Epidemiological and clinical features of visceral leishmaniasis in children in Alicante Province, Spain

BACKGROUND

Visceral leishmaniasis (VL) is endemic to the Mediterranean basin. In children, VL often presents with non-specific symptoms and can be life-threatening without proper treatment.

AIM

To describe the epidemiological and clinical features of pediatric VL in children in Alicante, Spain.

METHODS

The study included all paediatric (<15 years) cases admitted to three hospitals in the province of Alicante from May 1992 to May 2015 with diagnosis of VL (detection was either by anti-Leishmania antibodies in serology or Leishmania in blood and/or bone marrow aspirates).

RESULTS

There were 38 cases of pediatric VL (18 aged <24 months, 15 aged 24-59 months and 5 aged ≥5 years). The main symptoms were fever (97.4%), followed by pallor (75.0%) and loss of appetite (46.4%). Eighty-seven per cent of patients were anaemic (haemoglobin < 9 g/dL), 73.7% had neutropenia and 68.4% had thrombocytopenia. Before 2004, 92.3% of patients were treated with meglumine antimoniate (MA) and 7.7% with liposomal amphotericin B (LAmB); after 2004, 84% were treated with LAmB and just one (16%) with MA (p < 0.001). LAmB performed better than MA in terms of mean treatment length (7.4 days vs 25.9 days, p < 0.001), time to becoming afebrile (1.7 vs 13.7 days, p < 0.001), and length of hospital stay (10.9 vs 19.4 days, p = 0.001).

CONCLUSION

Paediatric VL in Alicante mainly affects children under five. Children aged ≤24 months present with a lower haemoglobin and white blood cell count. Treatment with LAmB reduces treatment length, time to becoming afebrile and length of hospital stay.

Current Status and Future Prospects to Achieve Foot-and-Mouth Disease Eradication in South America

South America has a favourable position with respect to foot-and-mouth disease (FMD) compared with other FMD-affected regions due to the elimination of endemic clinical presentation of the disease. South America has reached the final stage of control and aims to eradicate the disease in the region under the provisions of the Hemispheric Program for the Eradication of FMD 2011-2020 (PHEFA). This programme aims at bringing eradication to completion, thereby eliminating the pool of foot-and-mouth disease genotypes active in South America. This plan includes a regional political agreement that provides strategies and technical guidelines for the eradication of foot-and-mouth disease from South America. It incorporates knowledge and experience regarding the disease's history and its connection with the different production systems, animal movement and trade. The Pan American Foot and Mouth Disease Center has led the control and eradication programmes, providing the framework for designing national and subregional programmes that have led to significant progress in controlling the disease in South America. The current situation is the result of several factors, including the proper implementation of a national control programmes, good veterinary infrastructure in most countries and public-private participation in the process of eradicating the disease. Notwithstanding the favourable health status, there are significant challenges for the goal of eradication. At this stage, South American countries should enhance their surveillance strategies particularly through the use of target or risk-based surveys that contribute to increase the degree of sensitivity in the search for viral circulation in the context of absence of clinical occurrence of FMD.

Identification and analysis of the first 2009 pandemic H1N1 influenza virus from U.S. feral swine

The first case of pandemic H1N1 influenza (pH1N1) virus in feral swine in the United States was identified in Texas through the United States Department of Agriculture (USDA) Wildlife Services' surveillance program. Two samples were identified as pandemic influenza by reverse transcriptase quantitative PCR (RT-qPCR). Full-genome Sanger sequencing of all eight influenza segments was performed. In addition, Illumina deep sequencing of the original diagnostic samples and their respective virus isolation cultures were performed to assess the feasibility of using an unbiased whole-genome linear target amplification method and multiple sample sequencing in a single Illumina GAIIx lane. Identical sequences were obtained using both techniques. Phylogenetic analysis indicated that all gene segments belonged to the pH1N1 (2009) lineage. In conclusion, we have identified the first pH1N1 isolate in feral swine in the United States and have demonstrated the use of an easy unbiased linear amplification method for deep sequencing of multiple samples.

Identifying areas of high risk of human exposure to coccidioidomycosis in Texas using serology data from dogs

Coccidioidomycosis or Valley Fever (VF) is an emerging soil-borne fungal zoonosis affecting humans and animals. Most non-human cases of VF are found in dogs, which we hypothesize may serve as sentinels for estimating the human exposure risk. The objective of this study is to use the spatial and temporal distribution and clusters of dogs seropositive for VF to define the geographic area in Texas where VF is endemic, and thus presents a higher risk of exposure to humans. The included specimens were seropositive dogs tested at a major diagnostic laboratory between 1999 and 2009. Data were aggregated by zip code and smoothed by empirical Bayesian estimation to develop an isopleth map of VF seropositive rates using kriging. Clusters of seropositive dogs were identified using the spatial scan test. Both the isopleth map and the scan test identified an area with a high rate of VF-seropositive dogs in the western and southwestern parts of Texas (relative risk = 31). This location overlapped an area that was previously identified as a potential endemic region based on human surveys. Together, these data suggest that dogs may serve as sentinels for estimating the risk of human exposure to VF.

Degradation of foot-and-mouth disease virus during composting of infected pig carcasses

The objective of this study was to investigate the inactivation and degradation of foot-and-mouth disease (FMD) virus during composting of infected pig carcasses as measured by virus isolation in tissue culture and by real-time reverse transcriptase polymerase chain reaction (RRT-PCR). Three FMD-infected pig carcasses were composted in a mixture of chicken manure and wood shavings in a biocontainment level 3 facility. Compost temperatures had reached 50 degrees C and 70 degrees C by days 10 and 19, respectively. Under these conditions, FMD virus was inactivated in specimens in compost by day 10 and the viral RNA was degraded in skin and internal organ tissues by day 21. In comparison, at ambient temperatures close to 20 degrees C, FMD virus survived to day 10 in the skin tissue specimen from the pig that had the highest initial level of viral RNA in its tissues and the viral RNA persisted to day 21. Similarly, beta-actin mRNA, tested as a PCR control, persisted to day 21 in specimens held at ambient temperatures, but it was degraded in the remnants of tissues recovered from compost on day 21. Results from this study provide evidence that composting could be used for safe disposal of pig carcasses infected with FMD virus.

Expression and purification of an anti-Foot-and-mouth disease virus single chain variable antibody fragment in tobacco plants

Low-cost recombinant antibodies could provide a new strategy to control Foot-and-mouth disease virus (FMDV) outbreaks by passive immunization of susceptible animals. In this study, a single chain variable antibody fragment (scFv) recognizing FMDV coat protein VP1 was expressed in transgenic tobacco plants. To enhance the accumulation of scFv protein, the codon-usage of a murine hybridoma-derived scFv gene was adjusted to mimic highly expressed tobacco genes and fused to an elastin-like polypeptide (ELP) tag. This scFv-ELP fusion accumulated up to 0.8% of total soluble leaf protein in transgenic tobacco. To recover scFv-ELP protein from the leaf extract, a simple and scalable purification strategy was established. Purified scFv-ELP fusion was cleaved to separate the scFv portion. Finally, it was shown that the purified scFv proteins retained their capacity to bind the FMDV in the absence or presence of ELP fusion.

Volatile and sensory profile of organic red wines produced by different selected autochthonous and commercial Saccharomyces cerevisiae strains

Organic wines were produced at pilot scale to select the best autochthonous and commercial yeast strains to obtain wines with high organoleptic qualities. We tested the behaviour of five S. cerevisiae yeast strains and determined their volatile composition and organoleptic characteristics by sensory analysis. A total of 51 volatile compounds were quantified in the wines produced. The concentration of most of the volatile compounds was significantly influenced depending on which yeast strain was inoculated. The differences observed in the volatile composition of the wines appear to be quantitative rather than qualitative. In general, acetals were the most abundant group of volatile compounds in all the samples studied, followed by alcohols without ethanol. The highest contents of volatile compounds were found in two of the wines produced by autochthonous yeast strains. The results obtained in the sensory analysis suggest that autochthonous yeast produced wines of higher organoleptic quality because this sample gave the highest value for the general impression attribute.

Characterization of avian influenza virus isolates submitted to the National Centre for Foreign Animal Disease between 1997 and 2001

The National Centre for Foreign Animal Disease (NCFAD) in Winnipeg, Manitoba, is the Canadian Food Inspection Agency's (CFIA) newest high biocontainment laboratory. One of the functions of the NCFAD is to serve as a national reference laboratory for avian influenza. Between 1997 and 2001, 15 avian influenza virus isolates were characterized. These isolates originated from domestic poultry, imported caged birds held in quarantine, and wild birds. Diagnostic specimens were submitted to the NCFAD by CFIA field veterinarians, provincial veterinary diagnostic laboratories, and veterinary colleges. Characterization of isolates included the determination of H and N subtypes: H1, H6, H7, and H10 subtypes were isolated from domestic poultry; H3, H4, and three H13 viruses were isolated from water fowl, and six H3 viruses were isolated from caged birds being held in import quarantine. Selected isolates were characterized with respect to their pathogenic potential by intravenous inoculation of 4-to-6-wk-old chickens. A molecular-based protocol was used to assess the pathogenicity of one H7 isolate. During this period, work was also carried out toward validating our molecular pathotyping protocol for avian influenza viruses with H5 and H7 hemagglutinin subtypes.

Pathogenicity of a Ratite-Origin Influenza A H5 Virus in Ostriches (Struthio camelus)

Ostriches were inoculated with a highly pathogenic avian influenza (HPAI) virus of ratite origin, A/emu/Texas/39924/93 (H5N2) done clB. The aim of this study was to evaluate the pathogenicity of this isolate for ostriches and to assess the ability of routine virologic and serologic tests to detect infection. Avian influenza virus (AIV) was isolated from tracheal swabs from 2 to 12 days postinfection and from cloacal swabs from 3 to 10 days postinfection. AIV was also isolated from a wide range of tissues. Birds seroconverted as early as 7 days postinfection. This study indicates that HPAI virus of ratite origin replicates extensively in infected ostriches without causing significant clinical disease or mortality.

Use of the reverse transcription polymerase chain reaction (RT-PCR) for the rapid diagnosis of foot and mouth disease in South America

Foot and mouth disease (FMD) is a limiting factor for the economic progress of the animal industry in South America. The presence of the disease results in the imposition of national and international sanitary barriers to animals and animal products, and, most especially, a reduction in the availability of protein from animal origin and in income. Rapid and accurate identification of infected animals, those with either clinical or subclinical disease as well as with persistent infection, is essential for maintaining an efficient eradication programme. The polymerase chain reaction was used to rapidly identify infected animals. With a primer set that corresponds to a conserved region of the 3D sequence of the viral genome, it was possible to amplify, regardless of the serotype, 116 strains of FMD virus, of which 109 were strains collected from outbreaks of FMD throughout South America from 1945 to the most recent outbreaks in 2000/2001. The PCR technique should be of considerable value in facilitating the diagnosis of FMD in South America. where laboratory resources are limited and a rapid response is needed, particularly in areas where national programmes for controlling or eradicating the disease are being implemented.

Duration of bluetongue viremia in experimentally infected American bison

Six yearling American bison (Bison bison bison) bulls and one yearling ewe (Ovis aries) were inoculated intradermally and subcutaneously with 2 x 10(5) plaque forming units (pfu) of bluetongue (BT) virus serotype 11. Two uninoculated yearling bison bulls served as negative controls. Blood samples were collected for serology and virus isolation on 0, 4, 7, 11 and 14 days post-inoculation (dpi) and every 2 wk thereafter to 127 dpi. Every 4 wk a new ewe was inoculated with a pooled sample of whole blood from the six infected bison, and each sheep was monitored for 28 days for clinical signs of BT and seroconversion. Bluetongue viremia was detected in all six inoculated bison starting at 4 to 28 dpi and was no longer detectable from 42 dpi onward. Pooled blood samples collected at 28, 56, 84 and 112 dpi from the six infected bison were not infectious for sheep. The six infected bison seroconverted by 11 to 28 dpi on a competitive enzyme-linked immunosorbent assay and by 28 dpi on the serum neutralization test, and all remained seropositive thereafter. No clinical signs or lesions attributable to BT were observed in the infected bison or controls. There was evidence that a small amount of epizootic hemorrhagic disease virus type 2 had been present in the BT virus inoculum; reasons are given for concluding that this did not affect the results of the BT study.

Serologic evidence of influenza A infection in marine mammals of arctic Canada

A serologic survey of influenza A antibodies was undertaken on 1,611 blood samples from five species of marine mammals collected from Arctic Canada from 1984-98. Sampling was done in 24 locations throughout the Canadian Arctic encompassing Sachs Harbor (72 degrees N, 125 degrees W), Northwest Territories in the west to Loks Land (63 degrees N, 64 degrees W), Nunavut in the east, to Eureka (80 degrees N, 86 degrees W), Nunavut in the north to Sanikiluaq (56 degrees N, 79 degrees W), Nunavut in the south. A competitive ELISA using a monoclonal antibody (Mab) against influenza A nucleoprotein (NP) was used. Five of 418 (1.2%) belugas (Delphinapterus leucas) and 23 of 903 (2.5%) ringed seals (Phoca hispida) were serologically positive. None of the 210 walruses (Odobenus rosmarus rosmarus), 76 narwhals (Monodon monoceros) and four bowhead whales (Balaena mysticetus) had detectable antibodies to influenza A. Positive belugas were identified from communities on southeast Baffin Island while positive ringed seals came from communities in the eastern, western and high Arctic. Virus isolation attempts on lung tissue from a seropositive beluga were unsuccessful. We believe that influenza A infection in marine mammals is sporadic, the infection is probably self-limiting, and it may not be able to be maintained in these animals. Although the predominant hemagglutinin (H) type was not determined and therefore the pathogenicity of the strains to humans is unknown, the hunting and consumption of marine mammals by the Inuit, may put them at risk for influenza A infection.

Application of competitive enzyme-linked immunosorbent assay for the serologic diagnosis of classical swine fever virus infection

A competitive enzyme-linked immunosorbent assay (C-ELISA), based on a truncated E2 recombinant protein of the Alfort/187 strain of classical swine fever virus (CSFV) and a specific monoclonal antibody M1669, was evaluated using 2,000 sera from clinically healthy pigs in Canada (a CSFV-free country) and sera from experimentally infected pigs. The relative specificity and sensitivity of the C-ELISA were 100% and 86%, respectively, at a cutoff of 25% inhibition using negative and positive pig sera, as defined by the neutralizing peroxidase-linked assay (NPLA). A kappa value of 0.91 was obtained, indicating an excellent level of agreement between the NPLA and the C-ELISA. When sera from 120 infected pigs were used in the test at > or = 21 days postinfection, the sensitivity of the C-ELISA and the kappa value increased to 97% and 0.98, respectively. This C-ELISA will be useful when a large number of samples must be tested, as could occur during a disease outbreak or for surveillance or prevalence studies.

Development of an immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay for detection of equine and swine IgM antibodies to vesicular stomatitis virus

An immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (MC-ELISA) was developed for the detection of primary infection of vesicular stomatitis virus (VSV) in equine and swine sera. The test was based on the use of biotinylated sheep antibodies against equine or swine IgM molecules bound to a streptavidin-coated ELISA plate. The captured IgM antibodies were detected by application of antigens prepared from the New Jersey and the Indiana VSV serotypes (VSV-NJ and VSV-IN, respectively) and mouse polyclonal antibodies against VSV-NJ and VSV-IN. The MC-ELISA was compared to a competitive ELISA (C-ELISA) and the standard microtiter serum neutralization (MTSN) assay by testing serum samples from horses and pigs experimentally infected with VSV-NJ or VSV-IN. The MC-ELISA detected specific homologous IgM antibodies from equine and swine sera as early as 5 and 4 days postinfection (DPI), respectively, and as late as 35 DPI. The MTSN test also detected antibodies as early as 5 DPI and as late as 160 DPI. In a similar fashion, the C-ELISA detected antibodies from 6 to 7 DPI and as late as 160 DPI. These results demonstrated that the MC-ELISA is a useful test for serodiagnosis of primary VSV infection in horses and pigs.

Incursion of epizootic hemorrhagic disease into the Okanagan Valley, British Columbia in 1999

In September 1999, unusually high mortality rates in white-tailed deer and California bighorn sheep occurred in the southern Okanagan Valley. Necropsy and histopathologic findings were compatible with epizootic hemorrhagic disease (EHD); the presence of virus was not demonstrated. Subsequent serologic and polymerase chain reaction assays on sentinel cattle suggested an EHD virus incursion.

Development and evaluation of an IgM-capture ELISA for detection of recent infection with bluetongue viruses in cattle

An IgM-capture enzyme-linked immunosorbent assay (ELISA) was developed for the detection of recent infection of bluetongue virus (BTV) in cattle. The test is based on the use of biotinylated capture anti-bovine IgM antibodies bound to a streptavidin-coated ELISA plate. The captured IgM antibodies were detected by application of BTV VP7 antigen and a VP7 antigen-specific monoclonal antibody. The IgM-capture ELISA was compared with the competitive ELISA by testing serum samples from groups of calves infected experimentally with five USA and 19 South Africa serotypes of BTV. The IgM-capture ELISA was able to detect bovine anti-VP7 antibodies from all animals infected with the 24 BTV serotypes at 10 days post-infection, whereas the competitive ELISA was not. When the detectable IgM diminished after 40 days post-infection by the IgM-capture ELISA, the IgG anti-VP7 antibodies remained high. The IgM-capture ELISA is sensitive and can be applied for the detection of recent infection of BTV in cattle.

Development of a competitive ELISA using a truncated E2 recombinant protein as antigen for detection of antibodies to classical swine fever virus

The sequence encoding a truncated E2 glycoprotein of the Alfort/187 strain of classical swine fever virus (CSFV) was expressed in Escherichia coli using the pET expression system and the recombinant product purified by Ni-NTA agarose affinity chromatography. The antigenicity of this recombinant protein was demonstrated by immunoblot using anti- CSFV-specific antibodies. A monoclonal antibody was produced against the truncated E2 protein and used as competitor in an ELISA for the detection of antibodies to CSFV. Specific antibodies were demonstrated by competitive ELISA (C-ELISA) as early as 21 days post-infection (dpi) in experimentally infected pigs. Seroconversion was demonstrated by C-ELISA and neutralising peroxidase-linked assay (NPLA) in all infected animals by 4 weeks. No cross-reaction with antibodies to bovine viral diarrhoea virus (BVDV) was seen in the C-ELISA using sera from experimentally infected pigs. The C-ELISA is not intended as a substitute for the NPLA. However, it is expected it will be useful for monitoring and prevalence studies. It will also assist in testing a large number of samples in the event of an outbreak.

Isolation of Newcastle disease virus and Salmonella typhimurium from the brain of double-crested cormorants (Phalacrocorax auritus)

Avian paramyxovirus type 1 (Newcastle disease virus) and Salmonella typhimurium were isolated from the brain and lung tissues of double-crested cormorants (Phalacrocorax auritus) from Lac Canard, Alberta, Canada. More than 100 birds died during this outbreak in 1999. Affected birds presented signs of central nervous system disease characterized by unilateral wing and leg paralysis. Other geographic locations in the provinces of Alberta and Saskatchewan have reported cases of cormorants suffering from diseases with signs compatible with Newcastle disease. The virus isolated in the 1999 outbreak was characterized as mesogenic. These findings suggest that other pathogens, like S. typhimurium, may influence the clinical presentation of disease caused by mesogenic strains of Newcastle disease virus in cormorants.

Deletions of structural glycoprotein E2 of classical swine fever virus strain alfort/187 resolve a linear epitope of monoclonal antibody WH303 and the minimal N-terminal domain essential for binding immunoglobulin G antibodies of a pig hyperimmune serum

The major structural glycoprotein E2 of classical swine fever virus (CSFV) is responsible for eliciting neutralizing antibodies and conferring protective immunity. The current structural model of this protein predicts its surface-exposed region at the N terminus with a short stretch of the C-terminal residues spanning the membrane envelope. In this study, the N-terminal region of 221 amino acids (aa) covering aa 690 to 910 of the CSFV strain Alfort/187 E2, expressed as a fusion product in Escherichia coli, was shown to contain the epitope recognized by a monoclonal antibody (WH303) with affinity for various CSFV strains but not for the other members of the Pestivirus genus, bovine viral diarrhea virus (BVDV) and border disease virus (BDV). This region also contains the sites recognized by polyclonal immunoglobulin G (IgG) antibodies of a pig hyperimmune serum. Serial deletions of this region precisely defined the epitope recognized by WH303 to be TAVSPTTLR (aa 829 to 837) of E2. Comparison of the sequences around the WH303-binding site among the E2 proteins of pestiviruses indicated that the sequence TAVSPTTLR is strongly conserved in CSFV strains but highly divergent among BVDV and BDV strains. These results provided a structural basis for the reactivity patterns of WH303 and also useful information for the design of a peptide containing this epitope for potential use in the detection and identification of CSFV. By deletion analysis, an antigenic domain capable of reacting with pig polyclonal IgG was found 17 aa from the WH303 epitope within the N-terminal 123 residues (aa 690 to 812). Small N- or C-terminal deletions introduced into the domain disrupt its reactivity with pig polyclonal IgG, suggesting that this is the minimal antigenic domain required for binding to pig antibodies. This domain could have eliminated or reduced the cross-reactivity with other pestiviruses and may thus have an application for the serological detection of CSFV infection; evaluation of this is now possible, since the domain has been expressed in E. coli in large amounts and purified to homogeneity by chromatographic methods.

Isolation and identification of bluetongue virus

Bluetongue virus (BTV) is an arthropod-borne orbivirus that infects sheep, wild ruminants and occasionally cattle. Detection and specific identification of BTV is a multistep process. The first step involves the isolation of the virus from the animal's blood or other tissues, followed by inoculation of embryonating chicken eggs (ECE). After the virus has been amplified in ECE, it is passaged into BHK-21 cell culture for subsequent replication and identification. The virus is then amplified further and identified in microtiter plates by the immunoperoxidase assay using a group specific monoclonal antibody. Finally, the viral isolate is typed by a virus neutralization test.

Velogenic Newcastle disease in imported caged birds

Velogenic Newcastle disease was diagnosed in pet birds intended for importation into Canada. Virological and histopathological examination confirmed the presence of the disease. The group of birds was denied entry into Canada. Similar birds illegally imported are a potential source of velogenic Newcastle disease virus and are a threat to domestic poultry.

Incursion of bluetongue virus into the Okanagan Valley, British Columbia

Bluetongue virus was isolated from a sentinel herd in British Columbia. Virus isolation was by intravenous inoculation of embryonated chicken eggs and subculture in BHK-21 cells. The cytopathic agent was identified as bluetongue virus by electron microscopy and the immunoperoxidase test. The serotype was identified as serotype 11 by virus neutralization.

Development and evaluation of a novel antigen capture assay for the detection of classical swine fever virus antigens

An antigen-capture enzyme immunoassay (EIA) was developed to detect classical swine fever virus (CSFV) antigen directly from 10% w/v tissue suspension. The assay, based on the sandwich principle, uses a biotinylated monoclonal antibody bound to streptavidin-coated microplates as the capture system and a swine anti-CSFV antibody and rabbit anti-swine HRPO-conjugate as the detector system. The antigen-capture EIA was compared with conventional virus isolation and polymerase chain reaction (PCR) for detection of CSFV in tissues. The ability of the antigen-capture EIA to discriminate classical swine fever (CSF) from bovine viral diarrhea and African swine fever viruses was also tested. The assay was shown to detect 21 different strains of CSFV and was unreactive with tissues from uninfected animals. Signal to noise (S/N) ratios were calculated from the EIA absorbance values. Readings from samples positive by virus isolation (n = 47) averaged a S/N ratio of 5.34. In contrast, samples negative by virus isolation (n = 96) demonstrated a mean S/N ratio of 0.16. At S/N cut-off value of 1.0, all samples that yield virus isolation and PCR negative result were negative in the antigen-capture EIA. Compared with virus propagation in tissue culture using PK15 cells (followed by indirect peroxidase assay detection) and PCR, the EIA had a specificity of 98.7% and a sensitivity of 91.4%. The EIA is simple, can be performed in 4 h and lends itself to automation for screening of tissues sample from pigs suspected of CSFV infection.

Differentiation of infectious laryngotracheitis virus strains by polymerase chain reaction

Oligonucleotide primers derived from infectious laryngotracheitis virus (ILTV) DNA clones of vaccine and virulent strains were used to develop a polymerase chain reaction (PCR) for the identification and differentiation of ILTV strains. The PCR followed by restriction endonuclease analysis was used to group four strains of ILTV. A 458-bp sequence that for the LT-IVAX ILTV strain contains a unique BamHI site was amplified by PCR and digested with BamHI restriction endonuclease. From the sizes of the resultant DNA fragments the virulent strain was distinguished from the three low virulence strains.

Molecular cloning and restriction enzyme mapping of avian adenovirus type 8 DNA

Avian adenovirus (AAV) type 8 was cultured in an avian hepatoma cell line designated CH-SAH and the viral DNA extracted and purified. Restriction enzyme analysis of viral DNA using the endonucleases ApaI, EcoRI, HindIII, KpnI, NotI, SpeI, StuI and XbaI was carried out, and fragments representing the entire genome were cloned. According to the restriction enzyme fragments, the size of the AAV type 8 genome was calculated to be 44.7 kb. Subcloning of viral DNA fragments and hybridization studies using selected viral DNA fragments facilitated the construction of the physical map of AAV type 8 DNA.

Serologic diagnosis of caprine arthritis-encephalitis by ELISA with two recombinant proteins in a parallel testing format

A scheme for screening sera for antibodies to caprine arthritis-encephalitis virus (CAEV) was evaluated for its ability to identify positive and negative samples in a population with heterogeneous risk factors, using the criteria of sensitivity, specificity and positive predictive value. Five hundred caprine serum samples were tested using a transmembrane recombinant-based ELISA. Those that gave positive results were considered positive, while those with equivocal or negative results were retested with a core recombinant protein-based ELISA. Equivocal results after the second test were considered indeterminate and retesting is advised. Using this approach, a sensitivity, specificity and positive predictive value of 98.8%, 97.2% and 98.6% were obtained. These values are superior to those obtained by these tests used individually. The high sensitivity, specificity and predictive value of this new scheme of CAEV screening make it an attractive addition to any control or eradication program.

Bacterial expression of the caprine arthritis-encephalitis virus gag and env proteins and their use in enzyme-linked immunosorbent assay

The core protein and the transmembrane protein, encoded for the structural genes gag and env, respectively, of caprine arthritis-encephalitis virus were amplified by use of polymerase chain reaction, cloned into a pGEX-2T vector, and expressed in Escherichia coli as fusion proteins with the glutathione S-transferase at their C-terminus. The recombinant proteins were purified and evaluated by use of an ELISA. Sera from 269 goats were tested, and the results were compared with those obtained by use of immunoblot analysis. When results from both recombinant ELISA (r-ELISA) were compared, it appeared that the transmembrane glycoprotein was more immunoreactive than the core protein, because it was recognized by a higher percentage of sera from infected goats. When results of the 2 ELISA (p28 r-ELISA and p40 r-ELISA) were combined in parallel, they were comparable to those of the immunoblot test, with sensitivity of 100% and specificity of 98.3%. It was also found that use of both r-ELISA makes it possible to compare the variable immunoreactivity against gag and env viral antigens, which may be correlated with the disease state. The r-ELISA, using core and transmembrane proteins, appears to be highly sensitive and specific for detection of antibodies against caprine arthritis-encephalitis virus.

Chemiluminescent detection of caprine arthritis encephalitis virus with a PCR-generated single stranded nonradiolabelled probe

A 814-bp digoxigenin-labelled single stranded DNA probe was produced and utilized in slot-blot hybridization for detection of caprine arthritis encephalitis virus (CAEV) in goat synovial membrane (GSM) cell culture infected with CAEV. The sensitivity of a PCR-generated probe was compared with a random primer labelled probe. The probe with digoxigenin-dUTP incorporated in the PCR reaction mixture was more sensitive for RNA detection than the random primer probe and it was much simpler to use. The probe was applied for detection of CAEV by blot blot hybridization in peripheral blood mononuclear cells (PBMC) and macrophage cultures obtained from naturally infected goats. This technique was not sufficiently sensitive to detect the viral nucleic acid directly from PBMC or cultured macrophages. When macrophages were cultured in vitro and then cocultured with susceptible GSM cells, samples gave a positive signal in the slot-blot hybridization technique. The use of slot-blot RNA hybridization permits more convenient and rapid confirmation of CAEV isolation in susceptible cells than the conventional identification by syncytia formation.