Effect of sow mass vaccination against Mycoplasma hyopneumoniae on the humoral immune response of newborn piglets.

Pneumonia caused by Mycoplasma (M.) hyopneumoniae is one of the major respiratory diseases in swine production. Commercial vaccines for M. hyopneumoniae are widely used in weaned piglets to reduce lung lesions and clinical signs in the downstream flow; however, no information regarding the effect of mass immunization of the breeding herd is available. The aim of this work was to evaluate a mass vaccination protocol for M. hyopneumoniae on the humoral response of sows and their offspring 24 h post-partum (trial registration number 40156). A total of 52 sows from two different farms (13 primiparous and 13 multiparous sows on each farm), one with mass vaccination (MVF) and one without mass vaccination against M. hyopneumoniae (control farm (CF)) were enrolled in this study. Five piglets from each litter were selected, resulting in 260 piglets. Blood was collected from sows and piglets 24 h post-partum for M. hyopneumoniae antibody detection by ELISA. The results showed that primiparous sows from MVF had higher antibody titers compared to multiparous sows of the same farm, and multiparous and primiparous sows from the CF. Similar results were evidenced in their offspring. The findings of this study suggest that mass vaccination results in a more robust serologic response on primiparous sows, which could be the main target of vaccination strategies for the breeding herd.

Cardiotoxic Effects of Micrurus surinamensis (Cuvier, 1817) Snake Venom.

Micrurus surinamensis is a coral snake from the Elapidae family of wide distribution in Amazonia Forest. Its venom contains neurotoxins that induce muscular and respiratory paralysis; however, its cardiovascular action is not yet characterized. The aim of this study was to investigate the cardiotoxic effects caused by M. surinamensis poisoning in rodents. Twelve guinea pigs (Cavia porcellus) were distributed in two groups (n = 6) named as control and envenomed. The control group received 0.2 ml of PBS/BSA via intramuscular injection (IM), while envenomed animals received 0.75 µg of venom per g of body weight, also via IM. Electrocardiographic examination (ECG) and biochemical serum tests were conducted before and 2 h after inoculation. ECG of the envenomed animals revealed severe progressive arrhythmias including atrioventricular block, supraventricular, and ventricular extrasystoles. Serum biochemistry showed significant increase in CK, CK-MB, and LDH enzymes corroborating the skeletal and cardiac muscle damage. Myonecrosis and degeneration were observed in both skeletal and heart muscle; nevertheless, transmission electron microscopy revealed cardiac muscle fibers fragmentation. In conclusion, M. surinamensis venom has a potent cardiotoxic activity eliciting arrhythmogenic effects and heart damage after only 2 h of envenomation.

Vaccinia virus Transmission through Experimentally Contaminated Milk Using a Murine Model.

Bovine vaccinia (BV) is a zoonosis caused by Vaccinia virus (VACV), which affects dairy cattle and humans. Previous studies have detected the presence of viable virus particles in bovine milk samples naturally and experimentally contaminated with VACV. However, it is not known whether milk contaminated with VACV could be a route of viral transmission. However, anti-Orthopoxvirus antibodies were detected in humans from BV endemic areas, whom had no contact with affected cows, which suggest that other VACV transmission routes are possible, such as consumption of contaminated milk and dairy products. Therefore, it is important to study the possibility of VACV transmission by contaminated milk. This study aimed to examine VACV transmission, pathogenesis and shedding in mice orally inoculated with experimentally contaminated milk. Thirty mice were orally inoculated with milk containing 107 PFU/ml of VACV, and ten mice were orally inoculated with uncontaminated milk. Clinical examinations were performed for 30 consecutive days, and fecal samples and oral swabs (OSs) were collected every other day. Mice were euthanized on predetermined days, and tissue and blood samples were collected. Nested-PCR, plaque reduction neutralization test (PRNT), viral isolation, histopathology, and immunohistochemistry (IHC) methods were performed on the collected samples. No clinical changes were observed in the animals. Viral DNA was detected in feces, blood, OSs and tissues, at least in one of the times tested. The lungs displayed moderate to severe interstitial lymphohistiocytic infiltrates, and only the heart, tonsils, tongue, and stomach did not show immunostaining at the IHC analysis. Neutralizing antibodies were detected at the 20th and 30th days post infection in 50% of infected mice. The results revealed that VACV contaminated milk could be a route of viral transmission in mice experimentally infected, showing systemic distribution and shedding through feces and oral mucosa, albeit without exhibiting any clinical signs.