Texas A&M spotlights extreme immune gene diversity in herring
Bottom line
Texas A&M researchers say Atlantic herring carry an unusually rich set of immune-gene variants, with diversity in major histocompatibility complex class II genes that appears to exceed what’s been reported in any other vertebrate, including humans. The finding comes from work led by Leif Andersson and Minal Jamsandekar at Texas A&M and collaborators, and builds on long-read genome sequencing that identified nine MHC class II loci across four chromosomes, including a highly polymorphic DA lineage and a less variable DB lineage. The team argues that herring’s vast population size, dense schooling behavior, copy number variation, and long-term pathogen-driven balancing selection likely helped produce this exceptional diversity. Texas A&M framed the discovery as evidence of how natural selection shaped immune defenses in one of the world’s most abundant vertebrates. (meetings.cshl.edu)
Why it matters: For veterinary and comparative biomedical professionals, the study adds to a growing body of work positioning Atlantic herring as a useful model for understanding how immune systems evolve under sustained pathogen pressure. The findings may be most relevant not as a direct clinical advance, but as a comparative immunology signal: immune loci with extensive copy number variation and extreme allelic diversity can be missed or misread by standard short-read genomic approaches, a point the same research group highlighted in a 2024 BMC Genomics paper on herring immune-trait loci. That has implications for how researchers study disease resilience, host-pathogen interactions, and immune-gene architecture across species, including animals of veterinary interest. (pubmed.ncbi.nlm.nih.gov)
What to watch: The herring MHC class II work was posted as a bioRxiv preprint on June 8, 2025, and was later described in a 2026 conference abstract as being under revision at Science Advances, so the next key step is peer-reviewed publication and any follow-on work testing how this diversity affects pathogen resistance in practice. (meetings.cshl.edu)
Key facts
- Species
- Atlantic herring
- Finding
- Researchers say herring have extraordinary diversity in MHC class II immune genes, exceeding what has been reported in humans and other vertebrates.
- Study type
- Long-read whole-genome sequencing study
- Sample size
- 14 herring
- Regions sampled
- Three geographic regions in the Atlantic Ocean and Baltic Sea
- MHC class II loci
- Nine loci across four chromosomes
- Lineages
- DA lineage, highly polymorphic; DB lineage, relatively non-polymorphic
- Preprint date
- June 8, 2025
- Status
- Described as under revision at Science Advances
Texas A&M researchers are highlighting a striking comparative immunology finding in Atlantic herring: the fish appear to harbor extraordinary diversity in MHC class II immune genes, with variation the team says surpasses that reported in humans and other vertebrates. The work is tied to a long-read sequencing study led by Minal Jamsandekar, Leif Andersson, and collaborators, and Texas A&M’s coverage presents it as a case of natural selection shaping immune defenses in a species that lives in massive, pathogen-exposed schools. (meetings.cshl.edu)
The announcement fits into a longer Texas A&M and Uppsala-led research program that has used Atlantic herring to study adaptation, population structure, and complex genomic variation. Earlier work from the group examined herring population genomics for fishery management, ecological adaptation across the Atlantic and Baltic regions, and structural variation tied to adaptation. A 2024 BMC Genomics paper from the same broader effort also found elevated diversity and copy number variation at immune-trait loci in Atlantic and Pacific herring, suggesting these regions are unusual even before this latest MHC class II analysis. (vetmed.tamu.edu)
The core new study, available as a preprint, used PacBio HiFi long-read whole-genome sequencing from 14 herring collected from three geographic regions in the Atlantic Ocean and Baltic Sea. According to the abstract and Texas A&M repository materials, the researchers identified nine MHC class II loci distributed across four chromosomes. They describe two lineages: a highly polymorphic DA lineage and a relatively non-polymorphic DB lineage, organized as alpha-beta gene pairs. The DA genes showed especially high nucleotide diversity in exon 2, strong positive-selection signals, and copy number variation, while predicted highly polymorphic amino acids clustered in the peptide-binding cleft, consistent with functional immune selection. (meetings.cshl.edu)
The researchers also report that two of the most polymorphic loci formed distinct allelic “supertypes,” with strong sequence similarity within each supertype and substantial divergence between them. Most haplotypes carried genes from different supertypes, which the authors say would preserve a broad MHC class II repertoire within individual fish. They further found a significant nonrandom association between DAA and DAB alleles within supertypes, which they interpret as evidence that paired alpha and beta chains have coevolved in ways that shape peptide presentation. (meetings.cshl.edu)
Outside reaction appears limited so far, likely because the work is still in the preprint-to-publication stage. But the team has presented the findings in multiple scientific venues, including a 2025 Cold Spring Harbor meeting abstract and a 2026 conference abstract that repeated the central claim that herring MHC class II genes are among the most polymorphic yet described in vertebrates. That consistency across the preprint, Texas A&M repository entry, and conference materials suggests the group is standing firmly behind the result while the manuscript moves through peer review. (meetings.cshl.edu)
Why it matters: For veterinary professionals, this is less about immediate clinical application in companion animals and more about the comparative biology of immune resilience. MHC class II genes are central to antigen presentation and adaptive immune responses, so an extreme natural example of diversity offers a useful model for studying host-pathogen coevolution, balancing selection, and the genomic architecture of disease defense. It also reinforces a technical point with broader research relevance: complex immune loci with copy number variation may be poorly resolved by conventional short-read sequencing, which could matter for immunogenetics work in fish, wildlife, livestock, and other veterinary species. (pubmed.ncbi.nlm.nih.gov)
There’s also a population-health angle. Atlantic herring are one of the most abundant vertebrates on Earth and a major ecological and commercial species, so understanding immune diversity in these fish could eventually inform how researchers think about disease dynamics in dense animal populations. Earlier Atlantic herring studies have already shown that the species is a powerful model for adaptation because its large population size limits genetic drift and preserves signatures of selection. This new work extends that idea into immunogenetics. (elifesciences.org)
What to watch: The immediate next milestone is formal peer-reviewed publication; the study was posted to bioRxiv on June 8, 2025, and later described in a 2025 dissertation summary as “in revision” at Science Advances. After that, the key question will be whether follow-up studies can connect this remarkable genomic diversity to measurable differences in pathogen response, disease susceptibility, or population resilience. (uu.diva-portal.org)