High resolution melting analysis of the 18S rRNA gene for the rapid diagnosis of bovine babesiosis

Assessing Different PCR Master Mixes for Ultrarapid DNA Amplification: Important Analytical Parameters

The basic principles of ultrafast plasmonic PCR have been promulgated in the scientific and technological literature for over a decade. Yet, its everyday diagnostic utility remains unvalidated in pre-clinical and clinical settings. Although the impressive speed of plasmonic PCR reaction is well-documented, implementing this process into a device form compatible with routine diagnostic tasks has been challenging. Here, we show that combining careful system engineering and process control with innovative and specific PCR biochemistry makes it possible to routinely achieve a sensitive and robust "10 min" PCR assay in a compact and lightweight system. The critical analytical parameters of PCR reactions are discussed in the current instrument setting.

A high-resolution melting approach for the simultaneous differentiation of five human babesiosis-causing Babesia species

BACKGROUND

Six species of apicomplexan parasites of the genus Babesia, namely B. microti, B. divergens, B. duncani, B. motasi, B. crassa-like and B. venatorum, are considered to be the primary causal agents of human babesiosis in endemic areas. These six species possess variable degrees of virulence for their primary hosts. Therefore, the accurate identification of these species is critical for the adoption of appropriate therapeutic strategies.

METHODS

We developed a real-time PCR-high-resolution melting (qPCR-HRM) approach targeting 18S ribosomal RNA gene of five Babesia spp. based on melting temperature (Tm) and genotype confidence percentage values. This approach was then evaluated using 429 blood samples collected from patients with a history of tick bites, 120 DNA samples mixed with plasmids and 80 laboratory-infected animal samples.

RESULTS

The sensitivity and specificity of the proposed qPCR-HRM method were 95% and 100%, respectively, and the detection limit was 1-100 copies of the plasmid with the cloned target gene. The detection level depended on the species of Babesia analyzed. The primers designed in this study ensured not only the high interspecific specificity of our proposed method but also a high versatility for different isolates from the same species worldwide. Additionally, the Tm obtained from the prepared plasmid standard is theoretically suitable for identifying isolates of all known sequences of the five Babesia species.

CONCLUSIONS

The developed detection method provides a useful tool for the epidemiological investigation of human babesiosis and pre-transfusion screening.

High-resolution melting analysis identifies reservoir hosts of zoonotic Leishmania parasites in Tunisia

BACKGROUND

Leishmaniasis is endemic in Tunisia and presents with different clinical forms, caused by the species Leishmania infantum, Leishmania major, and Leishmania tropica. The life cycle of Leishmania is complex and involves several phlebotomine sand fly vectors and mammalian reservoir hosts. The aim of this work is the development and evaluation of a high-resolution melting PCR (PCR-HRM) tool to detect and identify Leishmania parasites in wild and domestic hosts, constituting confirmed (dogs and Meriones rodents) or potential (hedgehogs) reservoirs in Tunisia.

METHODS

Using in vitro-cultured Leishmania isolates, PCR-HRM reactions were developed targeting the 7SL RNA and HSP70 genes. Animals were captured or sampled in El Kef Governorate, North West Tunisia. DNA was extracted from the liver, spleen, kidney, and heart from hedgehogs (Atelerix algirus) (n = 3) and rodents (Meriones shawi) (n = 7) and from whole blood of dogs (n = 12) that did not present any symptoms of canine leishmaniasis. In total, 52 DNA samples were processed by PCR-HRM using both pairs of primers.

RESULTS

The results showed melting curves enabling discrimination of the three Leishmania species present in Tunisia, and were further confirmed by Sanger sequencing. Application of PCR-HRM assays on reservoir host samples showed that overall among the examined samples, 45 were positive, while seven were negative, with no Leishmania infection. Meriones shawi were found infected with L. major, while dogs were infected with L. infantum. However, co-infections with L. major/L. infantum species were detected in four Meriones specimens and in all tested hedgehogs. In addition, multiple infections with the three Leishmania species were found in one hedgehog specimen. Sequence analyses of PCR-HRM products corroborated the Leishmania species found in analyzed samples.

CONCLUSIONS

The results of PCR-HRM assays applied to field specimens further support the possibility of hedgehogs as reservoir hosts of Leishmania. In addition, we showed their usefulness in the diagnosis of canine leishmaniasis, specifically in asymptomatic dogs, which will ensure a better evaluation of infection extent, thus improving elaboration of control programs. This PCR-HRM method is a robust and reliable tool for molecular detection and identification of Leishmania and can be easily implemented in epidemiological surveys in endemic regions.

Cross-priming amplification targeting the 18S rRNA gene for the rapid diagnosis of Babesia bovis infection

Babesia bovis is a known causative agent of bovine babesiosis and is widely distributed across China. Rapid detection and accurate identification of B. bovis is essential for follow-up management and epidemiological investigations. In this study, a cross-priming amplification combined with vertical flow (CPA-VF) assay was developed. The detection limit of the CPA-VF assay targeting the 18S rRNA gene was 320 fg per reaction at 61 °C for 60 min. No cross-reactions were observed with other piroplasms infective to cattle. Furthermore, 36 blood samples from experimentally-infected animals were accurately assessed using the CPA-VF assay. The performance of the CPA-VF assay was compared with the results of conventional PCR for 219 blood samples from the field. Our results demonstrate that the CPA-VF assay is a practical and effective diagnostic tool for bovine babesiosis caused by B. bovis infection.

Cross-sectional survey of cattle haemopathogens in Constantine, Northeast Algeria

This aim of the present study was to estimate the prevalence of haemopathogens in cattle in Beni Hamidene locality, district of Constantine (Νortheastern Algeria). Between June and October 2014, 169 bovines from 25 farms were included in this survey, 32 (18.9%) among them were suspected of piroplasmosis and/or anaplasmosis. Infection prevalences were estimated by microscopic examination of Giemsa‐stained blood smears and blood samples from all included cattle (n = 169). Animals were infected by Theileria annulata (65/169; 38.46%), Anaplasma marginale (22/169; 13%) and Babesia bovis (5/169; 3%). Two co‐infection patterns were found: Theileria annulata/Anaplasma marginale (7.69%) and Theileria annulata/Babesia bovis (1.18%). Only one farm had no cattle infected by any of the haemopathogens. There was a signification difference of T. annulata infection prevalence according to age category (p =.04). These results emphasised mainly the presence of bovine tropical theileriosis in northeastern, Beni Hamidene locality, province of Constantine, Algeria.

Knowledge, attitude and perception of bovine piroplasmosis by cattle owners in Constantine, North-East of Algeria, using participatory epidemiology

Cattle piroplasmoses are tick-borne diseases, spread worldwide that cause significant economic losses. A participatory epidemiological study was conducted individually or in focus groups with 73 cattle owners in Beni Hamidene locality (district of Constantine, Algeria). The aim of this study was to study cattle owners' knowledge, attitude and perception on cattle piroplasmosis. Proportional piling technique was used to determinate most common cattle diseases, and to evaluate economic impact of diseases according to the interwieved farmers. Theileriosis (49/73; 67.1%) and babesiosis (44/73; 60.3%) were considered the most important bovine diseases. No zoonotic disease was cited by the interviewed cattle owners. According to the majority of cattle owners, theileriosis and babesiosis are deadly diseases (87.3 and 78.1%, respectively). All cattle owners (73/73) cited fever as the most common symptom of tropical theileriosis. Some of them (14/73; 19.2%) do not make distinction between theileriosis and babesiosis. According to cattle owners (65/73; 89.0%), the use of acaricide is the most appropriate tick control method. This study provides information about knowledge on bovine piroplasmoses in Algeria. These information could be considered when performing control programmes by both animal decision-makers and field veterinarians.

Systematic Review of Ticks and Tick-Borne Pathogens of Small Ruminants in Pakistan

Ticks and tick-borne diseases (TTBDis) are a major constraint to the health and production of small ruminants in Pakistan. Despite being the subject of intermittent studies over the past few decades, comprehensive information on the epidemiology and control of TTBDis is lacking. Herein, we have systematically reviewed the current knowledge on TTBDis of small ruminants in Pakistan. Critical appraisal of the selected 71 articles published between 1947 to 2020 revealed that morphological examination had been the most widely used method for the identification of TTBDis in Pakistan. Tick fauna comprise at least 40 species, mainly belonging to Haemaphysalis, Hyalomma and Rhipicephalus. The prevalence of ticks is the highest in summer (June–September) and it is also higher in goats than sheep. Anaplasma, Babesia and Theileria spp. are the major tick-borne pathogens (TBPs), and their prevalence is usually higher in sheep than goats. Spatio-temporal distribution, genetic diversity and control of ticks and TBPs of small ruminants as well as the competence of tick vectors for various TBPs remain to be explored. Therefore, coordinated and focused investigations are required to fill knowledge gaps in these areas to maximise the health, production and welfare of small ruminants and minimise economic losses associated with TTBDis in Pakistan.