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result(s) for
"Johns, Helen L."
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Challenge of Pigs with Classical Swine Fever Viruses after C-Strain Vaccination Reveals Remarkably Rapid Protection and Insights into Early Immunity
by
Johns, Helen L.
,
Clifford, Derek J.
,
Graham, Simon P.
in
Animal diseases
,
Animal health
,
Animals
2012
Pre-emptive culling is becoming increasingly questioned as a means of controlling animal diseases, including classical swine fever (CSF). This has prompted discussions on the use of emergency vaccination to control future CSF outbreaks in domestic pigs. Despite a long history of safe use in endemic areas, there is a paucity of data on aspects important to emergency strategies, such as how rapidly CSFV vaccines would protect against transmission, and if this protection is equivalent for all viral genotypes, including highly divergent genotype 3 strains. To evaluate these questions, pigs were vaccinated with the Riemser® C-strain vaccine at 1, 3 and 5 days prior to challenge with genotype 2.1 and 3.3 challenge strains. The vaccine provided equivalent protection against clinical disease caused by for the two challenge strains and, as expected, protection was complete at 5 days post-vaccination. Substantial protection was achieved after 3 days, which was sufficient to prevent transmission of the 3.3 strain to animals in direct contact. Even by one day post-vaccination approximately half the animals were partially protected, and were able to control the infection, indicating that a reduction of the infectious potential is achieved very rapidly after vaccination. There was a close temporal correlation between T cell IFN-γ responses and protection. Interestingly, compared to responses of animals challenged 5 days after vaccination, challenge of animals 3 or 1 days post-vaccination resulted in impaired vaccine-induced T cell responses. This, together with the failure to detect a T cell IFN-γ response in unprotected and unvaccinated animals, indicates that virulent CSFV can inhibit the potent antiviral host defences primed by C-strain in the early period post vaccination.
Journal Article
Endocytic tubules regulated by Rab GTPases 5 and 11 are used for envelopment of herpes simplex virus
by
Gonzalez‐Lopez, Claudia
,
Hollinshead, Michael
,
Sayers, Charlotte L
in
Animals
,
Blotting, Western
,
Capsid - metabolism
2012
Enveloped viruses employ diverse and complex strategies for wrapping at cellular membranes, many of which are poorly understood. Here, an ultrastructural study of herpes simplex virus 1 (HSV1)‐infected cells revealed envelopment in tubular membranes. These tubules were labelled by the fluid phase marker horseradish peroxidase (HRP), and were observed to wrap capsids as early as 2 min after HRP addition, indicating that the envelope had recently cycled from the cell surface. Consistent with this, capsids did not colocalise with either the trans‐Golgi network marker TGN46 or late endosomal markers, but showed coincidence with the transferrin receptor. Virus glycoproteins were retrieved from the plasma membrane (PM) to label wrapping capsids, a process that was dependent on both dynamin and Rab5. Combined depletion of Rab5 and Rab11 reduced virus yield to <1%, resulting in aberrant localisation of capsids. These results suggest that endocytosis from the PM into endocytic tubules provides the main source of membrane for HSV1, and reveal a new mechanism for virus exploitation of the endocytic pathway.
HSV capsids are enveloped by tubular membranes of early/recycling endosomal origin under the control of Rab5 and Rab11, rather than membranes derived from the trans‐Golgi network.
Journal Article
CD1− and CD1+ porcine blood dendritic cells are enriched for the orthologues of the two major mammalian conventional subsets
2017
Conventional dendritic cells (cDC) are professional antigen-presenting cells that induce immune activation or tolerance. Two functionally specialised populations, termed cDC1 and cDC2, have been described in humans, mice, ruminants and recently in pigs. Pigs are an important biomedical model species and a key source of animal protein; therefore further understanding of their immune system will help underpin the development of disease prevention strategies. To characterise cDC populations in porcine blood, DC were enriched from PBMC by CD14 depletion and CD172a enrichment then stained with lineage mAbs (Lin; CD3, CD8α, CD14 and CD21) and mAbs specific for CD172a, CD1 and CD4. Two distinct porcine cDC subpopulations were FACSorted CD1
−
cDC (Lin
−
CD172
+
CD1
−
CD4
−
) and CD1
+
cDC (Lin
−
CD172a
+
CD1
+
CD4
−
), and characterised by phenotypic and functional analyses. CD1
+
cDC were distinct from CD1
−
cDC, expressing higher levels of CD172a, MHC class II and CD11b. Following TLR stimulation, CD1
+
cDC produced IL-8 and IL-10 while CD1
−
cDC secreted IFN-α, IL-12 and TNF-α. CD1
−
cDC were superior in stimulating allogeneic T cell responses and in cross-presenting viral antigens to CD8 T cells. Comparison of transcriptional profiles further suggested that the CD1
−
and CD1
+
populations were enriched for the orthologues of cDC1 and cDC2 subsets respectively.
Journal Article
Characterisation of vaccine-induced, broadly cross-reactive IFN-γ secreting T cell responses that correlate with rapid protection against classical swine fever virus
by
Johns, Helen L.
,
Graham, Simon P.
,
Everett, Helen E.
in
Allergy and Immunology
,
Amino Acid Sequence
,
Animals
2012
► Vaccine-induced T cell IFN-γ responses show broad reactivity against CSFV strains. ► T cell epitopes are conserved between CSF and BVD viruses. ► Well conserved antigenic peptides mapped on E2 and NS3 proteins. ► IFN-γ exerts anti-viral effects on CSFV in vitro.
Live attenuated C-strain classical swine fever viruses (CSFV) provide a rapid onset of protection, but the lack of a serological test that can differentiate vaccinated from infected animals limits their application in CSF outbreaks. Since immunity may precede antibody responses, we examined the kinetics and specificity of peripheral blood T cell responses from pigs vaccinated with a C-strain vaccine and challenged after five days with a genotypically divergent CSFV isolate. Vaccinated animals displayed virus-specific IFN-γ responses from day 3 post-challenge, whereas, unvaccinated challenge control animals failed to mount a detectable response. Both CD4+ and cytotoxic CD8+ T cells were identified as the cellular source of IFN-γ. IFN-γ responses showed extensive cross-reactivity when T cells were stimulated with CSFV isolates spanning the major genotypes. To determine the specificity of these responses, T cells were stimulated with recombinant CSFV proteins and a proteome-wide peptide library from a related virus, BVDV. Major cross-reactive peptides were mapped on the E2 and NS3 proteins. Finally, IFN-γ was shown to exert potent antiviral effects on CSFV in vitro. These data support the involvement of broadly cross-reactive T cell IFN-γ responses in the rapid protection conferred by the C-strain vaccine and this information should aid the development of the next generation of CSFV vaccines.
Journal Article
Characterisation of vaccine-induced, broadly cross-reactive IFN-gamma secreting T cell responses that correlate with rapid protection against classical swine fever virus
2012
Highlights * Vaccine-induced T cell IFN-γ responses show broad reactivity against CSFV strains. * T cell epitopes are conserved between CSF and BVD viruses. * Well conserved antigenic peptides mapped on E2 and NS3 proteins. * IFN-γ exerts anti-viral effects on CSFVin vitro.
Journal Article
OVERTURNING IN THE SUBPOLAR NORTH ATLANTIC PROGRAM
by
Zhao, Jian
,
Pickart, Robert S.
,
Lozier, M. Susan
in
Anthropogenic factors
,
Atlantic Meridional Overturning Circulation (AMOC)
,
Atmospheric circulation
2017
For decades oceanographers have understood the Atlantic meridional overturning circulation (AMOC) to be primarily driven by changes in the production of deep-water formation in the subpolar and subarctic North Atlantic. Indeed, current Intergovernmental Panel on Climate Change (IPCC) projections of an AMOC slowdown in the twenty-first century based on climate models are attributed to the inhibition of deep convection in the North Atlantic. However, observational evidence for this linkage has been elusive: there has been no clear demonstration of AMOC variability in response to changes in deep-water formation. The motivation for understanding this linkage is compelling, since the overturning circulation has been shown to sequester heat and anthropogenic carbon in the deep ocean. Furthermore, AMOC variability is expected to impact this sequestration as well as have consequences for regional and global climates through its effect on the poleward transport of warm water. Motivated by the need for a mechanistic understanding of the AMOC, an international community has assembled an observing system, Overturning in the Subpolar North Atlantic Program (OSNAP), to provide a continuous record of the transbasin fluxes of heat, mass, and freshwater, and to link that record to convective activity and water mass transformation at high latitudes. OSNAP, in conjunction with the Rapid Climate Change–Meridional Overturning Circulation and Heatflux Array (RAPID–MOCHA) at 26°N and other observational elements, will provide a comprehensive measure of the three-dimensional AMOC and an understanding of what drives its variability. The OSNAP observing system was fully deployed in the summer of 2014, and the first OSNAP data products are expected in the fall of 2017.
Journal Article
Lagrangian Decomposition of the Atlantic Ocean Heat Transport at 26.5°N
by
Johnson, Helen L.
,
Foukal, Nicholas P.
,
Johns, William E.
in
Atlantic meridional overturning circulation
,
Atlantic Meridional Overturning Circulation (AMOC)
,
Circulation
2024
The Atlantic Meridional Overturning Circulation (AMOC) plays a critical role in the global climate system through the redistribution of heat, freshwater and carbon. At 26.5°N, the meridional heat transport has traditionally been partitioned geometrically into vertical and horizontal circulation cells; however, attributing these components to the AMOC and Subtropical Gyre (STG) flow structures remains widely debated. Using water parcel trajectories evaluated within an eddy‐rich ocean hindcast, we present the first Lagrangian decomposition of the meridional heat transport at 26.5°N. We find that water parcels recirculating within the STG account for 37% (0.36 PW) of the total heat transport across 26.5°N, more than twice that of the classical horizontal gyre component (15%). Our findings indicate that STG heat transport cannot be meaningfully distinguished from that of the basin‐scale overturning since water parcels cooled within the gyre subsequently feed the northward, subsurface limb of the AMOC.
Plain Language Summary
The Atlantic Meridional Overturning Circulation transports heat northward by converting warm, surface waters into cold waters returning at depth. In the subtropical North Atlantic, the heat transported by the overturning circulation has traditionally been separated from the wind‐driven gyre circulation by assuming that the gyre flows horizontally along constant depth levels. By tracing the pathways of virtual water parcels in a high‐resolution ocean model, we show that the heat transported by the subtropical gyre is larger than traditional estimates because water parcels spiral downwards across depth levels. Our results indicate that the subtropical gyre should not be considered separate from the overturning circulation, since the water parcels cooled within the gyre subsequently flow northwards to form cold, dense waters in the subpolar North Atlantic.
Key Points
Water parcels recirculating in the subtropical gyre account for 37% of the total heat transport at 26.5°N in an eddy‐rich ocean hindcast
The heat transport of the subtropical gyre is associated with shallow vertical overturning rather than the horizontal circulation at 26.5°N
Both horizontal and vertical circulation cells are fundamental components of the Atlantic Meridional Overturning Circulation
Journal Article
Seasonal mixed layer depth shapes phytoplankton physiology, viral production, and accumulation in the North Atlantic
2021
Seasonal shifts in phytoplankton accumulation and loss largely follow changes in mixed layer depth, but the impact of mixed layer depth on cell physiology remains unexplored. Here, we investigate the physiological state of phytoplankton populations associated with distinct bloom phases and mixing regimes in the North Atlantic. Stratification and deep mixing alter community physiology and viral production, effectively shaping accumulation rates. Communities in relatively deep, early-spring mixed layers are characterized by low levels of stress and high accumulation rates, while those in the recently shallowed mixed layers in late-spring have high levels of oxidative stress. Prolonged stratification into early autumn manifests in negative accumulation rates, along with pronounced signatures of compromised membranes, death-related protease activity, virus production, nutrient drawdown, and lipid markers indicative of nutrient stress. Positive accumulation renews during mixed layer deepening with transition into winter, concomitant with enhanced nutrient supply and lessened viral pressure.
Phytoplankton are important primary producers. Here the authors investigate phytoplankton physiological changes associated with bloom phases and mixing regimes in the North Atlantic, finding that stratification and deep mixing shape accumulation rates by altering physiology and viral production.
Journal Article
Prevalence and outcomes of breast milk expressing in women with healthy term infants: a systematic review
by
Amir, Lisa H
,
McLachlan, Helen L
,
Johns, Helene M
in
Advertising
,
Body Mass Index
,
Bottle Feeding
2013
Background
Expressing breast milk has become increasingly prevalent, particularly in some developed countries. Concurrently, breast pumps have evolved to be more sophisticated and aesthetically appealing, adapted for domestic use, and have become more readily available. In the past, expressed breast milk feeding was predominantly for those infants who were premature, small or unwell; however it has become increasingly common for healthy term infants. The aim of this paper is to systematically explore the literature related to breast milk expressing by women who have healthy term infants, including the prevalence of breast milk expressing, reported reasons for, methods of, and outcomes related to, expressing.
Methods
Databases (Medline, CINAHL, JSTOR, ProQuest Central, PsycINFO, PubMed and the Cochrane library) were searched using the keywords milk expression, breast milk expression, breast milk pumping, prevalence, outcomes, statistics and data, with no limit on year of publication. Reference lists of identified papers were also examined. A hand-search was conducted at the Australian Breastfeeding Association Lactation Resource Centre. Only English language papers were included. All papers about expressing breast milk for healthy term infants were considered for inclusion, with a focus on the prevalence, methods, reasons for and outcomes of breast milk expression.
Results
A total of twenty two papers were relevant to breast milk expression, but only seven papers reported the prevalence and/or outcomes of expressing amongst mothers of well term infants; all of the identified papers were published between 1999 and 2012. Many were descriptive rather than analytical and some were commentaries which included calls for more research, more dialogue and clearer definitions of breastfeeding. While some studies found an association between expressing and the success and duration of breastfeeding, others found the opposite. In some cases these inconsistencies were compounded by imprecise definitions of breastfeeding and breast milk feeding.
Conclusions
There is limited evidence about the prevalence and outcomes of expressing breast milk amongst mothers of healthy term infants. The practice of expressing breast milk has increased along with the commercial availability of a range of infant feeding equipment. The reasons for expressing have become more complex while the outcomes, when they have been examined, are contradictory.
Journal Article