The videos aim to introduce laboratories to the process involved in conducting its Actiphage® Rapid and Actiphage® Core assays – the first highly sensitive tests for live mycobacteria that can be applied to both blood and milk samples.
Actiphage has gained worldwide interest to help tackle devastating mycobacterial diseases such as bovine TB and Johne’s disease.
The novel diagnostic method accurately identifies the presence of live mycobacteria such as M. bovis and M. paratuberculosis in as little as 6 hours, and since the test directly detects the bacteria rather than the immune response, it can be used to distinguish between infected and vaccinated animals.
The short videos show how to prepare a blood sample and a milk sample ready for Actiphage testing, and how to carry out the two different test formats: Actiphage Rapid and Actiphage Core.
Actiphage Rapid offers high sensitivity and is designed to indicate the presence or absence of mycobacteria in just 6 hours. To quantify the number of mycobacteria detected using this assay, it should be combined with a calibrated qPCR assay. PBD Biotech’s short ‘How to conduct the Actiphage Rapid assay’ video shows the ease and speed with which the 6-hour test can be conducted.
Actiphage Core is a 2-stage assay, providing mycobacteria detection and enumeration, followed by extraction of DNA and identification of the strain/s of mycobacteria present using standard PCR assays.
Dr Cath Rees, PBD Biotech’s Chief Scientific Officer, explains the difference between the two tests, “Actiphage Core requires two days, but identifies all viable mycobacteria present in a sample – not just those that you anticipate. For example, we once identified M. avium in blood samples that were suspected to contain M. paratuberculosis. Similarly we have detected M. paratuberculosis in milk samples that were being screened for the presence of M. bovis.
“The Actiphage Rapid method takes just 6 hours and is more sensitive than the Core assay, but you only detect the mycobacteria that correspond to the PCR primers used – and other species present would go undetected. However, the method can be multiplexed to identify multiple species in one sample.”
The additional advantage of Actiphage Core is that it is compatible with testing of large volume samples e.g. 50 ml milk samples, which typically contain PCR inhibitors, as the larger volumes used for the test allow these inhibitors to be diluted out through the sample processing.
Dr Cath Rees, who features in the series of PBD Biotech training videos, summarises how to decide which test to use. She says:
“Typically for detection of infection in blood we recommend an Actiphage Rapid test combined with either traditional or real-time PCR, and for presence/absence testing, the real-time PCR does not need to be a fully calibrated qPCR assay.
“For tests where you want to determine the number of specific mycobacterial cells present in a blood sample, we would recommend Actiphage Rapid used in combination with a fully calibrated qPCR assay.
“For testing samples where the nature of the mycobacteria to be detected is unknown, we would recommend Actiphage Core 2-day assay.
“For testing bulk milk, as part of a quality assurance programme, we would currently recommend the Actiphage Core 2-day assay to enumerate the number of mycobacteria detected and to allow the identification of specific pathogens. However, we are currently developing the protocols to test these types of samples using the Actiphage Rapid system.”
Both Actiphage assays offer the opportunity for early and accurate detection of live mycobacteria that will be of value to veterinary surgeons within the agricultural, domestic and exotic species sectors, helping to achieve improved containment and control of diseases.
It can also be used by food producers and processors as part of food safety and quality assurance programs. And provides a new tool for researchers who want to sensitively detect and enumerate mycobacteria, either in laboratory cultures or in samples from animal infections.
Both Actiphage Core and Actiphage Rapid are available to order.
