Testing for Human Metapneumovirus

Medical News: Human metapneumovirus (HMPV) is a significant viral cause of acute respiratory tract infections (ARI). Affecting both children and immunocompromised individuals, this virus often leads to severe complications such as bronchiolitis and pneumonia. Researchers from Hallym University College of Medicine’s Kangnam Sacred Heart Hospital and Yonsei University’s Severance Hospital in South Korea have extensively studied advancements in detecting HMPV, aiming to improve diagnostic accuracy and patient outcomes.


Testing for Human Metapneumovirus

First identified in the Netherlands through genetic analysis of nasopharyngeal samples from children with respiratory symptoms, HMPV has since been linked to high morbidity rates globally. Its genome, composed of negative-sense, single-stranded RNA, codes for proteins like fusion glycoproteins and nucleoproteins, which are critical for virus replication and infection. Advances in diagnostic methods have significantly evolved over the years, transitioning from traditional culture methods to cutting-edge molecular techniques. (Thailand Medical News would like to add that since 2020 till now, there has been no further attempts by any biotech companies to further improve the efficiency of HMPV testing nor the development of newer and innovative faster and cheaper diagnostic platforms for HMPV).
 
Traditional Detection Methods
In earlier years, viral culture was considered the gold standard for diagnosing HMPV. Samples were inoculated into permissive cell lines, such as LLC-MK2, and monitored for cytopathic effects (CPE) over days. While effective, these methods were time-consuming and less sensitive compared to modern molecular techniques. This article highlights how advancements in molecular biology have revolutionized the detection landscape, reducing both turnaround times and labor intensity.
 
Shell vial culture emerged as a modified and faster version of the traditional approach. By utilizing centrifugation and antibody-based detection, it allowed for quicker identification of viral antigens. Fluorescent immunoassays (FIAs), including direct fluorescent antibody tests, were also widely adopted, providing more accessible and rapid results. Despite these improvements, the sensitivity and specificity of these methods fell short of those offered by polymerase chain reaction (PCR)-based techniques.
 
The Rise of Polymerase Chain Reaction Methods
The introduction of reverse transcriptase-polymerase chain reaction (RT-PCR) marked a pivotal shift in HMPV diagnostics. RT-PCR allows for the detection of viral RNA through the reverse transcription of RNA into complementary DNA (cDNA), followed by amplification using PCR. This method offers unmatched sensitivity and specificity.
 
Real-Time RT-PCR
Real-time RT-PCR emerged as a reliable method for detecting HMPV, enabling simultaneous nucleic acid amplification and detection in a single step. Laboratories worldwide utilize automated platforms like Roche’s MagNaPure Compact system and bioMérieux’s NucliSENS easyMAG for RNA extraction and purification. These platforms ensure high-quality and reproducible results. Among the targeted genes, the N gene stands out for its high conse rvation across HMPV genotypes, making it a preferred choice for reliable detection.
 
Multiplex RT-PCR
Multiplex RT-PCR further advanced the field by allowing the detection of multiple viral pathogens in a single assay. This technique uses multiple primer sets within one PCR reaction, enabling simultaneous identification of HMPV alongside other respiratory viruses. The FilmArray system by BioFire Diagnostics is a prime example, integrating nucleic acid extraction, PCR, and data analysis in a compact system. Its user-friendly design and short runtime have made it a favorite among clinical laboratories.
 
Microarray and Emerging Technologies
Beyond PCR, microarray technologies have emerged as powerful tools for high-throughput viral detection. These systems utilize microscopic DNA spots bound to solid surfaces to analyze amplified PCR products. Platforms like Genomica’s CLART PneumoVir and the BioMark system offer advanced capabilities for detecting multiple respiratory viruses, including HMPV.
 
Suspension microarrays, such as the Luminex xTAG RVP fast assay, further enhance flexibility and reduce costs. These systems use liquid-phase bead-conjugated microarrays to analyze viral RNA, providing results with high sensitivity and specificity. While these methods offer comprehensive diagnostic capabilities, they are often complex and require specialized expertise.
 
Comparative Advantages of Modern Techniques
Studies have shown a significant shift in diagnostic preferences over the years. From 2001 to 2010, traditional methods like viral culture and FIAs were employed in 21.4% of studies. However, this figure dropped to 15.2% from 2011 to 2019, coinciding with a rise in PCR-based techniques. Real-time RT-PCR and multiplex PCR became the dominant methods due to their higher diagnostic performance, shorter processing times, and reduced risk of contamination.
 
For instance, the FilmArray system demonstrated superior sensitivity compared to traditional methods, detecting up to 30% more respiratory viruses. Similarly, the Luminex system showed a positivity rate of 47.5%, outperforming traditional FIAs and conventional RT-PCR. These advancements have drastically improved the speed and accuracy of HMPV diagnosis, directly benefiting patient care.
 
Challenges and Future Directions
Despite these advancements, challenges remain. The high cost of molecular diagnostic tools and the need for specialized training can limit accessibility in resource-constrained settings. Additionally, mutations in the HMPV genome can affect the accuracy of PCR-based assays, necessitating continuous updates to primer and probe designs.
 
Looking ahead, the integration of nanotechnology and next-generation sequencing (NGS) holds promise for further enhancing HMPV diagnostics. NGS allows for comprehensive genomic analysis, enabling the identification of emerging viral strains and facilitating personalized therapeutic approaches. However, these technologies require rigorous analytical and clinical validation before widespread implementation.
 
Cost Of HMPV test at Private labs and Hospitals in Thailand, United Kingdom and United States.
Thailand Medical News found that cost of having a test for HMPV done at private labs or hospitals in countries like Thailand, United Kingdom and United States, starts at US$130 and goes up to US$620! Results can be known within 20 minutes to 3 hours! This puts it out of reach for most common people!

Most public hospitals in the UK under the NHS typically do not conduct any HMPV tests unless in extraordinary cases!
 
Conclusion
The evolution of HMPV diagnostics underscores the importance of innovation in addressing public health challenges. Traditional methods, while foundational, have largely been replaced by molecular techniques that offer superior sensitivity, specificity, and efficiency. Tools like real-time RT-PCR, multiplex PCR, and microarray platforms have revolutionized the detection landscape, enabling timely and accurate diagnoses.
 
As we continue to advance, the focus must remain on improving accessibility and affordability of these cutting-edge technologies. The integration of emerging tools like NGS and nanotechnology will pave the way for even more precise and personalized approaches to managing HMPV infections.
 
The study findings were published in the peer-reviewed journal: Annals of Translational Medicine.
https://atm.amegroups.org/article/view/34042/html
 
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Read Also:
https://www.thailandmedical.news/news/how-human-metapneumovirus-gains-entry-into-cells
 
https://www.thailandmedical.news/news/hmpv-infections-and-hospitalizations-continue-to-rise-in-china-while-researchers-are-focusing-on-the-new-lineages-from-subtype-a2
 
https://www.thailandmedical.news/articles/hmpv-human-metapneumovirus