Molecular Testing & Infectious Disease Immunology

Over the past decade, there has been an explosion in the use of molecular tests to diagnose and manage infectious diseases. The recent pandemic caused by the SARS-CoV-2 virus (COVID-19) has heightened and accelerated the importance of PCR technology.

Tuberculosis or Tb is a prime example of an infectious agent whose diagnosis in the acute stage, susceptibility testing, and management are all dependent on molecular diagnostics. The ability to accurately diagnose a range of respiratory pathogens rapidly within hours is now a common expectation by patients and clinicians for all laboratories regardless of cost and equipment availability.

Direct sequencing and microarray analysis hold great promise for directly detecting a wide variety of organisms from clinical specimens. The future is in whole-genome sequencing of viruses, bacterial pathogens, and cancer markers so that detection test kits and DNA amplification kits can be developed and adopted for use in diagnostic laboratories.

Closed molecular testing platforms requiring little user input such as GeneXpert and Abbott ID Now applications for TB, HIV viral loads, Hepatitis, Chlamydia, Gonorrhoea, Multi Drug-resistant pathogens, RSV and Coronavirus are the most common use of this methodology seen in the Pacific region.

Immunology and Serology departments utilise tests that are primarily based on the presence of antigens or the presence of immune response antibody production. Immune complexes develop that are measured by various immunoassay methods and integrated with automated analysers and computer systems.

Diagnostic applications used by the developing Pacific nations are based on rapid test kits with low specificity and sensitivity. The introduction of ELISA and immunoassay analysers will greatly improve the rate of detection and use of molecular platforms for confirmatory testing. This will enable the Pacific laboratories to perform testing in-country instead of having to refer these to overseas NZ or Australian laboratories.

Limitations of these complex assays are associated with the lack of specialised staff, who are not well versed in molecular diagnostic techniques. While the use of closed PCR technology is increasing throughout the Pacific, Real-Time PCR platforms are being introduced in Fiji, Marshall Islands, Nauru, Solomon Islands, Tonga, Palau and Tuvalu. Ongoing training of staff, reagent stock supply and troubleshooting support is required in these countries.

What PPTC Offers:

The PPTC can provide technical support to the Pacific Island laboratories in the following way:

• Identification of target pathogen/ diseases (viral or bacterial)
• Instrument selection, installation and reagent procurement guidance.
• Method/assay validation including a selection of primers and master mixes with the
• required internal quality control measures.
• Technical training in.
  • Local staff training in sample selection, processing, extraction, amplification, detection, and reporting.
  • Troubleshooting guidelines.
  • Guidance for method development and SOP write-up.
  • Establishing maintenance protocols.
  • Identifying an appropriate EQA programme for the laboratory to enrol in.