Pigeon Megrivirus (PiMeV)¶

Q: Is pigeon megrivirus harmful to racing pigeons?

The pathogenicity and virulence of PiMeV are not yet established. It is often detected in the droppings of pigeons with mild diarrhoea, but it has not been shown to cause serious disease directly, so it is best treated as a pathogen-monitoring finding.

Q: How was pigeon megrivirus discovered?

In 2013 Phan and colleagues first found and named PiMeV (strains MeV-B1/MeV-B2) in the droppings of feral pigeons in Hungary and Hong Kong; in 2024 Chinese researchers detected it in racing pigeons for the first time, confirming its presence in mainland Chinese pigeon flocks.

Q: How is pigeon megrivirus tested?

Real-time quantitative RT-PCR (RT-qPCR) is the method of choice, using specific primers designed against the conserved 3C gene. The limit of detection is 54 copies per microlitre and there is no cross-reaction with common pigeon pathogens such as Newcastle disease, avian influenza or circovirus.

Q: Are pigeon megrivirus and pigeon circovirus the same thing?

No. They belong to different virus families — PiMeV is in the family Picornaviridae, genus Megrivirus, while pigeon circovirus is in the family Circoviridae, genus Circovirus. Their testing targets and control approaches are entirely different.

Q: Does a positive PiMeV result require isolation?

PiMeV pathogenicity is unclear, so isolation on the scale used for a highly virulent disease is not necessary. Assess the result together with clinical signs and the results of other pathogen tests, and consult a veterinarian if needed.

Q: Should import quarantine include PiMeV testing?

As an emerging enteric virus, including it in the enteric pathogen screen at import gives a fuller picture of flock health, but it is not a mandatory test and can be decided according to the source of the birds and the perceived risk.

Key takeaway: Pigeon megrivirus (PiMeV) is a member of the family Picornaviridae, genus Megrivirus. It was first discovered and named in 2013 by Phan and colleagues in the droppings of feral pigeons in Hungary and Hong Kong. In 2024 Chinese researchers detected PiMeV for the first time in the droppings of racing pigeons with mild diarrhoea, confirming that the virus is present in mainland Chinese pigeon flocks. Its pathogenicity and virulence are not yet established, but as an emerging enteric virus it deserves a place in import quarantine and enteric pathogen screening for racing pigeons. Real-time quantitative RT-PCR (RT-qPCR) with primers designed against the conserved 3C gene detects PiMeV sensitively and specifically, with a limit of detection of 54.0 copies per microlitre.

Aetiology and taxonomy: locating PiMeV's "identity coordinates"¶

Pigeon megrivirus (PiMeV) belongs to the family Picornaviridae, genus Megrivirus. Under the classification of the International Committee on Taxonomy of Viruses (ICTV), the genus Megrivirus contains five virus species (types A-E), and PiMeV is assigned on genetic grounds to Megrivirus B.

The history of this classification goes back to 2013, when Phan and colleagues found Megrivirus in the droppings of feral pigeons in both Hungary and Hong Kong, named it pigeon megrivirus (PiMeV) and isolated strains MeV-B1 and MeV-B2. There was little research on it for several years afterwards, and it only returned to view recently as metagenomics and RT-qPCR became widely available.

Taxonomic level	Name
Family	Picornaviridae
Subfamily	Kodimesavirinae
Genus	Megrivirus
Species	Megrivirus B
Representative strains	MeV-B1, MeV-B2, PiMeV-CHN001

The family Picornaviridae comprises non-enveloped, positive-sense single-stranded RNA viruses. The genome carries a VPg protein at the 5' end that acts as a primer for RNA replication, and the virion is icosahedral — the molecular basis for its relative stability in the environment and its ability to spread by the faecal-oral route.

Genome and 3C protein: the molecular basis of the detection target¶

The PiMeV genome follows the general picornavirus layout: VPg + 5'UTR[IRES] - structural proteins (1A-1B-1C-1D) - non-structural proteins (2A-2B-2C-3A-3B-3C-3D). The non-structural protein genes 1B, 1C, 1D, 2C, 3C and 3D are highly conserved between strains, making them ideal regions for designing molecular detection targets.

Chinese researchers cloned and sequenced the 3C gene of strain PiMeV-CHN001 with the following results:

Measurement	Value	Significance
Full length of the 3C gene	591 bp	Conserved target region, suitable for designing specific primers
Encoded amino acids	197 aa	Encodes the 3C protease (3CPro)
Nucleotide similarity to strain MeV-B1	89.5%	Same Megrivirus B evolutionary branch
Nucleotide similarity to strain MeV-B2	92.0%	Closely related genetically

The 3C protease (3CPro) expressed from the 3C protein uses a hydrogen-bond network to arrange the catalytic amino acids Cys, His and Asp/Glu into a catalytic triad, and takes part in processing the picornavirus polyprotein. Recent work shows that the 3C protein also participates in cleaving viral precursor proteins, promotes viral replication, regulates apoptosis and helps evade the immune response. It is the key molecule for understanding PiMeV biology and the basis for the specificity of RT-qPCR detection.

Epidemiology and detection findings: from feral pigeons to racing pigeons¶

Understanding of the PiMeV host range has widened step by step:

2013: Phan and colleagues first found it in the droppings of feral pigeons in Hungary and Hong Kong and named it PiMeV (strains MeV-B1 and MeV-B2);
2024: Chinese researchers amplified the target PiMeV fragment (strain PiMeV-CHN001) from the droppings of racing pigeons with mild diarrhoea, confirming for the first time that PiMeV is present in mainland Chinese racing pigeon flocks and broadening its known host range;
Of 42 racing pigeon faecal samples tested, 2 were positive, a positive rate of about 4.76%.

It must be emphasised that although Megrivirus has repeatedly been identified in birds with conditions such as turkey viral hepatitis, whether it causes disease in its host, and how virulent it is, remain undetermined. Control strategy for PiMeV should therefore centre on monitoring and screening rather than treating it as a highly virulent disease.

Real-time quantitative RT-PCR detection: method and performance¶

There is no commercial routine test for PiMeV, and real-time quantitative RT-PCR (RT-qPCR) is currently the most sensitive and specific method. The performance of the established PiMeV RT-qPCR assay is as follows:

Performance parameter	Value	Interpretation
Standard curve correlation coefficient (R²)	1.00	Excellent linearity
Amplification efficiency	99.4%	Close to theoretical optimum
Limit of detection	54.0 copies per microlitre	High sensitivity
Specific Tm value	(81.69 ± 0.22) °C	Stable specific peak
Intra/inter-assay coefficient of variation	< 1.5%	Good reproducibility

Specificity verification: the assay produces a specific amplification signal only for PiMeV, with no cross-reaction against pigeon avian influenza virus (AIV), pigeon avian paramyxovirus 1 (PPMV-1), pigeon torque teno virus (PTTV), pigeon adenovirus (PiAd) or pigeon circovirus (PiCV) — which guarantees accurate identification even in mixed-infection settings.

Practical workflow (using faeces or cloacal swabs as an example):

Sampling: collect fresh faeces or a cloacal swab, place it in a sterile sample tube, store cold and submit as soon as possible;
Nucleic acid extraction: extract total RNA with a viral RNA extraction kit;
Reverse transcription: obtain cDNA by reverse transcription;
RT-qPCR amplification: amplify the conserved region of the 3C gene with the primer set and probe, and read the Ct value and Tm value;
Interpretation: call positive or negative from the standard curve together with the specific Tm value.

Warning: PiMeV pathogenicity is unclear, so a positive result should be assessed from a pathogen-monitoring standpoint together with clinical signs. Do not over-react.

Key points¶

PiMeV is a member of the family Picornaviridae, genus Megrivirus (Megrivirus B), first found and named in feral pigeons in 2013.
In 2024 it was detected for the first time in the droppings of racing pigeons in China (positive rate about 4.76%), confirming its presence in mainland Chinese pigeon flocks.
The 3C gene (591 bp, encoding 197 aa) is highly conserved and is the specific target for RT-qPCR detection.
RT-qPCR performance is excellent: correlation coefficient 1.00, amplification efficiency 99.4%, limit of detection 54 copies per microlitre, no cross-reaction.
PiMeV pathogenicity is not yet settled, so control should centre on monitoring and screening; consult your veterinarian or the Sanshi Bio technical team for specifics.

Quick reference: entities¶

Chinese name	English name / abbreviation	Notes
鸽微RNA病毒	Pigeon megrivirus / PiMeV	Member of the family Picornaviridae, genus Megrivirus
小核糖核酸病毒科	Picornaviridae	Family of non-enveloped positive-sense single-stranded RNA viruses
微RNA病毒属	Megrivirus	Contains types A-E; PiMeV belongs to type B
3C 蛋白酶	3C protease / 3CPro	Involved in polyprotein processing; the detection target protein
实时荧光定量 RT-PCR	Real-time RT-qPCR	Method of choice for PiMeV detection
最低检测限	Limit of Detection / LoD	54.0 copies per microlitre

FAQ¶

Is pigeon megrivirus harmful to racing pigeons?¶