Evidence of Cross-Reactive Immunity to 2009 Pandemic Influenza A Virus in Workers Seropositive to Swine H1N1 Influenza Viruses Circulating in Italy

Background

Pigs play a key epidemiologic role in the ecology of influenza A viruses (IAVs) emerging from animal hosts and transmitted to humans. Between 2008 and 2010, we investigated the health risk of occupational exposure to swine influenza viruses (SIVs) in Italy, during the emergence and spread of the 2009 H1N1 pandemic (H1N1pdm) virus.

Methodology/Principal Findings

Serum samples from 123 swine workers (SWs) and 379 control subjects (Cs), not exposed to pig herds, were tested by haemagglutination inhibition (HI) assay against selected SIVs belonging to H1N1 (swH1N1), H1N2 (swH1N2) and H3N2 (swH3N2) subtypes circulating in the study area. Potential cross-reactivity between swine and human IAVs was evaluated by testing sera against recent, pandemic and seasonal, human influenza viruses (H1N1 and H3N2 antigenic subtypes). Samples tested against swH1N1 and H1N1pdm viruses were categorized into sera collected before (n. 84 SWs; n. 234 Cs) and after (n. 39 SWs; n. 145 Cs) the pandemic peak. HI-antibody titers ≥10 were considered positive. In both pre-pandemic and post-pandemic peak subperiods, SWs showed significantly higher swH1N1 seroprevalences when compared with Cs (52.4% vs. 4.7% and 59% vs. 9.7%, respectively). Comparable HI results were obtained against H1N1pdm antigen (58.3% vs. 7.7% and 59% vs. 31.7%, respectively). No differences were found between HI seroreactivity detected in SWs and Cs against swH1N2 (33.3% vs. 40.4%) and swH3N2 (51.2 vs. 55.4%) viruses. These findings indicate the occurrence of swH1N1 transmission from pigs to Italian SWs.

Conclusion/Significance

A significant increase of H1N1pdm seroprevalences occurred in the post-pandemic peak subperiod in the Cs (p<0.001) whereas SWs showed no differences between the two subperiods, suggesting a possible occurrence of cross-protective immunity related to previous swH1N1 infections. These data underline the importance of risk assessment and occupational health surveillance activities aimed at early detection and control of SIVs with pandemic potential in humans.     

Evolution of chromosome Y in primates

We have investigated, by fluorescence in situ hybridization (FISH), the cytogenetic evolution of the Y chromosome in primates using 17 yeast artificial chromosomes, representative of the Y-specific euchromatic region of the human chromosome Y. The FISH experiments were performed on great apes (Homo sapiens, Pan troglodytes, Gorilla gorilla and Pongo pygmaeus pygmaeus), and on two Old World monkeys species as an outgroup (Cercopitecidae Macaca fascicularis and Papio anubis). The results showed that this peculiar chromosome has undergone rapid and unconstrained evolution both in sequence content and organization. Received: 16 January 1998; in revised form: 29 May 1998 / Accepted: 24 June 1998     

Population Structure of Barley Landrace Populations and Gene-Flow with Modern Varieties

Landraces are heterogeneous plant varieties that are reproduced by farmers as populations that are subject to both artificial and natural selection. Landraces are distinguished by farmers due to their specific traits, and different farmers often grow different populations of the same landrace. We used simple sequence repeats (SSRs) to analyse 12 barley landrace populations from Sardinia from two collections spanning 10 years. We analysed the population structure, and compared the population diversity of the landraces that were collected at field level (population). We used a representative pool of barley varieties for diversity comparisons and to analyse the effects of gene flow from modern varieties. We found that the Sardinian landraces are a distinct gene pool from those of both two-row and six-row barley varieties. There is also a low, but significant, mean level and population-dependent level of introgression from the modern varieties into the Sardinian landraces. Moreover, we show that the Sardinian landraces have the same level of gene diversity as the representative sample of modern commercial varieties grown in Italy in the last decades, even within population level. Thus, these populations represent crucial sources of germplasm that will be useful for crop improvement and for population genomics studies and association mapping, to identify genes, loci and genome regions responsible for adaptive variations. Our data also suggest that landraces are a source of valuable germplasm for sustainable agriculture in the context of future climate change, and that in-situ conservation strategies based on farmer use can preserve the genetic identity of landraces while allowing adaptation to local environments.     

A conserved folding mechanism for PDZ domains

An important question in protein folding is whether the folding mechanism is sequence dependent and conserved for homologous proteins. In this work we compared the kinetic folding mechanism of five postsynaptic density protein-95, disc-large tumor suppressor protein, zonula occludens-1 (PDZ) domains, sharing similar topology but having different primary structures. Investigation of the different proteins under various experimental conditions revealed that the folding kinetics of each member of the PDZ family can be described by a model with two transition states separated by an intermediate. Moreover, the positions of the two transition states along the reaction coordinate (as given by their beta(T)-values) are fairly constant for the five PDZ domains.     

Relaxation kinetics following sudden Ca(2+) reduction in single myofibrils from skeletal muscle

To investigate the roles of cross-bridge dissociation and cross-bridge-induced thin filament activation in the time course of muscle relaxation, we initiated force relaxation in single myofibrils from skeletal muscles by rapidly (approximately 10 ms) switching from high to low [Ca(2+)] solutions. Full force decay from maximal activation occurs in two phases: a slow one followed by a rapid one. The latter is initiated by sarcomere "give" and dominated by inter-sarcomere dynamics (see the companion paper, Stehle, R., M. Krueger, and G. Pfitzer. 2002. Biophys. J. 83:2152-2161), while the former occurs under nearly isometric conditions and is sensitive to mechanical perturbations. Decreasing the Ca(2+)-activated force preceding the start of relaxation does not increase the rate of the slow isometric phase, suggesting that cycling force-generating cross-bridges do not significantly sustain activation during relaxation. This conclusion is strengthened by the finding that the rate of isometric relaxation from maximum force to any given Ca(2+)-activated force level is similar to that of Ca(2+)-activation from rest to that given force. It is likely, therefore, that the slow rate of force decay in full relaxation simply reflects the rate at which cross-bridges leave force-generating states. Because increasing [P(i)] accelerates relaxation while increasing [MgADP] slows relaxation, both forward and backward transitions of cross-bridges from force-generating to non-force-generating states contribute to muscle relaxation.     

Animal xenodiversity in Italian inland waters: distribution, modes of arrival, and pathways

The paper provides a list of the non-indigenous animal species occurring today in Italian inland waters. Xenodiversity was found to amount to 112 species (64 invertebrates and 48 vertebrates), which contribute for about 2% to the inland-water fauna in Italy. Northern and central regions are most affected, and Asia, North America, and the rest of Europe are the main donor continents. The large majority of non-indigenous species entered Italy as a direct or indirect effect of human intervention. A difference between invertebrates and vertebrates was found for their mode of arrival (unintentional for invertebrates and intentional for vertebrates). Accidental transport, in association with both fish (for aquaculture or stock enhancement) and crops, has been the main vector of invertebrate introductions, whereas vertebrates were mostly released for stocking purposes. Overall stock enhancement (47.92%) and culture (37.5%) prevailed over the other pathways. Seventeen and 7 species of our list are included among the 100 worst invasive species of Europe (DAISIE) and of the world (IUCN), respectively. For some (but not all) non-indigenous species recorded in Italy the multilevel impact exerted on the recipient communities and ecosystems is known, even if rarely quantified, but knowledge on their chronic impact is still missing. Additional research is needed to provide criteria for prioritizing intervention against well established invaders and identify which new potential invader should be targeted as “unwanted”.     

Plant inner membrane anion channel (PIMAC) function in plant mitochondria

To date, the existence of the plant inner membrane anion channel (PIMAC) has been shown only in potato mitochondria, but its physiological role remains unclear. In this study, by means of swelling experiments in K(+) and ammonium salts, we characterize a PIMAC-like anion-conducting pathway in mitochondria from durum wheat (DWM), a monocotyledonous species phylogenetically far from potato. DWM were investigated since they possess a very active potassium channel (PmitoK(ATP)), so implying a very active matching anion uniport pathway and, possibly, a coordinated function. As in potato mitochondria, the electrophoretic uptake of chloride and succinate was inhibited by matrix [H(+)], propranolol, and tributyltin, and was insensitive to Mg(2+), N,N'-dicyclohexylcarbodiimide (DCCD) and mercurials, thus showing PIMAC's existence in DWM. PIMAC actively transports dicarboxylates, oxodicarboxylates, tricarboxylates and Pi. Interestingly, a novel mechanism of swelling in ammonium salts of isolated plant mitochondria is reported, based on electrophoretic anion uptake via PIMAC and ammonium uniport via PmitoK(ATP). PIMAC is inhibited by physiological compounds, such as ATP and free fatty acids, by high electrical membrane potential (Delta Psi), but not by acyl-CoAs or reactive oxygen species. PIMAC was found to cooperate with dicarboxylate carrier by allowing succinate uptake that triggers succinate/malate exchange in isolated DWM. Similar results were obtained using mitochondria from the dicotyledonous species topinambur, so suggesting generalization of results. We propose that PIMAC is normally inactive in vivo due to ATP and Delta Psi inhibition, but activation may occur in mitochondria de-energized by PmitoK(ATP) (or other dissipative systems) to replace or integrate the operation of classical anion carriers.