Circular Rep-Encoding Single-Stranded DNA Sequences in Milk from Water Buffaloes (Bubalus arnee f. bubalis)

Abstract

Isolation and characterization of circular replicase-encoding single-stranded (ss) DNA from animal, plant and environmental samples are rapidly evolving in virology. We detected 21 circular DNA elements, including one genomoviral sequence, in individual milk samples from domesticated Asian water buffaloes (Bubalus arnee f. bubalis). Most of the obtained genomes are related to Sphinx 1.76 and Sphinx 2.36 sequences and share a high degree of similarity to recently published circular DNAs—named BMMF (bovine meat and milk factors)—that have been isolated from commercial milk, as well as from bovine serum. Characteristic features such as rep genes, tandem repeats and inverted repeats were detected. These BMMF have recently been found to be present in taurine-type dairy cattle breeds descending from the aurochs (Bos primigenius). Importantly, the occurrence of BMMF has been linked to the higher incidence of colorectal and breast cancer in North America and Western Europe compared with Asia. This is the first report of circular ssDNA detected in milk from the domesticated form of the wild Asian water buffalo (B. arnee) belonging to the subfamily Bovinae. This novelty should be taken into account in view of the above-mentioned cancer hypothesis.

Identification and Characterization of Circular Single-Stranded DNA Genomes in Sheep and Goat Milk

“…In contrast, flock C comprised 13% (2/15) positive individual samples only. Results obtained from sheep and goat milk on the flock level thus markedly differ from the recently published data on water buffalo milk: (i) both water buffalo herds under study were affected and (ii) 56% of the animals from herd 1 and 42% from herd 2 tested positive for full-length sequences [25]. Although three out of 40 individual goat milk samples yielded amplicons of the expected size and sequence with at least one primer pair during PCR screening, we failed to retrieve full-length circular genomes from any of them.…”

“…Although three out of 40 individual goat milk samples yielded amplicons of the expected size and sequence with at least one primer pair during PCR screening, we failed to retrieve full-length circular genomes from any of them. This discrepancy has already been observed when water buffalo milk was assayed [25] and again underlines the importance not to rely on the presence of sub-genomic amplicons to categorize an individual as positive. In contrast to the individual samples from the goat farms, four full-length genomes were recovered from goat milk at retail (GmGV9; GmI2, GmI5 and GmI6).…”

“…Beside "taurine" cattle, "zebuine" cattle, water buffaloes and small ruminants contribute to the worldwide milk supply [24]. In a recently published study, we showed the occurrence of circular ssDNA and a gemycircularvirus in water buffalo milk [25]. Data from studies focussing on domestic livestock are scarce and display a still narrow basis for a risk assessment concerning potential adverse effects on human health.…”

Potential Pathogenic Impact of Cow’s Milk Consumption and Bovine Milk-Derived Exosomal MicroRNAs in Diffuse Large B-Cell Lymphoma

“…These infectious agents share characteristics of both bacterial plasmids and known viruses [ 253 ]. Recently, circular single-stranded DNA genomes have been identified in the milk of sheep and goats [ 254 ] as well as the milk of water buffaloes [ 255 ]. Thus, dairy cows, sheep, goats, and water buffaloes add to the dispersal of CRESS viruses and circular ssDNA elements, which enter the human food chain via milk consumption [ 248 , 249 , 254 , 255 ].…”

Bovine Meat and Milk Factors (BMMFs): Their Proposed Role in Common Human Cancers and Type 2 Diabetes Mellitus

“…Less conspicuous observations exist in a few other countries. Recently, however, BMMF 1 and 2 sequences were demonstrated in milk from a different aurochs-derived bovine species: water buffalos (Bubalus arnee f. bubalis) [19].…”