A Novel PCR Assay for Detecting Brucella abortus and Brucella melitensis

Development of a simplified and cost-effective sample preparation method for genotyping of human papillomavirus by next-generation sequencing

High-risk human papillomavirus (HPV) infection is the most common cause of cervical cancer, but low-risk HPV strains can sometimes also be involved. Although HPV genotyping techniques used in clinical diagnosis cannot detect low-risk HPV, next-generation sequencing (NGS) can detect both types. However, DNA library preparation is complicated and expensive. The aim of this study was to develop a simplified, cost-effective sample preparation procedure for HPV genotyping based on next-generation sequencing (NGS). After DNA extraction, a first round of PCR was performed using modified MY09/11 primers specific for the L1 region of the HPV genome, followed by a second round of PCR to add the indexes and adaptors. Then, the DNA libraries were purified and quantified, and high-throughput sequencing was performed using an Illumina MiSeq platform. The sequencing reads were compared with reference sequences for HPV genotyping. The limit of detection for HPV amplification was 100 copies/µl. Analysis of the correlation of pathological cytology with the HPV genotype in individual clinical samples showed that HPV66 was the most common genotype found in the normal stage, whereas HPV16 was the main genotype found in low-grade squamous intraepithelial lesions, high-grade squamous intraepithelial lesions, and cervical cancer. This NGS method can detect and identify several HPV genotypes with 92% accuracy and 100% reproducibility, and it shows potential as a simplified and cost-effective technique for large-scale HPV genotyping in clinical samples.

Survey of Zoonotic Bacterial Pathogens in Native Foxes in Central Chile: First Record of Brucella canis Exposure

Simple Summary

Wild canids play a crucial role in the environment, being an ecological agent of flora dispersal, top predators, and environmental sentinels for zoonotic emerging pathogens, such as Brucella spp. and pathogenic Leptospira. In Chile, three species of non-domestic native canids are present, and due to the growing concern about their interaction with humans and domestic animals, it is of utmost relevance to determine the role of these animals in the epidemiology of brucellosis and leptospirosis. This study aimed to detect the exposure to B. abortus, B. canis, and pathogenic Leptospira by serologic, bacteriologic, and molecular techniques in native foxes from rehabilitation and exhibition centers in Central Chile. Forty-six blood samples were obtained from culpeo and grey foxes, detecting exposure to B. canis and L. Javanica in 10.9% and 7.7%, respectively. Exposure was not registered by culture and qPCR in any of the sampled animals. Our results show for the first time in Chile exposure to B. canis in native foxes, highlighting the need to establish integrated surveillance programs to better evaluate the role of wild animals in the epidemiology of emerging zoonotic pathogens that may affect One Health.

Abstract

Brucella abortus, B. canis, and pathogenic Leptospira are zoonotic pathogens that infect humans, as well as domestic and wild animals. In wild canids, they may affect their fertility and reproduction, threatening their conservation. Wild canids play a crucial role in the environment as meso- and top-predators and environmental sentinels for zoonotic pathogens. In Chile, three species of wild canids are present, and due to changes in land use and environmental dynamics, it is of utmost relevance to determine the role of these species in the epidemiology of brucellosis and leptospirosis. This study aimed to detect the exposure to B. abortus, B. canis, and pathogenic Leptospira by serologic, bacteriologic, and molecular techniques in native foxes from rehabilitation and exhibition centers in Central Chile. Forty-six blood samples were obtained from Lycalopex culpaeus and L. griseus, detecting 10.9% of seropositivity to B. canis and 7.7% to L. Javanica. No seropositivity was seen for B. abortus. Exposure was not registered by culture and qPCR in any of the sampled animals. Our findings are the first register of exposure to any Brucella species in wild canids in Chile and highlight the need to establish surveillance programs of these emerging pathogens.

Bovine brucellosis - a comprehensive review

Brucellosis is a zoonotic disease of great animal welfare and economic implications worldwide known since ancient times. The emergence of brucellosis in new areas as well as transmission of brucellosis from wild and domestic animals is of great significance in terms of new epidemiological dimensions. Brucellosis poses a major public health threat by the consumption of non-pasteurized milk and milk products produced by unhygienic dairy farms in endemic areas. Regular and meticulous surveillance is essentially required to determine the true picture of brucellosis especially in areas with continuous high prevalence. Additionally, international migration of humans, animals and trade of animal products has created a challenge for disease spread and diagnosis in non-endemic areas. Isolation and identification remain the gold standard test, which requires expertise. The advancement in diagnostic strategies coupled with screening of newly introduced animals is warranted to control the disease. Of note, the diagnostic value of miRNAs for appropriate detection of B. abortus infection has been shown. The most widely used vaccine strains to protect against Brucella infection and related abortions in cattle are strain 19 and RB51. Moreover, it is very important to note that no vaccine, which is highly protective, safe and effective is available either for bovines or human beings. Research results encourage the use of bacteriophage lysates in treatment of bovine brucellosis. One Health approach can aid in control of this disease, both in animals and man.

Development and validation of immunoassay for whole cell detection of Brucella abortus and Brucella melitensis

Brucella is alpha-2 Proteobacteria mainly responsible for multi-factorial bacterial zoonotic disease brucellosis with low concentration (10–100 CFU) required to establish the infection. In this study, we developed sandwich ELISA with detection range of 10² to 10⁸ cells mL⁻¹ and limit of detection at 10³ cells mL⁻¹ by employing polyclonal rabbit IgG (capture antibody, 10 µg mL⁻¹) and mice IgG (detection antibody, 50 µg mL⁻¹) antibody for its detection. Surface Plasmon Resonance evaluated the interaction of detection antibody with whole cell spiked serum samples at LOD of 10² cells mL⁻¹ along with non co-operative interaction of protein albumin. Further, kinetic evaluation study using detection antibody against cell envelope antigen was performed whereby, Equilibrium Dissociation Constant (K_D) and Maximum Binding Capacity (B_max) were found to be 16.48 pM and 81.67 m° for Brucella abortus S99 and 0.42 pM and 54.50 m° for Brucella melitensis 16 M, respectively. During interference study, sandwich ELISA assay cross-reacted with either of the polyclonal antibody of above Brucella species. Upon validation, no cross-reactivity observed with bacteria-closely related to Brucella. In conclusion, developed semi-quantitative sandwich immunoassay is sensitively rapid in whole cell detection of Brucella and will be useful in development of detection assays from environmental and clinical matrices.

Comparison of PCR-RFLP and PFGE for determining the clonality of Brucella isolates from human and livestock specimens

Brucellosis is an important zoonotic disease caused by different species of genus Brucella that are pathogenic for humans and a variety of animals. Accurate detection of Brucella spp. infection is important for control of disease. The aim of this study was to comparison of molecular genotyping of Brucella strains by Pulsed-field gel electrophoresis (PFGE) and polymerase chain reaction -Restriction Fragment Length Polymorphism (PCR-RFLP) techniques. Twenty- seven Brucella spp. were isolated from human and animal samples. The isolates identified by conventional microbiological methods and confirmed using PCR for amplification of omp2a gene. Molecular typing of Brucella strains carried out by PCR-RFLP after PstI and PFGE of chromosomal DNA after XbaI enzyme digestion. The omp2a gene PCR Products with different patterns of PCR-RFLP were sequenced. The omp2a gene amplification of all human and animal Brucella isolates were positive for 1100 bp fragment. By PCR-RFLP analysis two genotypes/patterns for human isolates and four genotypes for animal isolates were obtained. In PFGE analysis totally, 7 common clones/clusters and 3 single clones were obtained. The results of this study showed the PFGE method is the more reliable and useful assay for molecular typing of Brucella strains and is more preferred to PCR-RFLP in determination of genetic similarity among human and animal Brucella isolates. The presented data showed PCR-RFLP analysis was not able to differentiate between B. melitensis biovars and vaccine strain.

Designing an immunosensor for detection of Brucella abortus based on coloured silica nanoparticles

Brucellosis has always been a threat to the health and economics of societies. We report a new colorimetric immunoassay based on colored silica nanoparticles for detection of Brucella abortus. An immunosensor was designed based on blue-SiNPs and paramagnetic nanoparticles (PMNPs). The synthesized immunosensor was conjugated with a polyclonal antibody against B. abortus, which was activated by 1-Ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) and N-hydroxysuccinimide (NHS) to form detection and capture probes, respectively. After adding the conjugates to the bacterial suspension, sandwich structure of PMNPs B. abortus-blue-SiNPs was formed and then separated by a magnet. The blue dye was released from the silica structure and its absorbance was measured at 670 nm with a spectrophotometer. Under optimal conditions, results showed a wide dynamic range from 1.5 × 10³ to 1.5 × 10⁸ cfu mL^-1 with a detection limit of 450 cfu mL^-1. The specificity of the sensor was confirmed in comparison with 5 other bacteria. Also, during the 120-days period, the complex was stable. The results suggested that it can be used in real samples (R² = .9865). This designed colorimetric immunoassay strategy can be used as an alternative, user-friendly and on-site tool for the rapid detection of Brucella spp. compared to other common methods with high sensitivity and specificity in a short time.