COVID-19 mRNA Vaccination in Lactation: Assessment of Adverse Events and Vaccine Related Antibodies in Mother-Infant Dyads.

Background: Data regarding symptoms in the lactating mother-infant dyad and their immune response to COVID-19 mRNA vaccination during lactation are needed to inform vaccination guidelines. Methods: From a prospective cohort of 50 lactating individuals who received mRNA-based vaccines for COVID-19 (mRNA-1273 and BNT162b2), blood and milk samples were collected prior to first vaccination dose, immediately prior to 2nd dose, and 4-10 weeks after 2nd dose. Symptoms in mother and infant were assessed by detailed questionnaires. Anti-SARS-CoV-2 antibody levels in blood and milk were measured by Pylon 3D automated immunoassay and ELISA. In addition, vaccine-related PEGylated proteins in milk were measured by ELISA. Blood samples were collected from a subset of infants whose mothers received the vaccine during lactation (4-15 weeks after mothers' 2nd dose). Results: No severe maternal or infant adverse events were reported in this cohort. Two mothers and two infants were diagnosed with COVID-19 during the study period before achieving full immune response. PEGylated proteins were not found at significant levels in milk after vaccination. After vaccination, levels of anti-SARS-CoV-2 IgG and IgM significantly increased in maternal plasma and there was significant transfer of anti-SARS-CoV-2-Receptor Binding Domain (anti-RBD) IgA and IgG antibodies to milk. Milk IgA levels after the 2nd dose were negatively associated with infant age. Anti-SARS-CoV-2 IgG antibodies were not detected in the plasma of infants whose mothers were vaccinated during lactation. Conclusions: COVID-19 mRNA vaccines generate robust immune responses in plasma and milk of lactating individuals without severe adverse events reported.

In vitro assessment of the effects of temperature on phagocytosis, reactive oxygen species production and apoptosis in bovine polymorphonuclear cells.

Heat stress exerts a direct negative effect on farm animal health, triggering physiological responses. Environmental high temperature induces immunosuppression in dairy cows, increasing the risk of mastitis and milk somatic cell counts. The influence of heat stress on leukocytes activities has not been fully elucidated. The present in vitro study was aimed at assessing whether the exposure to temperature simulating conditions of severe whole body hyperthermia affects defensive functions of bovine blood polymorphonuclear cells. Blood was collected from seven clinically healthy, multiparous, late lactating Holstein cows. After isolation, PMN were incubated at either 39 or 41°C. Phagocytosis, respiratory burst and apoptosis were then investigated. The selected temperatures of 39°C or 41°C mimicked conditions of normothermia or severe heat stress, respectively. Phagocytosis assay was carried out by measuring the fluorescence of phagocyted fluorescein-labelled E. coli bioparticles. The modulation of oxidative burst activity was studied by the cytochrome C reduction method. Apoptosis was determined by measuring the activities of two enzymes that play an effector role in the process, namely Caspase-3 and Caspase-7. Statistical analyses were performed using SPSS 22.0. A Student t-test for paired samples and a Generalised Estimating Equation were used based on data distribution. The phagocytosis rate was reduced (-37%, P<0.01) when PMN were incubated for 2h at 41°C, when compared to phagocytosis rate measured at 39°C. The oxidative burst, as determined by extracellular production of reactive oxygen species (ROS), was also reduced by the exposure of cells to 41°C compared to 39°C. Such reduction ranged between -2 and -21% (P<0.05). Apoptosis rate was not affected by different temperatures. The results reported in this study suggest that phagocytosis and ROS production in PMN exposed to severe high temperature are impaired, partially explaining the higher occurrence of infections during periods of hot weather.

Assessment of immune response in periparturient dairy cows using ex vivo whole blood stimulation assay with lipopolysaccharides and carrageenan skin test.

The transition period is known to be the most critical phase in the life of high yielding dairy cow. Changes in the immune functions have been observed during the transition period which may account for the onset of clinical and subclinical (e.g. inflammatory response) problems at calving or at the beginning of lactation however this relationship has not yet been adequately investigated. Thus, to establish the potential of the periparturient dairy cow's immune system to respond to stimuli, two challenges [an ex vivo whole blood stimulation assay (WBA) with lipopolysaccharides and a carrageenan skin test (CST)] were performed in addition to characterizing the metabolic and inflammatory profile. The WBA was performed using 0, 0.01 and 5 µg LPS/mL on whole blood and CST was administered by subcutaneous injection of 0.7 mL solution containing 4.2mg of carrageenan to the shoulder region of the cows. These tests were performed on 10 Holstein-Friesian cows at -45 ± 2, -20 ± 2, -3, 3, 7, 28 ± 2 days from parturition (DFP). Cows were also monitored for health status, body condition score, milk yield. The results demonstrate a higher production of IL-1ß and IL-6 from leukocytes after LPS stimulation around calving (from -3 to 3 DFP) compared to -45 DFP (P < 0.05). Moreover, IL-6 (but not IL-1ß) was able to reach close to the maximum response at the lower stimulus intensity (0.01 µg LPS/mL), maintaining a higher response over a longer time in early lactation. The release of higher levels of IL-6 in the transition period, with low LPS dose, suggests its crucial role in the regulation of inflammatory response around calving. The response of cows to CST decreased a few days before calving (-3 DFP) compared with response at -45 and 28 DFP (P<0.05), and remained low in the first week of lactation. This result suggests the reduction of the functionality of some vascular factors, which decreases diapedesis. Overall, the WBA and CST tests confirm changes in immunocompetence around calving. These tests are able to better describe the changes of the innate immune response at a local and systemic level, mainly when combined with conventional metabolic and inflammatory indices.

Severity of E. coli mastitis is mainly determined by cow factors.

Intramammary infections of dairy cows with Gram-positive bacteria such as Staphylococcus aureus (major cause of mastitis) have received a lot of attention because of their major economic impact on the dairy farm through production losses induced by an increase in somatic cell count. Management strategies, including greater awareness for efficient milking and hygienic measures, have limited the spread of Gram-positive bacteria and resulted in a significant decrease of proportion of S. aureus isolates and subclinical mastitis worldwide. Other organisms such as coliform subspecies and Streptococcus uberis, both environmental bacteria that cause clinical mastitis, have received less attention. Escherichia coli causes inflammation of the mammary gland in dairy cows around parturition and during early lactation with striking local and sometimes severe systemic clinical symptoms. This disease affects many high producing cows in dairy herds and may cause several cases of death per year in the most severe cases. It is well known that bacterial, cow and environmental factors are interdependent and influence mastitis susceptibility. Many studies, executed during the last decade, indicate that the severity of E. coli mastitis is mainly determined by cow factors rather than by E. coli pathogenicity. During E. coli mastitis, the host defense status is a cardinal factor determining the outcome of the disease. Today, we know that the neutrophil is a key factor in the cows' defense against intramammary infection with E. coli. Effective elimination of the pathogen by neutrophils is important for the resolution of infection and the outcome of E. coli mastitis. This review is a compilation of some major findings over the last 15 years concerning mainly host factors that modulate and influence neutrophil function and the mammary inflammatory reaction. The individual chapters address: virulence factors of E. coli strains, how neutrophils kill E. coli, connection between endotoxins, tumor necrosis factor-alpha and nitric oxide, severity classification of E. coli mastitis, lifespan of neutrophils, host factors that influence severity, tissue damage and production loss.

Effects of nutritional stress during lactation on immunity costs and indices of future reproduction in Iberian red deer (Cervus elaphus hispanicus).

Nutrition may affect the balance between immunity and traits such as reproduction or growth. This study examines the effect of low nutrient availability on immunity indices and lactation in captive Iberian red deer. Twelve hinds and their calves were allotted to a food-restricted (50-60% daily energy requirements) or a control group just after calving. Low calorie intake exerted a greater effect on the immunity of calves than on that of hinds. Whereas no difference was found for hinds, calves of the low intake group showed mean immunoglobulin (Ig) levels higher than those on a standard diet, which suggests that Ig level may indicate the level of fighting against pathogens. Serum indices of body condition in calves showed generally positive correlations with milk nutrient production. In contrast, Ig level within each group showed a pattern inverse to that of the other group for early lactation: in the standard diet group, the greater the milk nutrient produced and calf growth, the lower the Ig level; this relationship was inversed in the low-nutrition group. These results suggest that, on a standard diet, high Ig levels may indicate high levels of pathogen fighting paired to poorer body condition. Inversely, once the first barriers of innate immunity are surpassed, only those calves on the low-nutrition group with greater resources would be able to spend more resources to fight infection. Thus, low calorie intake might boost its slowing effect on growth by increasing the costs of infection fighting.

Position of the American Dietetic Association: breaking the barriers to breastfeeding.

It is the position of the American Dietetic Association (ADA) that broad-based efforts are needed to break the barriers to breastfeeding initiation and duration. Exclusive breastfeeding for 6 months and breastfeeding with complementary foods for at least 12 months is the ideal feeding pattern for infants. Increases in initiation and duration are needed to realize the health, nutritional, immunological, psychological, economical, and environmental benefits of breastfeeding. Breastfeeding initiation rates have increased, but cultural barriers to breastfeeding, especially against breastfeeding for 6 months and longer, still exist. Gaps in rates of breastfeeding based on age, race, and socioeconomic status remain. Children benefit from the biologically unique properties of human milk including protection from illness with resulting economic benefits. Mother's benefits include reduced rates of premenopausal breast and ovarian cancers. Appropriate lactation management is a critical component of successful breastfeeding for healthy women. Lactation support and management is even more important in women and children with special needs caused by physical or developmental disability, disease, or limited resources. Dietetics professionals have a responsibility to support breastfeeding through appropriate education and training, advocacy, and legislative action; through collaboration with other professional groups; and through research to eliminate the barriers to breastfeeding.

Assessment of phagocytic capacity and opsonic activity in blood and mammary secretions during lactation in sows.

The objective of this study was to determine whether phagocytic capacity and opsonic activity in blood and mammary secretions of sows are impaired at parturition compared with later on during lactation. The study comprised eight primiparous sows (Landrace x Yorkshire) free from clinical signs of disease. Blood and mammary secretion samples were collected within 48 h of parturition and 7 and 16 days after parturition. Numbers and proportion of polymorphonuclear neutrophils (PMN) were determined in blood and mammary secretions. Phagocytic capacity was assessed in whole blood and in a cell suspension derived from mammary secretions. Opsonic activity was assessed in serum and i cell-depleted, skimmed mammary secretions. The two assays were based on chemiluminescence, both having zymosan and Escherichia coli as target particles. Numbers and proportion of PMN in mammary secretions were higher (P < 0.05) at parturition than later on during lactation. A parturition, phagocytic capacity in cell suspensions derived from mammary secretions was higher for both (P < 0.05) and E. coli (P < 0.1). However, when phagocytic capacity was related to the number of PMN in the suspension no such difference was observed. The opsonic activity in cell-depleted, skimmed mammary secretions at parturition was lower (P < 0.05) for zymosan but not for E. coli. None of the described variations were reflected in blood or serum. The findings of this study do not unequivocally support the theory that an immune suppression at parturition in the sow can help explain the increased incidence of coliform mastitis at that time.