The influence of year, laying date, egg fertility and incubation, individual hen, hen age and mass and clutch size on maternal immunoglobulin Y concentration in captive Steller's and spectacled eider egg yolk

An mRNA vaccine provides effective protection against Duck Tembusu Virus infection

As an emerging flavivirus, Duck Tembusu virus (DTMUV) causes severe neurological disorder and acute egg drop syndrome in poultry. Herein, we report the development of a highly effective mRNA vaccine against DTMUV using lipid nanoparticle (LNP) delivery technology. We engineered an mRNA construct encoding the pre-membrane (prM) and envelope (E) proteins of DTMUV, with an upstream signal peptide to enhance secretion. Two doses of our mRNA vaccine elicited robust neutralizing antibody titers and conferred 100% protection against challenge with a prevalent virulent DTMUV strain. Notably, in a head-to-head comparison, the neutralizing antibody titers induced by our mRNA vaccine were approximately 40-fold of a commercial live-attenuated vaccine (FX2010-180P). Importantly, our mRNA vaccine demonstrated efficient maternal antibody transfer via egg yolk deposition, indicating the potential for protecting offspring through maternal immunity. These findings demonstrate the superiority of our mRNA vaccine platform, as well as the feasibility of applying mRNA vaccines in poultry.

The protective effect of specific yolk antibody against nervous necrosis virus infection in Mandarin fish(Siniperca chuatsi)

Nervous necrosis virus (NNV), a member of the Nodavirus genus, is a highly contagious disease that is found all over the world. As of right now, there aren't many reliable commercial vaccines available to combat this infection. In a previous study, we isolated a Mandarin fish (Siniperca chuatsi)-derived NNV strain, tentatively named MFNNV. By immunizing hens with MFNNV recombinant capsid protein (CP), this study produced high-purity anti-MFNNV yolk antibodies. According to the ELISA results, the purified anti-MFNNV IgY titer peaked at week 8 after the first vaccination; western blotting and indirect immunofluorescence results showed that IgY could act as a primary antibody to specifically recognize recombinant CP and virus particles. At the cellular level, specific IgY significantly reduced the appearance of vacuolated cytopathic effect in GS cells after incubation with an equal volume of virus compared with non-specific IgY. Mandarin fish was fed diets supplemented with anti-MFNNV IgY or non-specific IgY at 33 % (w/w) for 7 days prior to artificial infection with MFNNV. On the 14th day of artificial infection with MFNNV, the mortality rate was 53.3 % in the specific group and 83.3 % in the nonspecific group, and the relative protection rate of the specific IgY group was about 36 % compared with that of the nonspecific IgY group. In histopathological analysis, vacuolizing lesions were observed in the brain tissues of Mandarin fish in the non-specific group, whereas only slight vacuolization was observed in the brain tissues of the specific group. Further analysis revealed that compared with the non-specific group, the MFNNV-CP gene expression in the eyes as well as the brain of Mandarin fish in the specific group showed a significant decrease, and the mRNA expression levels of immune-related factors, such as TNF-α, IFN-h, IL-1, IL-8, Mx proteins, and IgM in the spleen, liver, kidney, and hindgut tissues of the specific group also showed a decrease of varying degrees, suggesting that oral administration of specific IgY could neutralize virus and reduce the immune responses as well as tissue pathological damage induced by the Nervous necrosis virus. Consequently, we suggested that IgY could protect Mandarin fish from MFNNV infection by acting as a passive immunological measure.

Egg viability and egg mass underlie immune tradeoffs and differences between urban and rural lizard egg yolk physiology

Urbanization can cause innumerable abiotic and biotic changes that have the potential to influence the ecology, behavior, and physiology of native resident organisms. Relative to their rural conspecifics, urban Side-blotched Lizard (Uta stansburiana) populations in southern Utah have lower survival prospects and maximize reproductive investment via producing larger eggs and larger clutch sizes. While egg size is an important predictor of offspring quality, physiological factors within the egg yolk are reflective of the maternal environment and can alter offspring traits, especially during energetically costly processes, such as reproduction or immunity. Therefore, maternal effects may represent an adaptive mechanism by which urban-dwelling species can persist within a variable landscape. In this study, we assess urban and rural differences in egg yolk bacterial killing ability (BKA), corticosterone (CORT), oxidative status (d-ROMs), and energy metabolites (free glycerol and triglycerides), and their association with female immune status and egg quality. Within a laboratory setting, we immune challenged urban lizards via lipopolysaccharide injection (LPS) to test whether physiological changes associated with immune system activity impacted egg yolk investment. We found urban females had higher mite loads than rural females, however mite burden was related to yolk BKA in rural eggs, but not urban eggs. While yolk BKA differed between urban and rural sites, egg mass and egg viability (fertilized vs. unfertilized) were strong predictors of yolk physiology and may imply tradeoffs exist between maintenance and reproduction. LPS treatment caused a decrease in egg yolk d-ROMs relative to the control treatments, supporting results from previous research. Finally, urban lizards laid a higher proportion of unfertilized eggs, which differed in egg yolk BKA, CORT, and triglycerides in comparison to fertilized eggs. Because rural lizards laid only viable eggs during this study, these results suggest that reduced egg viability is a potential cost of living in an urban environment. Furthermore, these results help us better understand potential downstream impacts of urbanization on offspring survival, fitness, and overall population health.

Immune parameters in different age classes of captive male Steller's eiders (Polysticta stelleri)

The immune system is important for host defense against antigens, but little is known about Steller's eider (Polysticta stelleri) immunology. This study compared hematological parameters, serum protein levels, lymphocyte proliferation, heat shock protein levels and oxidative damage in four different age classes of captive male Steller's eiders. The hatch year cohort had significantly higher total white blood cell and lymphocyte counts. The second year cohort had significantly higher albumin, alpha globulins and lymphocyte proliferation, and significantly lower beta globulin levels. The 9 year old males had a significantly higher IgY:IgY(ΔFc) ratio. The oldest eiders in the study, 14 + year old males, had significantly higher serum IgY, pre-albumin and glutathione reductase activity, and the lowest lymphocyte proliferation. This study provided a baseline of immune parameters in captive male Steller's eiders, and the results suggested the parameters were influenced by age-related changes.

Implications of mercury and lead concentrations on breeding physiology and phenology in an Arctic bird

Although physiological traits and phenology are thought to be evolved traits, they often show marked variation within populations, which may be related to extrinsic factors. For example, trace elements such as mercury (Hg) and lead (Pb) alter biochemical processes within wildlife that may affect migration and breeding. While there is a growing understanding of how contaminants may influence wildlife physiology, studies addressing these interactions in free-living species are still limited. We examined how four non-essential trace elements (cadmium, Hg, Pb and selenium) interacted with physiological and breeding measures known to influence breeding in a free-living population of common eider ducks (Somateria mollissima). We collected blood from female eiders as they arrived at a breeding colony in northern Canada. Blood was subsequently assessed for baseline corticosterone (CORT), immunoglobulin Y (IgY), and the four trace elements. We used model selection to identify which elements varied most with CORT, IgY, arrival condition, and arrival timing. We then used path analysis to assess how the top two elements from the model selection process (Hg and Pb) varied with metrics known to influence reproduction. We found that arrival date, blood Hg, CORT, and IgY showed significant inter-annual variation. While blood Pb concentrations were low, blood Pb levels significantly increased with later arrival date of the birds, and varied negatively with eider body condition, suggesting that even at low blood concentrations, Pb may be related to lower investment in reproduction in eiders. In contrast, blood Hg concentrations were positively correlated with eider body condition, indicating that fatter birds also had higher Hg burdens. Overall, our results suggest that although blood Hg and Pb concentrations were below no-effect levels, these low level concentrations of known toxic metals show significant relationships with breeding onset and condition in female eider ducks, factors that could influence reproductive success in this species.