The causes of false-positives encountered during the screening of old-world primates for antibodies to human and simian retroviruses by ELISA

Assessment of Plasma Tylosin Concentrations: A Comparative Study of Immunoassay, Microbiological Assay, and Liquid Chromatography/Mass Spectrometry

Employing affordable and uncomplicated sample preparation techniques to recommend the most efficient antibacterial therapy could help reduce antibiotic-resistant bacteria. This study evaluated the suitability of immunoassays and microbiological assays as alternatives for liquid chromatography/mass spectrometry (LC/MS) in determining plasma tylosin concentrations after intramuscular administration at a dose of 20 mg/kg to both healthy and diseased pigs in clinical veterinary practice. The diseased pigs were confirmed using the target genes Actinobacillus pleuropneumoniae (apxIVA) and Pasteurella multocida (kmt1). The methods showed good linearity, precision, and accuracy. In both healthy and diseased pigs, a significant correlation was observed between LC/MS and the microbiological assay (Pearson correlation coefficient: 0.930, p < 0.001 vs. Pearson correlation coefficient: 0.950, p < 0.001) and between LC/MS and the enzyme-linked immunosorbent assay (ELISA) (Pearson correlation coefficient: 0.933; p < 0.001 vs. Pearson correlation coefficient: 0.976, p < 0.001). A strong correlation was observed between the microbiological assay and the ELISA in both healthy and diseased pigs (Pearson correlation coefficient: 0.911; p < 0.001 vs. Pearson correlation coefficient: 0.908, p < 0.001). A Bland-Altman analysis revealed good agreement between the methods, i.e., 95% of the differences were within the limits of agreement. Therefore, the microbiological assay and the ELISA, which demonstrated sufficient precision and accuracy, can be viable alternatives to LC/MS when it is unavailable.

Development, application, and quality control of serology assays used for diagnostic monitoring of laboratory nonhuman primates

The careful development, validation, and implementation of serodiagnostic assays can provide reliable results that make them a valuable tool in microbial quality control for nonhuman primates. This article includes identification and description of the components of assay development, including formulas for calculating the number of positive serum samples needed for assay validation and methods for calculating their diagnostic sensitivity and specificity. To ensure that assays are performing within predetermined specifications, there must be a quality control system that includes appropriate system and sample suitability controls as well as mechanisms to track assay performance over time. The section on quality assurance includes definitions of precision and accuracy in assay performance, and how to interpret these two factors using the Levey-Jennings chart, Westgard's rules, and other monitoring methods. Because all serologic assays are prone to false positive and false negative results, it is essential to interpret all diagnostic test results using both the expected prevalence of disease in the population and the population-specific assay performance characteristics that are determined during assay validation. The discussion on interpreting diagnostic test results also includes guidelines for calculating the positive and negative predictive values of an assay and for interpreting results based on the disease prevalence of the test population. A glossary provides definitions of commonly used terms.

Simultaneous detection of simian retrovirus type D serotypes 1, 2, and 3 by polymerase chain reaction

Asymptomatic infection of macaques with macaques with simian retroviruses type D (SRV/D), the etiologic agents of one form of retrovirus-induced simian immunodeficiency disease, can confound experiments with the simian immunodeficiency virus (SIV), which also induces immunodeficiency disease in macaques. The SIV/macaque model is the preferred nonhuman primate model for AIDS-related research. Serological screening for SRV/D alone is insufficient because not all infected animals seroconvert, and virus isolation by cocultivation may require 4 to 6 weeks. We have established a DNA polymerase chain reaction (PCR) assay. One set of nested primers allows detection of SRV/D serotypes 1, 2, and 3 and distinguishes SRV-2 from the other two serotypes. The PCR assay is sensitive; a single proviral copy of SRV/D could be detected in 150,000 to 210,000 macaque peripheral blood mononuclear cells (PBMCs). When applied to a panel of virus isolation-positive macaque samples, the PCR assay was positive in 100% of the tests. No false-positive results were seen when known specific-pathogen-free (SPF) macaques were examined. We propose that macaques be screened with a combination of SRV/D serology and this DNA PCR assay prior to enrollment in experiments with SIV.

ELISA for detection of antibodies to a type D retrovirus, SRV-W

An ELISA was developed to detect antibodies to a Type D retrovirus, SRV-W. The interpretation of the ELISA results were based on: 1) Comparisons of known antibody positive (to a closely related type D retrovirus) and negative serum samples, 2) the ability of ELISA reactivity to be absorbed with a Type D virus but not a mock virus preparation, and 3) analysis by a Western Blot assay as an alterative way to identify antibody to the Type D retrovirus.

Dot immunobinding assay compared with enzyme-linked immunosorbent assay for rapid and specific detection of retrovirus antibody induced by human or simian acquired immunodeficiency syndrome

A rapid, specific, and sensitive modification of the dot immunobinding assay was compared with the standard enzyme immunoassay as a screening procedure for the detection of antibody in human or simian acquired immunodeficiency syndrome. Comparative testing with the available enzyme immunoassay procedures, either in commercial kit form or as provided by diagnostic laboratories, indicated excellent correlation. Ease of operation and cost are key features of the dot immunobinding assay procedure.

Effects of trapping on the vervet (Cercopithecus aethiops sabaeus) population in Barbados

The effects of a 7-year trapping program on a population of vervets, Cercopithecus aethiops sabaeus, in Barbados is described. The pretrapping population was estimated at between 6,000 and 12,000 monkeys. The number trapped annually has increased from less than 200 in 1980 to almost 1,000 in 1986. Despite this, annual catch per trapping effort indicates that population abundance has remained relatively constant. However, the proportion of juveniles to adults in the population has increased markedly, largely because of an increase in the proportion of juvenile females. The data, therefore, suggest that the number of adults in the feral population has been decreasing, while that of juveniles has been increasing. The observation that adults are more vulnerable to trapping than juveniles and the possibility that juvenile survivorship has increased since trapping began may explain these trends. The change in age structure of the population toward juveniles is one explanation for the claimed increase in crop damage in Barbados at constant population size.