In the Mediterranean province of Burdur, in southern Türkiye, veterinary researchers working across 2021 and 2022 examined blood from 444 unvaccinated cattle, all showing signs of illness, and asked a quiet but consequential question: which strains of a long-known livestock virus are moving through the herds. The answer, that about one animal in five carried a pestivirus and that the isolates belonged to two lineages, subgenotypes 1b and 1l, places a local outbreak within a larger pattern of diversity and endurance in the virus family that has troubled cattle farming for decades. It is a remin
Study Confirms BVDV-1 Subgenotypes 1b and 1l Circulating in Cattle Across Burdur, Türkiye
Calves that shed the virus for life, a standing reservoir inside the herd
Mark
Eighteen point seven percent sounds high. What does it actually tell us?
Mimi
That nearly one in five of these sick, unvaccinated cattle in Burdur carried a pestivirus. The highest rates were in animals with reproductive problems, 22.9 percent, and growth retardation, 22.7 percent.
Luke
But these were animals already showing compatible signs. That isn't the prevalence across all cattle in Burdur, so I wouldn't read it as a herd-wide rate.
Mark
Why do persistently infected calves matter so much?
Mimi
They are infected in the womb, early in gestation, and shed virus their whole lives. They keep the virus circulating.
Luke
The study points to removing them, but it doesn't say how many of these 83 were persistently infected. A single test can't distinguish that.
Mark
And the subgenotypes?
Mimi
Of five isolates sequenced, two were 1b, the most common type worldwide, and three were 1l, an endemic lineage in Türkiye.
Luke
Five isolates is a very small sample. It confirms both types are present, but it can't tell us their true proportions in the region.
Mark
So what's the takeaway?
Mimi
Both lineages are circulating in southern Türkiye, and the authors want ongoing surveillance and removal of persistently infected animals.
Il Polso
- Nearly one in five sampled cattle tested positive for pestiviruses, a figure that signals active circulation rather than a distant threat.
- Reproductive disorders and growth retardation carried the highest positivity, pointing to herds where losses are already falling on breeding and productivity.
- Infection early in pregnancy can produce persistently infected calves that shed virus for life, turning a single case into a standing source of spread.
- Five isolates were grown and sequenced, confirming BVDV-1 and placing them in subgenotypes 1b and 1l, both already moving through southern Türkiye.
- The authors are pressing for continued molecular surveillance and removal of persistently infected animals, and the next test is whether wider sequencing shows the same split.
In the Mediterranean province of Burdur, in southern Türkiye, veterinary researchers working across 2021 and 2022 examined blood from 444 unvaccinated cattle, all showing signs of illness, and asked a quiet but consequential question: which strains of a long-known livestock virus are moving through the herds. The answer, that about one animal in five carried a pestivirus and that the isolates belonged to two lineages, subgenotypes 1b and 1l, places a local outbreak within a larger pattern of diversity and endurance in the virus family that has troubled cattle farming for decades. It is a reminder that disease control depends as much on knowing which version of an enemy is present as on knowing that the enemy exists.
Between 2021 and 2022, veterinary researchers in Burdur province, in the Mediterranean south of Türkiye, collected 444 blood serum samples from cattle. None of the animals had been vaccinated against bovine viral diarrhea virus, and every one showed clinical signs consistent with infection. The samples became the foundation for a study of which pestiviruses were moving through the herds of the region.
The virus at the center of the study, BVDV, is a significant threat to livestock health and productivity worldwide. Its effects in cattle range from barely noticeable to severe, touching the respiratory, digestive and reproductive systems. The most troubling outcome comes from infection early in pregnancy, which can produce calves that are persistently infected. Their immune systems tolerate the virus, and they carry and shed it for life, becoming a standing reservoir inside the herd.
The screening found 83 positive samples out of 444, or 18.7 percent. Cattle with reproductive disorders and those with growth retardation showed the highest rates, at about 23 percent each, and the differences between clinical groups were statistically significant. Five representative isolates were then grown in cell culture and confirmed by immunofluorescence. All five were BVDV-1, with two belonging to subgenotype 1b, the most widespread lineage worldwide, and three to subgenotype 1l, a lineage the authors describe as established in Türkiye.
The authors conclude that continued molecular surveillance is worthwhile, along with targeted removal of persistently infected animals, to support regional control programs. The next step is to see whether wider sequencing of positive samples confirms the same mix of 1b and 1l across the province.
Between 2021 and 2022, veterinary researchers in Burdur province, in the Mediterranean region of Türkiye, collected 444 blood serum samples from cattle. None of the animals had been vaccinated against bovine viral diarrhea virus, and all showed clinical signs consistent with infection. The samples became the basis for a study of which pestiviruses are moving through herds in the south of the country.
The virus at the center of it, BVDV, belongs to the genus Pestivirus in the family Flaviviridae. It is a significant threat to livestock health and productivity worldwide. The genus also includes viruses that infect sheep and pigs, and the group as a whole can infect several host species, among them cattle, sheep, goats and wild ruminants. In cattle the disease runs from subclinical to severe, with respiratory, gastrointestinal and reproductive forms.
The most troublesome consequence comes from infection early in pregnancy. It can produce calves that are persistently infected: their immune systems tolerate the virus, and they shed it for life, serving as a standing reservoir for transmission through the herd.
The researchers screened the 444 samples with conventional RT-PCR, aimed at the 5′ untranslated region, a stretch of the genome conserved across pestiviruses. Eighty-three samples tested positive, or 18.7 percent, with a 95 percent confidence interval of 15.3 to 22.6 percent. Positivity was not even across clinical categories; the difference was statistically significant (p = 0.011). Cattle with reproductive disorders had a detection rate of 22.9 percent, and those with growth retardation 22.7 percent, the highest of the groups.
Five representative isolates were then grown in MDBK cells, and the presence of virus was confirmed by direct immunofluorescence assay. Phylogenetic analysis placed all five in BVDV-1. Two fell within subgenotype 1b, and three within subgenotype 1l.
Those two labels carry some background. BVDV-1 is genetically diverse, with at least 24 subgenotypes, labeled 1a through 1x. Subgenotype 1b is the most prevalent worldwide. Subgenotype 1l has recently emerged as a predominant lineage in certain regions, and the authors describe it as an endemic lineage in Türkiye, where BVDV-1 subtypes, BVDV-2 and HoBi-like viruses have all been reported. The Burdur isolates confirm that 1b and 1l are both circulating in southern Türkiye.
The authors conclude that continued molecular surveillance is worthwhile, along with targeted removal of persistently infected animals, to support regional control programs. The next step is to see whether wider sequencing of positive samples shows the same split between 1b and 1l.
Citazioni salienti
The findings confirm circulation of BVDV-1 subgenotypes 1b and 1l in southern Türkiye and support continued molecular surveillance and targeted removal of persistently infected animals.— Study authors, Nature
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