Antibiotic treatment of cows may increase their methane emissions
In a small study, antibiotic treatment of cows nearly doubled emissions of methane, a potent greenhouse gas, from their manure, suggesting that worries about antimicrobial resistance may not be the only reason to use caution with antibiotics in farm animals, according to a report today in the Journal of the Royal Society B.
In the experiment, conducted in Finland, an international team of researchers treated five cows with tetracycline for 3 days and used five other cows as controls. A day's worth of fresh dung was collected beginning an hour after the last antibiotic dose, and dung emissions of carbon dioxide, methane, and nitrous oxide were measured.
The team found no significant difference in carbon dioxide or nitrous oxide emissions between the treated and untreated cows, but about 80% more methane was emitted from the manure of treated cows, the report says.
The researchers also placed dung beetles in some of the dung samples and observed that antibiotic treatment "restructured" the beetles' microbiota, though it did not affect the insects' size or numbers.
The authors said their study appears to be the first to show an increase in methane emissions associated with antibiotic treatment in livestock. They observe that tetracycline and some other antibiotics are less effective against archaea—primitive, nonbacterial single-celled microbes—than against bacteria. They propose that by suppressing bacteria in the gut and in dung, antibiotics enable methane-producing archaea to outcompete bacteria for hydrogen, thus increasing their methane output.
Methane emissions from cattle manure are typically lower than those from cattle belching, but they still make up a sizable share of the total, the researchers write. They suggest that future research should focus on antibiotic effects on methane from belching.
May 25 J Royal Soc B abstract
Study finds MERS-CoV antibodies in camel calves for first 5 to 6 months
Camel calves lose maternal MERS-CoV antibodies about 5 to 6 months after birth and are susceptible to infection, indicating a possible window for vaccination, according to a study today in Emerging Infectious Diseases.
German and United Arab Emirates (UAE) scientists monitored levels of antibodies specific to MERS-CoV (Middle East respiratory syndrome coronavirus) in 11 camel mothers and their calves for 1 year after birth. The animals were part of a 4,500-camel herd in the UAE, and the calves were born in early June 2014. The researchers collected nasal swabs and serum specimens on the day of birth, after 1 week, after 1 month, and then every month after that.
On the day of calving, MERS-specific antibodies were high in all camel mothers studied but could not be detected in the calves. A week later, however, all 11 camel calves had high MERS-CoV–specific antibody levels. At 5 to 6 months after birth MERS-CoV antibodies were not detected in 6 calves and were at low levels in the other 5—at 1:20 to 1:40 neutralizing titers.
The researchers also tested for MERS-CoV shedding in nasal swab specimens and detected sporadic shedding on days 7 and 30 in some calves. At 6 months, 2 of the 11 calves had detectable RNA in their blood, indicating an active infection.
The authors conclude, "Our findings have important implications for the prevention of human infections through camel herd management and camel vaccination. Camel breeding, even if involving a small number of newborn animals, should be classified as a risk for human acquisition of MERS-CoV."
May 25 Emerg Infect Dis study
NIAID awards Soligenix $3.2 million for animal studies of ricin vaccine
The National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health has exercised an option to fund animal efficacy and toxicology studies for Soligenix's RiVax ricin vaccine as a bioterror preparedness measure, the company said in a news release today.
The option provides the company $3.2 million in additional funding, bringing Soligenix's contract with the NIAID up to $16.7 million. If all contract options are exercised to advance a heat-stable RiVax to the approval stage, the total award will be $24.7 million, the company said.
Ricin is a plant toxin and potential biological weapon because of its stability, potency, and availability as a byproduct of castor oil production. It comes in many forms such as powder, mist, or pellet and can also be dissolved in liquid.
Phase 1 trials of RiVax with and without an immune-boosting adjuvant demonstrated safety and immune response in adult volunteers, according to the release.
May 25 Soligenix news release