Tests Suggested for Pirola Variant - A Diagnostic Perspective

Introduction

Ever since the emergence of the SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) and the eventual outbreak of the COVID-19 (Coronavirus disease) pandemic, the United States Centers for Disease Control and Prevention (CDC) has been constantly tracking the behavior of the coronavirus.

Generally, viruses tend to change their genetic composition (undergo mutation) and evolve into new viral subtypes. The newly emerged viral strains are widely referred to as variants, and they pose challenges in diagnosing and treating the illnesses caused by them.

Recently, a new variant of coronavirus, BA.2.86, has emerged, leading to global concern. The WHO (Wealth Health Organization) and CDC are vigilantly monitoring the sequential approach to diagnose this variant at an early phase and prevent its community spread, thereby controlling widespread outbreaks.

Why Is the Pirola Variant Unique?

A new coronavirus variant has emerged recently and has been designated the BA.2.86 variant. This novel viral subtype is informally nicknamed the Pirola variant.

Some known facts about this unique variant are as follows:

• The Pirola variant, BA.2.86, is a subvariant that emerged from the Omicron lineage.

• The CDC isolated this new variant first in Denmark in July 2023, followed by samples from Israel and the United Kingdom (UK). The Pirola variant has started to appear and is being detected in the United States (U.S.) from August 2023.

• The Pirola variant is unique compared to other sub-variants because this BA.2.86 subvariant has numerous mutations associated with spike proteins (an essential feature that helps in viral attachment).

• These mutations in Pirola make it notable as they result in several genetic diversifications from previously existing SARS-CoV-2 versions.

• BA.2.86 variants are predominantly detected in wastewater samples through the National Wastewater Surveillance System (NWSS) in the U.S., indicating a potential public health risk of spreading through wastewater.

• Since the virus has been detected across various continents, the Pirola variant has considerable transmissibility. However, the disease severity is not severe and does not show increased infectivity.

• However, prolonged infections in immunocompromised individuals would lead to related complications.

What Is the Recent Risk Assessment Scenario of the Pirola Variant?

Scientific studies and clinical research are ongoing to analyze the massive mutational shift in the Pirola variant. With the available data, the CDC has assessed potential risk factors that may or may not progress to major public health concerns.

The detailed risk assessment report from the CDC on the Pirola variant is summarized below:

• According to the mutation profile of BA.2.86, its impact on molecular diagnosis and antigen-based assays is anticipated to be low.

• However, the regulatory body has guaranteed the existing COVID-19 diagnostic tests and therapeutic medications are found to be working and effective with the newly emerged Pirola variant.

• The efficacy of existing vaccines is also being assessed against this viral strain. Also, vaccines are updated to reduce the severity of the illness and decrease hospitalization rates.

What Are the Tests Suggested for Detecting the Pirola Variant?

Numerous diagnostic tests have been developed in recent months to enhance quick and accurate detection of the COVID-19 virus.

Some of the suggested tests for detecting the Pirola variant are as follows:

• Molecular Tests for BA.2.86 Detection - This is also called the nucleic acid amplification test (NAAT). It is based on the PCR (polymerase chain reaction) principle, where the genetic material (RNA in the coronavirus case) is amplified and detected using appropriate techniques. It is considered the gold standard diagnosis because even traces of viral RNA can be detected accurately.

• This test works for detecting the Pirola variant since the targeted genetic sequence is viral RNA (core element). Mutations are seen primarily in spike protein sequences.

• However, due to unpredictable mutagenicity, samples with low viral load would show false negative results.

• The samples best preferred for this test is nasal or throat swab and saliva. It is collected by a trained healthcare provider and is sealed in a leak-proof container.

• The test results are obtained within 48 hours (maximum seven days) from the time of sample collection.

• Antigen Tests for BA.2.86 Detection - Antigen tests are more straightforward as they do not need sophisticated techniques like PCR. These are reagent-based tests where synthesized antibodies (through recombinant technology) are used to detect viral antigens.

• This test would show low sensitivity if the viral load is minimal in the samples. However, they are effective as screening tests.

• The existing antigen tests effectively detect all viruses from Omicron lineages; hence, the presence of Pirola is also effectively detected using antigen-based tests.

What Are the Newer Developments in Detecting the Pirola Variant?

Regulatory bodies like the FDA (Food and Drug Administration) are continuously monitoring the development of new diagnostic tools to help detect coronavirus variants early and accurately.

Some of the recently used techniques are as follows:

• Rapid Molecular Detection Tests - They are point-of-care testing kits that give results within 15 minutes and are more accurate than antigen-based diagnostic tests.

• Home Tests - These are based on the antigen-antibody principle and are useful in screening for the presence of the Pirola variant in suspected individuals.

What Are the Factors Influencing the Detection of the Pirola Variant?

Detecting the Pirola variant remains challenging as several factors contribute to accurate sensitivity and specificity.

The following factors should be considered while testing for the Pirola variant.

• Infectivity Period - The virus is best detected during the initial phases of infectivity (within 14 days). The antigenic response declines once antibodies are produced due to the neutralizing effect.

• Extreme Mutagenicity - The Pirola variant shows massive changes in genetic sequences, which would skip the amplification process in PCR showing false negative results.

• Previous Vaccination - Recent vaccination or booster dosing could affect the diagnosis of the Pirola variant.

• Recommendations - The CDC recommends a battery of diagnostic tests scheduled based on scientific data for detecting emerging variants. This helps maximize the diagnosis spectrum so that the chances of detecting the new variant remain higher.

Conclusion

New variants of coronavirus are continuously emerging, and their potency to cause illness vividly varies from one subtype to another. Global organizations like the CDC conduct continuous genomic surveillance to detect emerging new strains. The Pirola variant is most recently picked by the CDC’s Traveler-based Genomic Surveillance. It is reported that existing diagnostic tests are working on this new variant, enabling early detection of the Pirola variant.