficient mice

Interleukin (IL)-18 is functionally similar to IL-12 in mediating T helper cell type 1 (Th1) response and natural killer (NK) cell activity but is related to IL-1 in protein structure and signaling, including recruitment of IL-1 receptor-associated kinase (IRAK) to the receptor and activation of c-Jun NH2-terminal kinase (JNK) and nuclear factor (NF)-kappaB. The role of IRAK in IL-18-induced responses was studied in IRAK-deficient mice. Significant defects in JNK induction and partial impairment in NF-kappaB activation were found in IRAK-deficient Th1 cells, resulting in a dramatic decrease in interferon (IFN)-gamma mRNA expression. In vivo Th1 response to Propionibacterium acnes and lipopolysaccharide in IFN-gamma production and induction of NK cytotoxicity by IL-18 were severely impaired in IRAK-deficient mice. IFN-gamma production by activated NK cells in an acute murine cytomegalovirus infection was significantly reduced despite normal induction of NK cytotoxicity. These results demonstrate that IRAK plays an important role in IL-18-induced signaling and function.

Enhancer requirement for murine cytomegalovirus growth and genetic complementation by the human cytomegalovirus enhancer

The cytomegalovirus (CMV) enhancer is a highly complex regulatory region containing multiple elements that interact with a variety of host-encoded transcription factors. Many of these sequence elements are conserved among the different species strains of CMV, although the arrangement of the various elements and overall sequence composition of the CMV enhancers differ remarkably. To delineate the importance of this region to a productive infection and to explore the possibility of generating a murine CMV (MCMV) under the control of human CMV (HCMV) genetic elements, the MCMV enhancer was resected and replaced either with nonregulatory sequences or with paralogous sequences from HCMV. The effects of these various deletions and substitutions on viral growth in transfected or infected tissue-culture cells were evaluated. We found that mutations in MCMV that eliminate or substitute for the enhancer with nonregulatory sequences showed a severe deficiency in virus synthesis. This growth defect is effectively complemented by the homologous MCMV enhancer as well as the HCMV enhancer. In the latter case, the chimeric viruses (hybrid MCMV strains) containing the molecularly shuffled human enhancer exhibit infectious kinetics similar to that of parental wild-type and wild-type revertant MCMV. These results also show that open reading frames m124, m124.1, and m125 located within the enhancer region are nonessential for growth of MCMV in cells. Most importantly, we conclude that the enhancer of MCMV is required for optimal infection and that its diverged human counterpart can advantageously replace its role in promoting viral infectivity.

Ligand induction of retinoic acid receptors alters an acute infection by murine cytomegalovirus

Here we report that administration of retinoids can alter the outcome of an acute murine cytomegalovirus (MCMV) infection. We show that a crucial viral control element, the major immediate-early enhancer, can be activated by retinoic acid (RA) via multiple RA-responsive elements (DR2) that bind retinoid X receptor-retinoic acid receptor (RAR) heterodimers with apparent dissociation constants ranging from 15 to 33 nM. Viral growth is dramatically increased upon RA treatment of infected tissue culture cells. Using synthetic retinoid receptor-specific agonists and antagonists, we provide evidence that RAR activation in cells is required for mediating the response of MCMV to RA. Oral administration of RA to infected immunocompetent mice selectively exacerbates an infection by MCMV, while cotreatment with an RAR antagonist protects against the adverse effects of RA on MCMV infection. In conclusion, these chemical genetic experiments provide evidence that an RAR-mediated pathway can modulate in vitro and in vivo infections by MCMV.

[Long-term course of blood lipids and body mass index in patients with testicular cancer treated with chemotherapy]

OBJECTIVE

To evaluate whether males with testicular cancer treated with chemotherapy including cisplatin (Qt-C) develop an increase in serum cholesterol and triglyceride levels and in the body mass index (BMI), which might pose a cardiovascular risk.

PATIENTS AND METHODS

Fifty-six male patients with the previous diagnosis of testicular carcinoma, and apparently cured now, were studied. Thirty-six were Qt-C treated. The median age was 28 years and the median follow-up 81 months. The other 20 patients, with testicular cancer stage I and who did not require Qt-C, did not differ in mean age nor in the median of follow-up. Twenty healthy males were also studied, and their cholesterol and triglyceride levels and BMI were compared with those in patients treated with Qt-C at the end of follow-up; both group were of similar age. In all patients (prior to diagnosis and yearly up to the end of the study) and in healthy subjects total serum cholesterol and triglyceride levels were measured, as well as BMI (weight/height2).

RESULTS

Levels of cholesterol, triglycerides and BMI were not different at diagnosis of testicular cancer, both in patients treated with Qt-C and those not receiving such therapy. When comparing yearly cholesterol and triglyceride levels in both groups of patients during the first 6 years of evolution, no significant differences were observed. Again, no differences were observed between patients treated and not treated with Qt-C at the end of the follow-up period regarding cholesterol (211 +/- 41 vs 219 +/- 44 mg/dl; p = 0.51), triglyceride (128 +/- 57 vs 129 +/- 51 mg/dl; p = 0.94) and BMI (25.7 +/- 3.3 vs 25.5 +/- 3.4 kg/m2; p = 0.86) values. No significant differences were observed in the three parameters between parameters in patients treated with Qt-C at the end of follow-up and in healthy males.

CONCLUSIONS

In males with testicular cancer treated with Qt-C, no long term increase in cholesterol, triglyceride, and BMI values was detected, which might predispose to the development of cardiovascular diseases.

Human cytomegalovirus inhibits antigen presentation by a sequential multistep process

The human cytomegalovirus (HCMV) genomic unique short (US) region encodes a family of homologous genes essential for the inhibition of major histocompatibility complex (MHC) class I-mediated antigen presentation during viral infection. Here we show that US3, the only immediate early (IE) gene within the US region, encodes an endoplasmic reticulum-resident glycoprotein that prevents intracellular transport of MHC class I molecules. In contrast to the rapid degradation of newly synthesized MHC class I heavy chains mediated by the early gene product US11, we found that US3 retains stable MHC class I heterodimers in the endoplasmic reticulum that are loaded with peptides while retained in the ER. Consistent with the expression pattern of US3 and US11, MHC class I molecules are retained but not degraded during the IE period of infection. Our data identify the first nonregulatory role of an IE protein of HCMV and suggest that HCMV uses different T-cell escape strategies at different times during the infectious cycle.