Bovine Meat and Milk Factors (BMMFs) are circular, single-stranded

DNA molecule Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ...

s (cssDNAs) originally found in

beef Beef is the culinary name for meat from cattle (''Bos taurus''). Beef can be prepared in various ways; Cut of beef, cuts are often used for steak, which can be cooked to varying degrees of doneness, while trimmings are often Ground beef, grou ...

and

cow's milk Milk is a white liquid food produced by the mammary glands of lactating mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digest solid food. Milk contains many nutr ...

which have been linked to the development of cancer—particularly

colorectal The large intestine, also known as the large bowel, is the last part of the gastrointestinal tract and of the digestive system in tetrapods. Water is absorbed here and the remaining waste material is stored in the rectum as feces before being rem ...

and

breast cancer Breast cancer is a cancer that develops from breast tissue. Signs of breast cancer may include a Breast lump, lump in the breast, a change in breast shape, dimpling of the skin, Milk-rejection sign, milk rejection, fluid coming from the nipp ...

. They are formerly known as Slow Progressive Hidden INfections of variable X (SPHINX). Similar molecules have since been found in a much wider range of food. BMMF/SPHINX sequences are able to copy themselves in animal cells. They encode functional proteins that are expressed in some animal cells. Every BMMF/SPHINX contains at least a "Rep"

open reading frame In molecular biology, reading frames are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible reading frames ...

, which encodes a replication endonuclease that, in HEK 293TT cells, acts to replicate and retain the cssDNA. BMMF/SPHINX sequences are divided into four

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

s. Clades 1, 2, and 3 share sequence similarity with the plasmids of ''

Acinetobacter baumannii ''Acinetobacter baumannii'' is a typically short, almost round, rod-shaped (coccobacillus) Gram-negative bacterium. It is named after the bacteriologist Paul Baumann. It can be an opportunistic pathogen in humans, affecting people with compromis ...

''. (''A. baumanii'' regularly produces

outer membrane vesicles Outer membrane vesicles (OMVs) are vesicles released from the outer membranes of Gram-negative bacteria. While Gram-positive bacteria release vesicles as well, those vesicles fall under the broader category of bacterial membrane vesicles (MVs ...

containing these plasmids, and animal cells are known to take up these vesicles.) Clade 4 shares sequence similarity with Gemycircularvirus.

Health research

The potential connection between BMMFs and cancer has been made based on assessments of epidemiological data and the investigation of antibodies in human serum. Research has also suggested a potential link between BMMFs and

neurodegenerative diseases A neurodegenerative disease is caused by the progressive loss of neurons, in the process known as neurodegeneration. Neuronal damage may also ultimately result in their death. Neurodegenerative diseases include amyotrophic lateral sclerosis, mul ...

such as

multiple sclerosis Multiple sclerosis (MS) is an autoimmune disease resulting in damage to myelinthe insulating covers of nerve cellsin the brain and spinal cord. As a demyelinating disease, MS disrupts the nervous system's ability to Action potential, transmit ...

. At the end of 2017, evidence was presented that BMMFs in human cells show long-term survival, through the identification of BMMFs' RNA and protein products. In February 2019, evidence was presented of a previously unknown

infectious agent In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ. The term ...

in the blood serum and milk of Eurasian cattle that could indirectly trigger the development of colorectal cancer.

Abandoned theories

For a short period the SPHINX DNAs were believed to have some connection with

transmissible spongiform encephalopathy Transmissible spongiform encephalopathies (TSEs), also known as prion diseases, are a group of progressive, incurable, and fatal conditions that are associated with the prion hypothesis and affect the brain and nervous system of many animals, in ...

following its isolation from CJD and scrapies patients. The author of the article has since moved on to a viral hypothesis for TSE.

Health research

Abandoned theories

References

Further reading