Co-infection with different serotypes of FMDV in vaccinated cattle in Southern Egypt.

During 2015-2016 period, an outbreak of foot-and-mouth disease virus (FMDV) was observed in cattle in four governorates of the upper of Egypt. The infection was extended to the vaccinated cattle. A total of 54 mouth swabs and serum samples were collected from vaccinated cattle for serological and virological investigation. The typical clinical signs of FMDV infection were observed in all cattle under investigation. All samples were positive for FMDV using molecular methods, while the serological method showed 85% positive of tested samples. Typing of FMDV-positive samples using serotype-specific primers showed that 51.8% of samples were serotype O, 9.2% were serotype A, and 18.5% were SAT 2. Surprisingly, co-infections of serotypes A/SAT 2 (12.9%) and O/SAT 2 (7.4%) were also detected. By geographical location, the 3 serotypes A, O, and SAT2 were detected in all four governorates. The phylogenetic assessment of the detected viruses showed that two distinct groups of FMDV serotype O of East Africa-3 (EA-3) topotype were most closely related to circulating viruses in Sudan, as well as FMDV strains belonging to the topotype VII of serotype SAT 2. The detected SAT 2 strains clustered in separate clades in topotype VII, indicating new incursions. The VP1 signatures and protein sequences of some characterized viruses were analyzed. Multiple mutations were detected in VP1. Therefore, to enhance the control of FMD in Egypt, we recommend establishing an active surveillance system to characterize newly emerging virus strains/serotypes and subsequently updating vaccine strains.

Development and laboratory evaluation of a lateral flow device (LFD) for the serodiagnosis of Theileria annulata infection.

Several DNA-based and serological tests have been established for the detection of Theileria annulata infection, including polymerase chain reaction, reverse line blot and loop-mediated isothermal amplification, indirect enzyme-linked immunosorbent assay (ELISA), and competitive ELISA. In this study, we have applied knowledge from the development and application of a recombinant protein-based indirect ELISA and competitive ELISA to establish a rapid test for point-of-care diagnosis of T. annulata infection in the field to be used by the veterinarian. For the development of a lateral flow test, the recombinantly expressed T. annulata surface protein (TaSP) was applied as the test antigen and anti-TaSP antiserum as the control line. TaSP antigen conjugated to colloidal gold particles was used as the detection system for visualization at the test line for the binding of anti-TaSP antibody present in the serum of infected animals. The developed test specifically detected antibodies in the serum of animals experimentally infected with T. annulata and showed no cross-reactivity with serum from animals infected with other tested bovine pathogens (Trypanosoma brucei, Anaplasma marginale, Babesia bigemina, Babesia bovis, and Theileria parva). Testing of field samples was compared to results obtained by other serological tests, resulting in a sensitivity and specificity of 96.3% and 87.5% compared to indirect fluorescence antibody test, 98.7% and 81.8% compared to indirect ELISA, and 100% and 47.6% compared to competitive ELISA. In conclusion, a rapid test for the detection of T. annulata infection (T. annulata lateral flow device, Ta-LFD) has been developed, which is easy to perform, delivers results to be read by the naked eye within 10 min, and is suitable for the detection of infection in field samples.

Development and laboratory validation of a lateral flow device for the detection of foot-and-mouth disease virus in clinical samples.

A lateral flow device (LFD) for the detection of all seven serotypes of foot-and-mouth disease virus (FMDV) was developed using a monoclonal antibody (Mab 1F10) shown to be pan-reactive to FMDV strains of each serotype by ELISA. The performance of the LFD was evaluated in the laboratory on suspensions of vesicular epithelia (304 positive and 1003 negative samples) from suspected cases of vesicular disease collected from 86 countries between 1965 and 2008 and negative samples collected from healthy animals. The diagnostic sensitivity of the LFD for FMDV was similar at 84% compared to 85% obtained by the reference method of antigen ELISA, and the diagnostic specificity of the LFD was approximately 99% compared to 99.9% for the ELISA. The device recognized FMDV strains of wide diversity of all seven serotypes but weaker reactions were often evident with those of type SAT 2, several viruses of which were not detected. Reactions with the viruses of swine vesicular disease and vesicular stomatitis that produce clinically indistinguishable syndromes in pigs and cattle, did not occur. The test procedure was simple and rapid, and typically provided a result within 1-10min of sample addition. Simple homogenizers that could be used in field conditions for preparing epithelial suspensions were demonstrated to be effective for LFD application. These data illustrate the potential for the LFD to be used next to the animal in the pen-side diagnosis of FMD and for providing rapid and objective support to veterinarians in their clinical judgment of the disease.

Evaluation of a novel proximity ligation assay for the sensitive and rapid detection of foot-and-mouth disease virus.

A novel proximity ligation assay (PLA) using a pan-serotype reactive monoclonal antibody was developed and evaluated for the detection of foot-and-mouth disease virus (FMDV) in clinical samples collected from field cases of disease. The FMDV-specific PLA was found to be 100 times more sensitive for virus detection than the commonly used antigen capture-ELISA (AgELISA). As few as five TCID50 were detected in individual assays, which was comparable with the analytical sensitivity of real-time RT-PCR. Although this assay was capable of detecting diverse isolates from all seven FMDV serotypes, the diagnostic sensitivity of the PLA assay was lower than real-time RT-PCR mainly due to a failure to detect some SAT 1, SAT 2 and SAT 3 FMDV strains. In conclusion, this new PLA format has high analytical sensitivity for the detection of FMDV in clinical samples and may prove valuable as a rapid and simple tool for use in FMD diagnosis.

Assessment of the First Commercial ELISA Kit for the Diagnosis of Theileria annulata.

The present study assesses the efficacy of SVANOVIR Theileria annulata-Ab, the first commercial ELISA kit for the diagnosis of Theileria annulata infection in cattle based on a recombinant protein known as T. annulata surface protein (TaSp). As a reference test, a polymerase chain reaction (PCR) assay depending on T. annulata merozoite surface antigen (Tams-1) was applied. A total of 468 blood samples as well as serum samples were randomly collected from cattle and tested in the PCR as well as in the ELISA developed in this study. Moreover, all samples were also analyzed by conventional Giemsa-stained blood smear. The results of this study revealed a good correlation between the results obtained by PCR and the ELISA, whereas all PCR positive samples scored correctly positive in the ELISA and 73 of the 125 PCR negative samples scored correctly negative. Taken together, a sensitivity of 91.25% and a specificity of 78.4% were recorded, when compared to the PCR data. In conclusion, the SVANOVIR Theileria annulata-Ab is a suitable diagnostic assay for use in the diagnosis and epidemiological surveys of Theileria annulata infection in chronic and carrier animals.

Cytosolic thymidine kinase is a specific histopathologic tumour marker for breast carcinomas.

Thymidine kinase 1 (TK1), an enzyme involved in the synthesis of precursors for DNA, and thus proliferation dependent, has been suggested as a good tumour marker. We have recently developed poly/monoclonal antibodies against TK1, which proved useful for diagnostics in both serum and immunohistochemistry of cancer patients. The anti-TK1 monoclonal antibodies (mAbs) 1D11 and 1E3 were characterized by Western blot, immunoprecipitation and flow cytometry. TK1 mAbs and Ki-67 mAb were then used for immunohistochemistry staining of tumour sections from 54 patients with ductal infiltrated breast carcinoma. Results showed the relative number of patients with positively stained tumours for TK1 (mAb 1D11) and for Ki-67 (mAb MIB-1) were 47 and 41%, respectively, significantly related (p=0.007). Combination of TK1 mAbs 1D11 and 1E3 increased this number to 56%, due to detection of a significantly higher number of patients with grade 2 tumours. Patients with stage II and grade 2 tumours showed significantly higher TK1 staining when compared to stage I and grade 1. Ki-67 staining was significantly higher in stage III and grade 3. The tumours only stained for TK1 represented higher stages and grades, while tumours staining only for Ki-67 were of lower stages and grades. Combining TK1 and Ki-67 increased the number of patients with positively stained tumours to 69%. In conclusion, TK1 is a reliable marker for identification of patients with grade 2 tumours. The highest number of patients with positively stained tumours were obtained when both TK1 and Ki-67 markers were used.

Development and laboratory evaluation of two lateral flow devices for the detection of vesicular stomatitis virus in clinical samples.

Two lateral flow devices (LFD) for the detection of vesicular stomatitis (VS) virus (VSV), types Indiana (VSV-IND) and New Jersey (VSV-NJ) were developed using monoclonal antibodies C1 and F25VSVNJ-45 to the respective VSV serotypes. The performance of the LFDs was evaluated in the laboratory on suspensions of vesicular epithelia and cell culture passage derived supernatants of VSV. The collection of test samples included 105 positive for VSV-IND (92 vesicular epithelial suspensions and 13 cell culture antigens; encompassing 93 samples of subtype 1 [VSV-IND-1], 9 of subtype 2 [VSV-IND-2] and 3 of subtype 3 [VSV-IND-3]) and 189 positive for VSV-NJ (162 vesicular epithelial suspensions and 27 cell culture antigens) from suspected cases of vesicular disease in cattle and horses collected from 11 countries between 1937 and 2008 or else were derived from experimental infection and 777 samples that were either shown to be positive or negative for foot-and-mouth disease (FMD) virus (FMDV) and swine vesicular disease virus (SVDV) or else collected from healthy cattle or pigs and collected from 68 countries between 1965 and 2011. The diagnostic sensitivity of the VSV-IND (for reaction with VSV-IND-1) and VSV-NJ LFDs was either similar or identical at 94.6% (VSV-IND) and 97.4% (VSV-NJ) compared to 92.5% and 97.4% obtained by the reference method of antigen ELISA. The VSV-IND LFD failed to react with viruses of VSV-IND-2 and 3, while the VSV-NJ device recognized all VSV-NJ virus strains. The diagnostic specificities of the VSV-IND and VSV-NJ LFDs were 99.1% and 100, respectively, compared to 99.6% and 99.8% for the ELISA. Reactions with FMDV which can produce indistinguishable syndromes clinically in cattle, pigs and sheep and SVDV (vesicular disease in pigs) did not occur. These data illustrate the potential for the LFDs to be used next to the animal for providing rapid and objective support to veterinarians in their clinical judgment of vesicular disease and for the subtype (VSV-IND-1) and type-specific (VSV-NJ) pen-side diagnosis of VS and differential diagnosis from FMD.

Evaluation of a blocking ELISA for the detection of antibodies against Lawsonia intracellularis in pig sera.

BACKGROUND: Lawsonia intracellularis is a common cause of chronic diarrhoea and poor performance in young growing pigs. Diagnosis of this obligate intracellular bacterium is based on the demonstration of the microbe or microbial DNA in tissue specimens or faecal samples, or the demonstration of L. intracellularis-specific antibodies in sera. The aim of the present study was to evaluate a blocking ELISA in the detection of serum antibodies to L. intracellularis, by comparison to the previously widely used immunofluorescent antibody test (IFAT). METHODS: Sera were collected from 176 pigs aged 8-12 weeks originating from 24 herds with or without problems with diarrhoea and poor performance in young growing pigs. Sera were analyzed by the blocking ELISA and by IFAT. Bayesian modelling techniques were used to account for the absence of a gold standard test and the results of the blocking ELISA was modelled against the IFAT test with a "2 dependent tests, 2 populations, no gold standard" model. RESULTS: At the finally selected cut-off value of percent inhibition (PI) 35, the diagnostic sensitivity of the blocking ELISA was 72% and the diagnostic specificity was 93%. The positive predictive value was 0.82 and the negative predictive value was 0.89, at the observed prevalence of 33.5%. CONCLUSION: The sensitivity and specificity as evaluated by Bayesian statistic techniques differed from that previously reported. Properties of diagnostic tests may well vary between countries, laboratories and among populations of animals. In the absence of a true gold standard, the importance of validating new methods by appropriate statistical methods and with respect to the target population must be emphasized.

Development and laboratory evaluation of a lateral flow device for the detection of swine vesicular disease virus in clinical samples.

A lateral flow device (LFD) for the detection of swine vesicular disease (SVD) virus (SVDV) and differential diagnosis from foot-and-mouth disease (FMD) was developed using a monoclonal antibody (Mab C70). The performance of the LFD was evaluated in the laboratory on suspensions of vesicular epithelia and cell culture passage derived supernatants of SVDV and porcine teschovirus (enterovirus; PEV). The collection of test samples included 157 which were positive for SVDV (84 vesicular epithelial suspensions and 73 cell culture antigens) from suspected cases of vesicular disease in pigs collected from 14 countries between 1966 and 2008 and 663 samples which were either shown to be negative for SVDV and FMD virus (FMDV) or else collected from healthy pigs or demonstrated to be positive for FMDV, PEV or vesicular exanthema (VEV) and collected from 16 countries between 1965 and 2008 or else were derived from experimental animals. Three further samples containing vesicular stomatitis virus (VSV) were also tested. The diagnostic sensitivity of the LFD for SVDV was similar at 82% compared to 86% obtained by the reference method of antigen ELISA, and the diagnostic specificity was 100% compared to 99.7% for the ELISA. The device recognized virus strains of each of the known genotypes of the sole SVDV serotype. Reactions with FMDV, VEV, VSV and PEV which can produce clinically indistinguishable syndromes in pigs, did not occur. These data illustrate the potential for the LFD to be used next to the animal for providing rapid and objective support to veterinarians in their clinical judgment of vesicular disease in pigs and for the specific pen-side diagnosis of SVD and differential diagnosis from FMD.

Development and laboratory validation of a lateral flow device for the detection of serotype SAT 2 foot-and-mouth disease viruses in clinical samples.

A lateral flow device (LFD) for the detection of foot-and-mouth disease virus (FMDV) of the SAT 2 serotype was developed using a monoclonal antibody (Mab 2H6). The performance of the LFD was evaluated in the laboratory on suspensions of vesicular epithelia: 305 positive for FMDV type SAT 2 from suspected cases of vesicular disease collected from 30 countries and 1002 samples shown to be negative for FMDV type SAT 2 collected from 67 countries between 1968 and 2008. The diagnostic sensitivity of the LFD for FMDV type SAT 2 was higher at 88% compared to 79% obtained by the reference method of antigen ELISA, and the diagnostic specificity of the LFD was approximately 99% compared to 100% for the ELISA. The device recognized FMDV strains of wide diversity within the FMDV SAT 2 serotype and gave a superior performance for their detection compared to the 1F10 LFD which had been developed previously and shown to perform less well for the detection of FMDVs of this particular serotype. Reactions in the SAT 2 2H6 LFD with the viruses of other FMDV serotypes and swine vesicular disease (which produces a clinically indistinguishable syndrome in pigs), did not occur. These data illustrate the potential for the LFD to be employed to complement the 1F10 device next to the animal in the pen-side diagnosis of FMD, for providing rapid and objective support to veterinarians in their clinical judgment of the disease and for specific confirmation of a FMDV type SAT 2 infection.

A microsphere-based immunoassay for rapid and sensitive detection of bovine viral diarrhoea virus antibodies.

This study describes a novel blocking microsphere-based immunoassay for highly sensitive and specific detection of antibodies against bovine viral diarrhoea virus (BVDV). The intra- and inter-assay variability are 4.9% and less than 7%, respectively, and variability of bead conjugations is less than 6.6%. The diagnostic performance of the assay was evaluated by testing a total of 509 serum samples. Based on a negative/positive cut-off value of 30.3%, the assay has a sensitivity of 99.4% and a specificity of 98.3% relative to ELISA. The new microsphere immunoassay provides an alternative to conventional ELISA systems and can be used for high-throughput screening in the BVD control programmes.

Assessment of the within- and between-laboratory repeatability of a commercially available Ostertagia ostertagi milk ELISA.

The objectives of this study were (1) to assess the within- and between-laboratory repeatability of a commercially available antibody-detection Ostertagia ostertagi ELISA (SVANOVIR(O). ostertagi-Ab, Svanova, Uppsala) and (2) to investigate if the assay could be further simplified by reading optical density at a single instead of double wavelength. A total of 80 bulk-tank milk samples were divided into aliquots and tested in duplicate per ELISA plate on 3 different days in 4 different laboratories (Bristol, Ghent, Hannover, Uppsala). The within- and between-laboratory repeatability of the ELISA was assessed by random effect models and the amount of variance attributable to each source of variation (duplicate within plate, day, laboratory and sample) was expressed as a proportion of the total between-sample variance. Overall, the within-laboratory repeatability was good in each laboratory with a proportion of total between-sample variance that could be attributed to assay variability of 5% in Ghent to 27% in Bristol. The between-laboratory repeatability was high: 15% of the total between-sample variance was attributable to the duplicate, 1% to the day, 2% to the laboratory and 82% to the sample. The range of deviations expected to include 95% of the observations when the same sample is tested in different laboratories was -0.23 to 0.23. The mean difference between the ODR values when the optical density was read at a single or double wavelength was -0.002 and the 95% confidence interval included zero. This study demonstrates that the SVANOVIR(O). ostertagi ELISA has a good repeatability and can be further simplified by reading optical density at a single instead of double wavelength. However, the observed variations in the within-laboratory repeatabilities suggest that regular ring testing is necessary when different laboratories cooperate in a same monitoring programme.

Detection of individual microbial pathogens by proximity ligation.

BACKGROUND: Nucleic acid amplification allows the detection of single infectious agents. Protein-based assays, although they provide information on ongoing infections, have substantially less detection sensitivity. METHODS: We used proximity ligation reactions to detect proteins on bacteria and virus particles via nucleic acid amplification. Antibodies recognizing viral or bacterial surface proteins were equipped with DNA strands that could be joined by ligation when several antibodies were bound in proximity to surface proteins of individual infectious agents. RESULTS: Detection sensitivities similar to those of nucleic acid-based detection reactions were achieved directly in infected samples for a parvovirus and an intracellular bacterium. CONCLUSIONS: This method enables detection of ligated DNA strands with good sensitivity by real-time PCR and could be of value for early diagnosis of infectious disease and in biodefense.

Prevalence of equine herpesvirus types 2 and 5 in horse populations by using type-specific PCR assays.

Equineherpesvirustypes 2 and 5 (EHV-2andEHV-5)have a rather unclearpathogenicity and distribution within the equid population. In order to gain more information on the prevalence of these two viruses, type-specific PCR assays were developed to detect viral DNA in nasal specimens and in peripheral blood leukocytes (PBLs) of adult horses and foals from various regions of Europe, i.e. Sweden, Hungary and the United Kingdom. In adult horses, the prevalence of EHV-2 in PBLs was up to 68% in Sweden and 71% in the United Kingdom. EHV-2 DNA was detected in the PBLs from all the foals tested in all countries and most (93%) of the nasal specimens also yielded positive results. The prevalence of EHV-5 DNA in the PBLs of foals in Hungary was 15 and 24% in adult horses in the United Kingdom. This observation was among the very few reports of the presence of EHV-5 in horses. In summary, the specific PCR assays revealed important data on the occurrence and distribution of EHV-2 and EHV-5 in large horse populations. The findings indicated that infection with EHV-5 occurred later than EHV-2 in foals. This study may contribute to a better understanding of the etiological role of these gammaherpesviruses in equine diseases.