Feed gap analysis of dual-purpose chicken production in Tanzania: feed quantity and quality limited production

The demand for chicken meat and eggs exceeds what can be produced in Tanzania, largely due to low productivity of the sector. Feed quantity and quality are the major factors determining the potential production and productivity of chickens. The present study explored the yield gap in chicken production in Tanzania and analyses the potential of increased chicken production as a result of closing the feed gaps. The study focused on feed aspects limiting dual-purpose chicken production in semi-intensive and intensive systems. A total of 101 farmers were interviewed using a semistructured questionnaire and the amount of feed provided to chickens per day was quantified. Feed was sampled for laboratory analysis and physical assessments were made of weights of chicken bodies and eggs. The results were compared with the recommendations for improved dual-purpose crossbred chickens, exotic layers, and broilers. The results show that the feeds were offered in insufficient quantity compared with the recommendations for laying hens (125 g/chicken unit/d). Indigenous chickens were fed 111 and 67 while the improved crossbred chickens were fed 118 and 119 g/chicken unit/d under semi-intensive and intensive systems, respectively. Most feeds fed to dual-purpose chickens were of low nutritional quality, particularly lacking in crude protein and essential amino acids in both rearing systems and breeds. Maize bran, sunflower seedcake, and fishmeal were the main sources of energy and protein in the study area. The study findings show that the important feed ingredients: protein sources, essential amino acids, and premixes were expensive, and were not included in formulating compound feeds by most chicken farmers. Of all 101 respondents interviewed, only one was aware of aflatoxin contamination and its effects on animal and human health. All feed samples contained a detectable concentration of aflatoxins and 16% of them exceeded the allowed toxicity thresholds (>20 µg/kg). We highlight the need for a stronger focus on feeding strategies and ensuring the availability of suitable and safe feed formulations.

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.

Lesser-known bunyavirus infections

This paper reviews less well-known or less widely distributed viruses of the Bunyaviridae family that are nonetheless of significant veterinary and public health concern. These include: Cache Valley fever, Main Drain, Ingwavuma, Bhanja and Heartland viruses. A description of the agents, clinical signs of infection, epidemiology, and insect transmission is provided for each, and the authors discuss current diagnostic strategies plus the lack of control measures.

The NS3 proteins of global strains of bluetongue virus evolve into regional topotypes through negative (purifying) selection

Comparison of the deduced amino acid sequences of the genes (S10) encoding the NS3 protein of 137 strains of bluetongue virus (BTV) from Africa, the Americas, Asia, Australia and the Mediterranean Basin showed limited variation. Common to all NS3 sequences were potential glycosylation sites at amino acid residues 63 and 150 and a cysteine at residue 137, whereas a cysteine at residue 181 was not conserved. The PPXY and PS/TAP late-domain motifs were conserved in all but three of the viruses. Phylogenetic analyses of these same sequences yielded two principal clades that grouped the viruses irrespective of their serotype or year of isolation (1900-2003). All viruses from Asia and Australia were grouped in one clade, whereas those from the other regions were present in both clades. Each clade segregated into distinct subclades that included viruses from single or multiple regions, and the S10 genes of some field viruses were identical to those of live-attenuated BTV vaccines. There was no evidence of positive selection on the S10 gene as assessed by reconstruction of ancestral codon states on the phylogeny, rather the functional constraints of the NS3 protein are expressed through substantial negative (purifying) selection.

Midgut and salivary gland transcriptomes of the arbovirus vector Culicoides sonorensis (Diptera: Ceratopogonidae)

Numerous Culicoides spp. are important vectors of livestock or human disease pathogens. Transcriptome information from midguts and salivary glands of adult female Culicoides sonorensis provides new insight into vector biology. Of 1719 expressed sequence tags (ESTs) from adult serum-fed female midguts harvested within 5 h of feeding, twenty-eight clusters of serine proteases were derived. Four clusters encode putative iron binding proteins (FER1, FERL, PXDL1, PXDL2), and two clusters encode metalloendopeptidases (MDP6C, MDP6D) that probably function in bloodmeal catabolism. In addition, a diverse variety of housekeeping cDNAs were identified. Selected midgut protease transcripts were analysed by quantitative real-time PCR (q-PCR): TRY1_115 and MDP6C mRNAs were induced in adult female midguts upon feeding, whereas TRY1_156 and CHYM1 were abundant in midguts both before and immediately after feeding. Of 708 salivary gland ESTs analysed, clusters representing two new classes of protein families were identified: a new class of D7 proteins and a new class of Kunitz-type protease inhibitors. Additional cDNAs representing putative immunomodulatory proteins were also identified: 5' nucleotidases, antigen 5-related proteins, a hyaluronidase, a platelet-activating factor acetylhydrolase, mucins and several immune response cDNAs. Analysis by q-PCR showed that all D7 and Kunitz domain transcripts tested were highly enriched in female heads compared with other tissues and were generally absent from males. The mRNAs of two additional protease inhibitors, TFPI1 and TFPI2, were detected in salivary glands of paraffin-embedded females by in situ hybridization.

Field-deployable real-time polymerase chain reaction detection of bluetongue and epizootic haemorrhagic disease viral ribonucleic acid

Nucleic acid sequence information from molecular evolution studies of bluetongue virus (BTV) and related epizootic haemorrhagic disease virus (EHDV) strains has resulted in a large database of genomic information. Published sequence data and sequence data from our laboratory were used to design real-time field-deployable reverse transcriptase-polymerase chain reaction assays for the detection of BTV or EHDV viral RNA. The assays used standard RNA extraction and TaqMan chemistries and the entire process was completed in <or=3 h. The reaction conditions have been adapted to run on a field-deployable ruggedised advanced pathogen identification device (RAPID) instrument from Idaho Technologies, Inc. This instrument consists of a 50-lb (22.68 kg) backpack containing everything needed to run the assays. The current assays are specific for United States serotypes of BTV and EHDV; however, new designs based on new sequencing information are being evaluated to improve specificity and sensitivity for additional serotypes. This new technology greatly enhances the speed of virus detection and the ability to monitor disease outbreaks.

Molecular investigations of orbivirus/vector interactions

Defining predictors for insect-transmitted virus (arbovirus) disease cycles requires an understanding of the molecular interactions between the virus and vector insect. Studies of orbiviruses from numerous geographic regions have indicated that virus genes are affected by insect population differences. Therefore, the authors have initiated genetic studies of Culicoides sonorensis, isolating cDNAs for characterisation of differential insect gene expression, as well as a gene discovery project. Previous work identified insect transcripts elevated in orbivirus-infected female midguts at one day post infection (pI). Here, we report cDNAs that were more abundant in midguts two days following an epizootic haemorrhagic disease virus feeding, as well in head/salivary glands at three days pI. Of the cDNAs identified in midguts at two days pI, three encode translational machinery components, and three encode components that affect cellular structural features. Of the differentially expressed salivary gland cDNAs, only one was homologous to a previously identified gene, a putative odorant binding protein.

Antigen capture competitive enzyme-linked immunosorbent assays using baculovirus-expressed antigens for diagnosis of bluetongue virus and epizootic hemorrhagic disease virus

Bluetongue virus (BTV) and epizootic hemorrhagic disease virus (EHDV) are orbiviruses that infect both livestock and wild ruminants. Antigenic cross-reactivity between BTV and EHDV often results in serologic misdiagnosis. Competitive enzyme-linked immunosorbent assays (c-ELISAs) show increased sensitivity and specificity for the identification of these viral diseases; however, the preparation of cell culture-derived viral antigen for these tests is laborious and variable from batch to batch, and the resulting antigen may be infectious. To overcome these problems, the genes coding for a structural protein, VP7, of BTV and EHDV were cloned into baculovirus and the recombinant proteins were expressed in Sf9 cultured insect cells. Recombinant viral proteins released into the baculovirus-infected Sf9 cell culture supernatant were used in antigen capture c-ELISAs (Ag Cap c-ELISA) tests that specifically detected antibody in the serum of cattle experimentally infected with BTV and EHDV. The diagnostic utility of the Ag Cap c-ELISA was demonstrated by comparison with a commercial c-ELISA. The Ag Cap c-ELISA offers the advantages of using an easily produced, easily standardized, noninfectious antigen that does not require further purification or concentration.

Differentially expressed midgut transcripts in Culicoides sonorensis (Diptera: ceratopogonidae) following Orbivirus (reoviridae) oral feeding

Understanding the vector insect's gene expression response to a virus infection may aid design of control measures for arbovirus diseases. Culicoides sonorensis is a vector of several agriculturally important pathogens, such as epizootic haemorrhagic disease virus (EHDV) that causes disease in ruminants. Two approaches, differential display and suppression subtractive hybridization, were used to identify 400+ Culicoides transcripts that were more abundant in midguts 1 day following an oral meal containing EHDV. Of these, quantitative PCR confirmed seven to be more abundant in virus-fed midguts than controls. One such transcript encodes a putative RNA editase, CsRED1, induced by dsRNA. Transcripts encoding putative receptors involved in cell differentiation included CsLAR, a protein tyrosine phosphatase, and CsFZ2, homologous to the wingless receptor in D. melanogaster. Transcripts encoding putative translation machinery components included CseIF3, CseIF5A and CsRPS6. Overall, the cDNA fragments identified in this study increased in the midgut at one day postfeeding; by 2 days postfeeding, increases in transcript levels shifted from the midgut to the remainder of the infected midge.

Verification of bluetongue virus S9 segment nucleotide sequences

During the course of our bluetongue virus (BTV) nucleic acid sequence investigations, conflicts among United States (US) prototype BTV S9 genome segment sequences deposited in GenBank were noted. In order to rectify these inter-laboratory discrepancies, the S9 segments of Arthropod-borne Animal Diseases Research Laboratory (ABADRL)-stored US prototype BTV 2, BTV 10, BTV 11, BTV 13, and BTV 17 isolates were resequenced. Our S9 sequences, determined by direct sequencing of full-length reverse transcriptase-polymerase chain reaction (RT-PCR) generated amplicons, shared 99% or greater nucleotide identity with one or more respective S9 sequences previously reported. Possible sources of remaining unsupported US prototype BTV S9 sequences were evaluated by amplifying and sequencing the S9 segments of BTV 2 Ona A strain, South African (SA) prototype BTV 1, BTV 2, and BTV 4 strains, and the North American (NA) prototype epizootic hemorrhagic disease virus (EHDV) serotype 2 (Alberta) strain. Comparative analysis using these S9 sequences, as well as sequences of US BTV 2 field isolates, identified potential contributors to inter-laboratory sequence disagreements.

Oliguria. A sign of renal success or impending renal failure?

Limiting renal impairment begins with identifying patients at increased risk for renal dysfunction (monitoring of renal function is important in these patients) and understanding the physiology of urine formation, the influence of anesthetic drugs, and intraoperative events on the physiology and pathophysiology of renal function. The fundamental principles emphasized in this article include avoidance of hypovolemia or renal hypoperfusion (e.g., hypotension, decreased cardiac output) in patients at risk (because of pre-existing disease or the nature of the operative procedure) and limitation of toxins that might jeopardize residual renal function. Direct monitors of renal well-being are still in the rudimentary stage of development. Indirect measures of renal function (CVP, MAP) are used on a minute-to-minute basis. The clinical measurement of urine output still is relied on when evaluating renal function over longer time intervals. Currently, only one drug (N-acetylcysteine) improves renal outcome after a high-risk procedure (radiocontrast administration) prophylactically. Manipulation of autorenal regulatory vasodilators (e.g., nitric oxide, PGE2) and vasoconstrictors (e.g., endothelin, vasopressin, angiotensin II) may prove helpful in the future. Currently, maintenance of adequate intravascular volume, MAP, and cardiac output are the most important renal protective measures an anesthesiologist can provide to preserve renal function high-risk patients.

Perioperative hypoxia. The clinical spectrum and current oxygen monitoring methodology

When searching for the source of hypoxia, the anesthesiologist and intensivist one served best by treating the patient in an organized approach--beginning with the environmental and pulmonary sources, searching for anemic and circulatory sources, and finally ruling out the less common histocytic causes. When treating hypoxia, the first maneuver should be to administer oxygen, ensure airway, ventilation, and circulation (the ABCs of basic life support). Further monitoring is addressed at global assessments and specific organ systems (especially in high-risk patients or during high-risk procedures). The ability to directly measure the oxygenation, blood flow, and function in each individual organ of the body is not yet available. Efforts are advancing in the ability to measure the function of important tissue beds, such as the brain and splanchnic circulation. In this regard, Table 5 provides a summary of the spectrum of monitoring technology available for various organs.

Relationship between exposure to community violence and psychological distress: linear or curvilinear?

This paper presents data testing the hypothesis that the relationship between exposure to recurring community violence during high school years and later experiencing of psychological distress symptoms is a quadratic curvilinear one. Data were collected between 1994-1996 by self-administered questionnaires using multi-item scales; the sample (N = 452) comprises older urban adolescents. Although exposure to community violence was positively and linearly related to psychological distress, no statistically significant quadratic curvilinear relationship was found between community violence and psychological distress.

Validation of a reverse transcriptase multiplex PCR test for the serotype determination of U.S. isolates of bluetongue virus

Bluetongue (BT) is an arthropod-borne viral disease affecting ruminants primarily in tropical and temperate regions of the world. Of the 24 serotypes of BT virus (BTV) identified worldwide, five have been found in the United States. Serotype identification of BTV isolates is important to the epidemiology of the virus, but current methods are cumbersome. A single-tube multiplex reverse transcriptase polymerase chain reaction (mRT-PCR) assay, previously developed for the serotype determination of U.S. BTV isolates, was evaluated. The determination of serotype was based on the size of the resultant amplified product. The procedure was evaluated using all 24 serotypes of BTV and nine serotypes of epizootic hemorrhagic disease virus (EHDV), a closely related orbivirus. Only the five U.S. serotypes of BTV were detected by the mRT-PCR. The assay was further tested using 132 BTV isolates originating from 24 western and southern states of the United States, from several different host species, spanning a period of 24 years. The serotypes of the isolates were determined by both a virus neutralization (VN) procedure and the mRT-PCR. Comparison of the mRT-PCR to the standard VN showed that the mRT-PCR successfully identified the serotypes of 130 of the isolates and was shown to be more reliable and specific than the VN assay.

Phylogenetic analysis of the S7 gene does not segregate Chinese strains of bluetongue virus into a single topotype

Bluetongue virus (BTV) infection of ruminants is endemic throughout tropical and subtropical regions of the world. The S7 gene segments of prototype Chinese strains of BTV serotypes 1, 2, 3, 4, 12, 15, and 16 were sequenced and compared to the same genes of prototype strains of BTV from the US, Australia, and South Africa. The S7 genes and predicted VP7 proteins of the Chinese viruses were relatively conserved, with the notable exception of serotype 15. Furthermore, phylogenetic analysis of the S7 genes did not predict geographic origin of the various strains of BTV.

Phylogenetic relationships of bluetongue viruses based on gene S7

Previous phylogenetic analyses based on bluetongue virus (BTV) gene segment L3, which encodes the inner core protein, VP3, indicated a geographical distribution of different genotypes. The inner core protein, VP7, of BTV has been identified as a viral attachment protein for insect cell infection. Because the inner core proteins are involved with infectivity of insect cells, we hypothesized that certain VP7 protein sequences are preferred by the insect vector species present in specific geographic locations. We compared the gene segment S7, which encodes VP7, from 39 strains of BTV isolated from Central America, the Caribbean Basin, the United States, South Africa and Australia. For comparison, the S7 sequences from strains of the related orbiviruses, epizootic hemorrhagic disease virus (EHDV) and African horse sickness virus (AHSV) were included. The S7 gene was highly conserved among BTV strains and fairly conserved among the other orbiviruses examined. VP7 sequence alignment suggests that the BTV receptor-binding site in the insect is also conserved. Phylogenetic analyses revealed that the BTV S7 nucleotide sequences do not unequivocally display geographic distribution. The BTV strains can be separated into five clades based on the deduced VP7 amino acid sequence alignment and phylogeny but evidence for preferential selection by available gnat species for a particular VP7 clade is inconclusive. Differences between clades indicate allowable variation of the VP7 binding protein.

PCR detection of North American and Central African isolates of epizootic hemorrhagic disease virus (EHDV) based on genome segment 10 of EHDV serotype 1

PCR amplification technology for the detection of epizootic hemorrhagic disease virus (EHDV) ribonucleic acid in cell culture and clinical specimens was developed. With oligoribonucleotide primers selected from genome segment 10 of EHDV serotype 1 (EHDV-1), which codes for two nonstructural proteins (NS3 and NS3a), the PCR-based assay resulted in a 535-bp PCR product. RNAs from North American EHDV-1 prototype, EHDV-2 prototype, and a number of EHDV field isolates, including the Central African isolates of EHDV-5 and EHDV-318 propagated in cell cultures, were detected by this PCR-based assay. The specific 535-bp PCR products were visualized onto agarose gels, and the identity of the PCR products was confirmed by chemiluminescent hybridization with a 352-bp internal probe. The sensitivity of the EHDV PCR assay was increased by chemiluminescent hybridization; by this EHDV-NS3 PCR, 10 fg of EHDV RNA was detected (equivalent to 600 viral particles). Amplification product was not detected when the PCR-based assay was applied to RNAs from North American bluetongue virus prototype serotypes 2, 10, 11, 13, and 17; total nucleic acid extracts from uninfected BHK-21 cells; or unfractionated blood from calves and deer that were EHDV seronegative and virus isolation negative. The described EHDV PCR-based assay with primers derived from segment 10 of EHDV-1 resulted in detection of EHDV RNA from blood and tissues collected from calves and deer with natural and experimental EHDV infections and provides a valuable tool to study the epidemiology of EHDV infection in susceptible ruminants.

The effects of pharmacological and lentivirus-induced immune suppression on orbivirus pathogenesis: assessment of virus burden in blood monocytes and tissues by reverse transcription-in situ PCR

We investigated the effects of pharmacological and lentivirus-induced immunosuppression on bluetongue virus (BTV) pathogenesis as a mechanism for virus persistence and induction of clinical disease. Immunologically normal and immunosuppressed sheep were infected subcutaneously with BTV serotype 3 (BTV-3), a foreign isolate with unknown pathogenicity in North American livestock, and with North American serotype 11 (BTV-11). Erythrocyte-associated BTV RNA was detected earlier and at greater concentrations in sheep treated with immunosuppressive drugs. Similarly, viral RNA and infectious virus were detected in blood monocytes earlier and at higher frequency in immunosuppressed animals: as many as 1 in 970 monocytes revealed BTV RNA at peak viremia, compared to <1 in 10(5) monocytes from immunocompetent sheep. Animals infected with BTV-3 had a higher virus burden in monocytes and lesions of greater severity than those infected with BTV-11. BTV RNA was detected by in situ hybridization in vascular endothelial cells and cells of monocyte lineage, but only in tissues from immunocompromised animals, and was most abundant in animals infected with BTV-3. In contrast, reverse transcription-in situ PCR showed BTV RNA from both viral serotypes in high numbers of tissue leukocytes and vascular endothelial cells from both immunosuppressed and, to a lesser extent, immunocompetent animals. Collectively, these findings show that BTV infection is widely distributed during acute infection but replication is highly restricted in animals with normal immunity. These findings also suggest that in addition to virulence factors that define viral serotypes, immunosuppression could play a role in the natural history of orbivirus infection, allowing for higher virus burden, increased virus persistence, and greater potential for acquisition of virus by the arthropod vector.

Sequence and cognitive analyses of two virulence-associated markers of bluetongue virus serotype 17

Genome segments 2 and 3 were completely sequenced for one virulent and one avirulent bluetongue serotype 17 (BLU-17). These two segments were previously shown to exhibit virulence-associated markers. The marker on segment 2 was characterized as a change in the neutralization domain on its protein product, VP2. The nucleotide sequences for segments 2 were 94.5% identical, and their predicted proteins differed by 34 amino acids or 3.7%. Three clusters of variability were identified which may be involved with viral neutralization. These variable regions were compared to mutations for published monoclonal antibody-resistant variants of BLU. The marker on segment 3 was characterized as a mobility shift in polyacrylamide gel electrophoresis (PAGE). The nucleotide sequences were 95.0% identical, and their predicted proteins differed by four amino acids or 0.4%. These amino acid changes were relatively conserved; therefore, they are not likely responsible for virulence. The segment 3 sequences were compared to published sequences, and evidence was found to suggest that the virulent isolate had naturally reassorted between a BLU-17 and BLU-10 isolate.

Epizootic hemorrhagic disease: analysis of tissues by amplification and in situ hybridization reveals widespread orbivirus infection at low copy numbers

A recent outbreak of hemorrhagic fever in wild ruminants in the northwest United States was characterized by rapid onset of fever, followed shortly thereafter by hemorrhage and death. As a result, a confirmed 1,000 white-tailed deer and pronghorn antelope died over the course of 3 months. Lesions were multisystemic and included severe edema, congestion, acute vascular necrosis, and hemorrhage. Animals that died with clinical signs and/or lesions consistent with hemorrhagic fever had antibody to epizootic hemorrhagic disease virus serotype 2 (EHDV-2) by radioimmune precipitation but the antibody was limited exclusively to class immunoglobulin M. These findings, indicative of acute infection, were corroborated by the observation that numerous deer were found dead; however, clinically affected deer were rarely seen during the outbreak. Furthermore, only in animals with hemorrhagic lesions was EHDV-2 isolated and/or erythrocyte-associated EHDV-2 RNA detected by serotype-specific reverse transcription (RT)-PCR. By using a novel RT in situ PCR assay, viral nucleic acid was localized to the cytoplasm of large numbers of tissue leukocytes and vascular endothelium in tissues with hemorrhage and to vessels, demonstrating acute intimal and medial necrosis. Because PCR amplification prior to in situ hybridization was essential for detecting EHDV, the virus copy number within individual cells was low, <20 virus copies. These findings suggest that massive covert infection characterized by rapid dissemination of virus facilitates the severe and lethal nature of this disease.

Inhaled nitric oxide (40 ppm) during one-lung ventilation, in the lateral decubitus position, does not decrease pulmonary vascular resistance or improve oxygenation in normal patients

OBJECTIVES

To determine the effects of inhaled nitric oxide (NO) on venous admixture (Qs/Qt), mean pulmonary artery pressure (MPAP), and pulmonary vascular resistance (PVR) in patients undergoing one-lung ventilation (1LV) in the lateral decubitus position.

DESIGN

Prospective, blinded, crossover.

SETTING

University hospital.

PARTICIPANTS

Six adult patients scheduled for thoracotomy.

INTERVENTIONS

Patients were anesthetized with thoracic epidural lidocaine, intravenous fentanyl, and inhaled isoflurane and were monitored with a systemic and pulmonary artery catheter (PAC). In the lateral decubitus position, the dependent lung was ventilated with 70% oxygen (O2) and 30% nitrogen (N2) for the control 1LV condition. For the experimental 1LV condition, the dependent lung was ventilated with the same gas concentration + NO at 40 ppm. Patients were alternated between the control and the experimental NO (40 ppm) conditions every 15 minutes for as long as the case would allow.

MEASUREMENTS AND MAIN RESULTS

During all conditions, oxygenation, Qs/Qt, and pulmonary and systemic hemodynamics were measured in a double-blinded fashion. The mean PVR during 1LV was 128 +/- 39 (SD) dyne.s.cm(-5). Inhaled NO at 40 ppm did not affect MPAP, PVR, or Qs/Qt.

CONCLUSIONS

Inhaled NO at 40 ppm, during 1LV in the lateral decubitus position, did not significantly decrease MPAP in patients with normal baseline PVR. Oxygenation and Qs/Qt did not change in this setting because MPAP was not altered. At present, interventions other than administration of inhaled NO should be applied to patients with normal PVR who experience hypoxia during one-lung ventilation.

Bluetongue virus detection: a safer reverse-transcriptase polymerase chain reaction for prediction of viremia in sheep

A reversible target capture viral RNA extraction procedure was combined with a reverse-transcriptase nested polymerase chain reaction (PCR) to develop a capture PCR assay providing a rapid and safe prediction method for circulating bluetongue virus in infected ruminants. This new assay was compared with virus isolation and a recently developed antigen-capture enzyme-linked immunosorbent assay (ELISA) for the detection of bluetongue virus. Eight Warhill crossbred sheep were inoculated subcutaneously with bluetongue virus serotype 10, and blood samples were taken sequentially over a period of 28 days. The capture PCR detected the peak of viremia, as determined by virus isolation and antigen-capture ELISA, from day 5 to day 14 after challenge. The results indicate that the rapid-capture bluetongue virus PCR provides a rapid indicator of samples in which virus can be isolated. In addition, this capture bluetongue virus PCR procedure does not require a lengthy phenol extraction or the use of the highly toxic methyl mercury hydroxide denaturant.

Molecular characterization of the segment 2 gene of epizootic hemorrhagic disease virus serotype 2: gene sequence and genetic diversity

The complete nucleotide sequence of the gene encoding the major outer capsid protein VP2 from the Alberta isolate of epizootic hemorrhagic disease virus serotype 2 (EHDV-2) was determined. Complementary DNA (cDNA) corresponding to segment 2 was 3002 nucleotides in length with a single open reading frame that encoded a VP2 of 982 amino acids. Although the VP2 from EHDV-2 was only 34% homologous to the cognate protein from EHDV-1, their predicted hydropathic profiles were similar, suggesting that conservation of structure is important biologically to these capsid proteins. Sequence analysis of six North American EHDV-2 field isolates showed a high degree of comparative genetic identity (> 97%). Phylogenetic profiles constructed suggest that regionalization of the viruses within the North American continent has contributed to the genetic diversity.

Development of polymerase chain reaction for specific identification of epizootic hemorrhagic disease virus serotype 1

The diagnostic potential of the polymerase chain reaction (PCR) for specific identification of epizootic hemorrhagic disease virus serotype 1 (EHDV-1) in cell culture and clinical specimens was evaluated. Using oligonucleotide primers, selected from genome segment 2 of EHDV-1 (New Jersey strain), the PCR-based assay resulted in a 862 base pair (bp) PCR product. EHDV-1 RNA from United States prototype serotype 1 and a number of EHDV-1 field isolates, propagated in cell cultures, were detected by this PCR based assay. The specific 862 bp PCR products were visualized on ethidium bromide-stained agarose gel. Identity of the PCR product was confirmed by chemiluminescent hybridization with non radiolabelled internal probe. Using chemiluminescent hybridization, the sensitivity of the PCR assay was 1.0 fg of virus RNA (equivalent to 60 virus particles). Amplification product was not detected when the PCR-based assay was applied to RNA from EHDV serotype 2 (EHDV-2); the United States bluetongue virus (BLU) prototypes serotypes 2, 10, 11, 13, and 17; total nucleic acid extracts from uninfected BHK-21 cell; or blood cells from calves and deer that were EHDV-seronegative and virus isolation negative. Application of this EHDV-1 PCR-based assay to clinical samples resulted in detection of EHDV-1 RNA from blood samples, collected from a calf experimentally infected with EHDV-1. The described PCR-based assay provides a simple, rapid, sensitive, specific and inexpensive method for specific identification of EHDV-1 infection in susceptible ruminants.

Geographical genetic variation in the gene encoding VP3 from the Alberta isolate of epizootic hemorrhagic disease virus

The complete nucleic acid and deduced amino acid sequences of gene segment 3 and the encoded VP3 from the North American, Alberta isolate of epizootic hemorrhagic disease virus serotype 2 (EHDV-2) are reported. Complementary DNA corresponding to segment 3 was 2768 nucleotides in length with an open reading frame of 2697 base pairs which encoded a VP3 polypeptide of 899 amino acid residues. Sequence comparison with genome segment 3 and VP3 from the Australian strain of EHDV-2 indicated genotypic and phenotypic homologies of 79% and 94%, respectively. Two North American field isolates of EHDV-2, as well as EHDV-1 (New Jersey isolate), had virtually identical homology to the Alberta isolate. Sequence analysis delineated North American EHDV strains as members of a genetically homologous and geographically distinct group of orbiviruses (topotype). The data support the hypothesis that geographic isolation between North American and Australian orbiviruses has permitted the viral topotypes to maintain their genetic distinctness.

A model for the membrane topology of the NS3 protein as predicted from the sequence of segment 10 of epizootic haemorrhagic disease virus serotype 1

Segment 10, encoding nonstructural proteins 3 (NS3) and 3a (NS3a) of epizootic haemorrhagic disease virus serotype 1 (EHDV-1) was sequenced. Computer motif recognition programs were used for interpretation of the sequence data to predict a structure for NS3. Integral membrane protein theories were then applied to produce a general topological model for the EHDV-1 NS3 protein. Homology was observed between EHDV-1 NS3 integral membrane motifs and those similarly observed in the cognate proteins of other orbiviruses.

Complete nucleotide sequence of RNA segment 3 of bluetongue virus serotype 2 (Ona-A). Phylogenetic analyses reveal the probable origin and relationship with other orbiviruses

The nucleotide sequence of the RNA segment 3 of bluetongue virus (BTV) serotype 2 (Ona-A) from North America was determined to be 2772 nucleotides containing a single large open reading frame of 2703 nucleotides (901 amino acid). The predicted VP3 protein exhibited general physiochemical properties (including hydropathy profiles) which were very similar to those previously deduced for other BTV VP3 proteins. Partial genome segment 3 sequences, obtained by polymerase chain reaction (PCR) sequencing, of BTV isolates from the Caribbean were compared to those from North America, South Africa, India, Indonesia, Malaysia and Australia, as well as other orbiviruses, to determine the phylogenetic relationships amongst them. Three major BTV topotypes (Gould, A.R. (1987) Virus Res. 7, 169-183) were observed which had nucleotide sequences that differed by approximately 20%. At the molecular level, geographic separation had resulted in significant divergence in the BTV genome segment 3 sequences, consistent with the evolution of distinct viral populations. The close phylogenetic relationship between the BTV serotype 2 (Ona-A strain) from Florida and the BTV serotypes 1, 6 and 12 from Jamaica and Honduras, indicated that the presence of BTV serotype 2 in North America was probably due to an exotic incursion from the Caribbean region as previously proposed by Sellers and Maaroof ((1989) Can. J. Vet. Res. 53, 100-102) based on trajectory analysis. Conversely, nucleotide sequence analysis of Caribbean BTV serotype 17 isolates suggested they arose from incursions which originated in the USA, possibly from a BTV population distinct from those circulating in Wyoming.

Sequence analysis of the non-structural protein 2 from epizootic hemorrhagic disease viruses

The non-structural protein 2 (NS2) of epizootic hemorrhagic disease virus serotype 1 (EHD-1) was cloned and sequenced. The NS2 gene was found to be 1185 bp containing a single open reading frame that encodes a 376 amino acid protein. A 97% nucleic acid identity was found between EHD-1 and a previously published NS2 sequence of EHD-2. Only a 60% nucleic acid identity was found between EHD and the bluetongue virus (BTV) serogroup. Comparison of the deduced amino acid sequences revealed 97% identity within the EHD serogroup, and less than or equal to 43% identity between serogroups.

The smallest gene of the orbivirus, epizootic hemorrhagic disease, is expressed in virus-infected cells as two proteins and the expression differs from that of the cognate gene of bluetongue virus

The smallest gene (S10) of the virus of epizootic hemorrhagic disease of deer (EHD, serotype 2) is expressed as two proteins in virus-infected cells. By contrast, the non-structural proteins (NS3 and NS3A) encoded in the smallest gene of bluetongue (BT) viruses are difficult to detect in virus-infected cells. The nucleotide sequence of S10 of EHDV-2 contains two in-frame initiation codons which allow for translation of proteins of mol. wt. 25503 and 23921 analogous to NS3 and NS3A of BT viruses. The S10 genes of BT viruses are highly conserved (82%-99%); the nucleotide sequence similarity of S10 of EHDV-2 and BT viruses is about 64%. Some structural features of NS3 and NS3A are conserved in the two viruses, despite the divergence in the amino acid sequences of the proteins. The hydrophobic domains of the proteins and the putative transmembrane sequences are conserved, as are potential glycosylation sites in the proteins. A cluster of proline residues, which is conserved at residues 36-50 in all of the published sequences of NS3 of BT viruses, is conserved exactly in the alignment of the sequence of NS3 of EHDV-2 with that of the BT viruses. An explanation for the differences in expression of NS3/NS3A in EHD and BT viruses was not evident in comparing the nucleotide sequences of S10 of the viruses.

Development of a nested-PCR test based on sequence analysis of epizootic hemorrhagic disease viruses non-structural protein 1 (NS1)

Two orbiviruses, epizootic hemorrhagic disease (EHD) and bluetongue (BTV) viruses, cause disease in domestic and wild ruminant species. The gene that encodes non-structural protein 1 (NS1) of EHD virus, serotype 1, was sequenced and compared to EHD and BTV NS1 sequences. The NS1 gene was found to be more conserved than the VP3 gene, and was selected as a target for polymerase chain reaction (PCR) amplification. The NS1 genes of several BTV viruses and another orbivirus, African horse sickness (AHS), were compared to the EHD NS1 genes. This information was used to develop a capture nested-PCR for detection and differentiation of EHD from BTV viral RNA.

Nested and multiplex polymerase chain reactions for the identification of bluetongue virus infection in the biting midge, Culicoides variipennis

Two polymerase chain reaction tests for the detection of bluetongue viral (BLU) RNA in the principal North American insect vector, Culicoides variipennis, were developed. The BLU serogroup specific test used the highly expressed non-structural protein 1 gene as the target gene and two amplification steps. First a 1228 base pair product was amplified using an outer primer pair, then a second amplification using a nested or internal primer pair produced a 930 base pair product. This nested PCR test was found to be very sensitive detecting an equivalent to 1 plaque-forming unit of BLU viral RNA extracted from infected biting midges. The serotype specific test used a multiplex PCR approach in which five different primer pairs were used simultaneously. Each pair was based on the variable outer capsid protein VP2 gene of the five US serotypes generating specific product which were easily identified by size difference. The sensitivity of the multiplex PCR was less sensitive than the nested-PCR but sufficient for use with field collected samples. These tests provide valuable tools for epidemiologic studies of BLU disease.

Reperfusion injury and exhaled hydrogen peroxide

Reactive oxygen species have been implicated in the pathophysiology of lung injury associated with the sequence of ischemia-reperfusion. To study this, we measured the exhaled breath hydrogen peroxide concentration [H2O2] in human and canine models of reperfusion lung injury. Our models were patients subjected to cardiopulmonary bypass (CPB) (Group 1), patients undergoing pulmonary thromboendarterectomy (Group 2), canine single lung transplant (Group 3), and patients subjected to peripheral ischemia resulting from aortic cross-clamping or tourniquet application (Group 4). In addition, we studied two groups with severe lung injury as positive controls. These consisted of hydrochloric acid (HCl)-induced canine lung injury (Group 5) and patients with adult respiratory distress syndrome (Group 6). The exhaled H2O2 was collected by using a -2 degrees C glass coil and assayed by a spectrophotometric method. In Group 1 samples were collected before and immediately after CPB. Group 2 samples were obtained before CPB, immediately after CPB, 3 h later, and daily until extubation. Samples in Group 3 were collected before lung transplant, and hourly for 3 h beginning immediately afterward. Group 4 samples were collected at the onset of reperfusion. Samples from Group 5 were collected before HCl and after HCl injury, at 0.5-1.5 and 2-3 h. Group 6 samples were collected when criteria for adult respiratory distress syndrome were met. Groups 1, 3, and 4 exhibited no significant increases in exhaled [H2O2] compared to control values. Group 2 had significantly increased [H2O2] (5.59 +/- 3.07 x 10(-7) mol/L, P = 0.028) on postoperative Day 2, but there was no correlation of [H2O2] with physiologic indicators of lung injury.(ABSTRACT TRUNCATED AT 250 WORDS)

Prevalence of bluetongue virus expression in leukocytes from experimentally infected ruminants

Replication of bluetongue virus (BTV) in leukocytes from the blood of sheep, cattle, elk, and mule deer inoculated with BTV serotype 10 or 17 was assessed by immunocytochemical staining and dot blot northern hybridization to determine if differences in the prevalence of infection in this blood fraction might account for the differences in clinical disease among these species. Viremia was confirmed by virus isolation in all inoculated animals. Analysis of leukocytes with monoclonal antibodies specific for BTV proteins revealed low numbers of infected leukocytes in only 2 sheep 8 days after inoculation with BTV serotype 10. Most of the cells expressing BTV were identified morphologically as monocytes; approximately 10% of infected cells were lymphocytes. Bluetongue virus was not detected by use of dot-blot hybridization on samples of blood. Our results suggest that differential infection of leukocytes does not account for the pronounced differences in clinical signs and pathologic changes among ruminants.

Bluetongue virus in sheep and cattle and Culicoides variipennis and C. stellifer (Diptera: Ceratopogonidae) in Louisiana

The transmission of bluetongue virus (BLU) to sheep and cattle relative to Culicoides abundance and infection was studied in two areas of the Louisiana State University Agricultural Center, Baton Rouge, LA. The seroprevalence of BLU in beef cattle was 70.5% in 1989 and 37.0% in 1990; 2 of 37 animals tested in both years became positive, indicating active transmission. The prevalence of BLU in sheep decreased from 52.2% in 1989 to 34% in 1990; seroconversion was not detected. Serotypes of positive sheep were as follows: 13 sheep were positive for BLU-13, 6 for BLU-17, 2 for BLU-2, and 2 for both BLU-13 and BLU-17. The seroprevalence of BLU virus in dairy bulls increased from 15.4% in 1989 to 47.4% in 1990; 0 and 7 seroconversions occurred in 1989 and 1990, respectively. Serotypes of BLU from the bulls were as follows: five bulls for BLU-13; two for BLU-17; one for BLU-13 and BLU-17; and one for BLU-13, BLU-17, and BLU-2. Peaks in the abundance of Culicoides variipennis (Coquillett) and C. stellifer (Coquillett) collected in New Jersey light traps corresponded with the suspected transmission dates during 1990. Bluetongue viral RNA was detected in one of 381 pools (6,072 flies) of C. variipennis; no virus was detected in 125 pools (884 flies) of C. stellifer.

General anesthesia and exhaled breath hydrogen peroxide

To study the role of free radical formation on the impairment of pulmonary function seen with general anesthesia, we measured the hydrogen peroxide (H2O2) concentration in the exhaled breath condensate of 27 patients. Patients were divided into three study groups: a healthy patient group (group 1, n = 15) consisting of ASA physical status 1 and 2 patients undergoing elective noncardiothoracic surgery; a specific anesthetic event group (group 2, n = 6) composed of patients undergoing cardiopulmonary bypass (CPB); and a positive control group (group 3, n = 6) consisting of patients with the adult respiratory distress syndrome (ARDS). The exhaled breath condensate was collected by diverting exhaled breath through a glass condensation coil submerged in an ice/salt water bath. The exhaled breath condensate samples were then assayed using a spectrophotometric method. In group 1, samples were collected before and after the induction of general anesthesia with intravenous drugs, and before and after the administration of the inhalational anesthetics isoflurane (1.5%) (n = 7) or N2O (70%) (n = 8). In group 2, samples were collected pre- and post-CPB, and in group 3, when specific diagnostic criteria for ARDS were met. There was no significantly detectable H2O2 (not significantly different from zero) in any of the samples from the group 1 patients. Similarly, group 2 patients had exhaled breath H2O2 concentrations near zero except for one patient who was positive for the lupus anticoagulant. Group 3 patients had a mean (+/- SE) exhaled breath H2O2 concentration of 0.55 (+/- 0.08) microM, which was significantly greater than zero (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Ordering and administration of sedatives and analgesics during the withholding and withdrawal of life support from critically ill patients

OBJECTIVE

To determine why and how sedatives and analgesics are ordered and administered during the withholding and withdrawal of life support from critically ill patients.

DESIGN

Prospective case series.

SETTING

Medical-surgical intensive care units at a county hospital and a university hospital.

PATIENTS

Consecutive 1-year sample of 22 patients from whom life support was withheld or withdrawn in one intensive care unit at a county hospital and a random sample of 22 similar patients in the intensive care unit in the university hospital over the same period.

MAIN OUTCOME MEASURES

Physicians and nurses were interviewed to determine their reasons for ordering and administering drugs, and medical records were reviewed to document amounts of drugs ordered and administered.

RESULTS

Drugs were given to 75% of patients during withholding and withdrawal of life support. Patients who did not receive medication were comatose and considered incapable of benefiting from sedation and analgesia. The median time until death following the initiation of the withholding or withdrawal of life support was 3.5 hours in the patients who received drugs and 1.3 hours in those patients who did not (P, not significant). Physicians ordered drugs to decrease pain in 88% of patients, to decrease anxiety in 85%, to decrease air hunger in 76%, to comfort families in 82%, and to hasten death in 39%; in no instance was hastening death the only reason cited. The amounts of benzodiazepines and opiates averaged 2.2 mg/h of diazepam and 3.3 mg/h of morphine sulfate in the 24 hours before withholding and withdrawal of life support and 9.8 mg/h and 11.2 mg/h in the 24 hours thereafter (P less than .025 and P less than .001, respectively).

CONCLUSIONS

Large doses of sedatives and analgesics were ordered primarily to relieve pain and suffering during the withholding and withdrawal of life support, and death was not hastened by drug administration.

Molecular comparison of VP3 from bluetongue and epizootic hemorrhagic disease viruses

The complete nucleic acid sequence of gene 3 from epizootic hemorrhagic disease of deer (EHD) virus serotype 1 was determined. The 2768 bp sequence encodes a single protein that contains 899 amino acids and has a molecular weight of 103 kDa. The predicted protein sequence has 94.7% identity with EHD virus serotype 2 and greater than 77% identity with the related bluetongue viruses serotypes 1, 10 and 17 VP3 proteins. The relevance of these data to studies of recombinant DNA diagnostics and genetic relatedness is discussed.

Cytokine modulation of the interaction between bluetongue virus and endothelial cells in vitro

An in vitro model was developed to examine the interaction between endothelial cells and the host inflammatory response in bluetongue virus (BTV) infections. Whole cell enzyme-linked immunosorbent assays, a tritiated thymidine uptake assay, and a colorimetric assay of mitochondrial function were used to assess how four cytokines (interleukin-1, interleukin-2, interferon-gamma, and tumor necrosis factor-alpha) affect endothelial cell metabolism and susceptibility to BTV infection. Concurrent alterations in major histocompatibility complex (MHC) antigen expression were also examined. BTV infection suppressed target cell mitochondrial function and DNA synthesis and enhanced MHC class I expression. Interferon-gamma and tumor necrosis factor alpha suppressed viral antigen expression and were synergistic early in the infection. Interferon gamma enhanced MHC class I and induced MHC class II antigen expression in both BTV infected and uninfected endothelial cells. The other cytokines had minimal effect on endothelial cell surface antigen expression, although interleukin-1 (IL-1) did inhibit cell growth. Infected endothelial cell cultures produced interferon at 20 hours and 40 hours after infection. Electron microscopic analysis confirmed previous findings in other cell lines regarding BTV morphogenesis in endothelial cells, the putative target cell population in vivo.

A RNA virus in cells from Culicoides variipennis

A virus was detected in cells (designated CuVa) cultured from one laboratory colony of the biting midge, Culicoides variipennis. By electron microscopy (30 nm), nonenveloped, icosahedral virions arranged separately and in crystalline matrix arrays were seen in the cytoplasm but not in the nucleus of CuVa cells. Separation by 10% polyacrylamide gel electrophoresis revealed multiple bands of viral-induced double-stranded RNA. Inoculation of this virus onto different cell lines and intracranially into suckling mice revealed no detectable pathology. Immunoperoxidase staining using polyclonal antibody determined that the virus is infectious to toad cells, bovine endothelial cells, bovine kidney cells, mosquito cells, and cells (designated KC) initiated from another laboratory colony of C. variipennis. KC cells infected with this virus were coinfected with bluetongue virus with no decrease in bluetongue virus titer.

Development and optimization of a hybridization assay for epizootic hemorrhagic disease viruses

Hybridization assays for the double-stranded RNA (dsRNA) orbiviruses causing bluetongue and epizootic hemorrhagic disease are more labor-intensive and less sensitive than enzyme-linked immunosorbent assay (ELISA) and immunoperoxidase assay. Cell-culture EHD virus amplification, rapid extraction, and optimization of RNA blotting conditions were examined to increase sensitivity and decrease labor. Aldehyde RNA denaturations and nylon hybridization membranes resulted in stronger positive hybridization signals. Treatment of infected cells with protease did not increase the yield of viral RNA target. Because RNA extraction is a tedious process, a simple non-phenolic diethyl pyrocarbonate extraction procedure was developed. The sensitivity, versatility, and the reproducibility of hybridization assays are addressed.

Diagnostic complementary DNA probes for genome segments 2 and 3 of epizootic hemorrhagic disease virus serotype 1

Potential diagnostic complementary DNA (cDNA) clones of gene segments 2 and 3 from epizootic hemorrhagic disease virus serotype 1 (EHDV-1) have been produced. Individual segments of EHDV-1 were isolated, denatured with methylmercury hydroxide, and polyadenylated. The polyadenylated RNA was reverse-transcribed and self-hybridized into duplex structures, and the incomplete ends were repaired. The resulting product was then cloned into the plasmid vector pBR322, using the complementary tailing method. Two clones, 1 from segment 2 (E1-2-10) and 1 from segment 3 (E1-3-16) were isolated, colony-purified, and characterized by cDNA/RNA blot hybridization and endonuclease restriction analysis. The cDNA clones of RNA segment 3 of EHDV-1 cross hybridized with the corresponding segment of EHDV serotype 2 by results of cDNA/RNA blot hybridization, but not with RNA of bluetongue virus serotypes isolated in the United States. After cDNA/RNA dot-blot hybridization analysis of 17 EHDV field strains, the segment-2 clone was found to be serotype-specific, whereas the segment-3 clone was serogroup-specific.