Immunological Mechanisms Mediating Hantavirus Persistence in Rodent Reservoirs

Hantaviruses, similar to several emerging zoonotic viruses, persistently infect their natural reservoir hosts, without causing overt signs of disease. Spillover to incidental human hosts results in morbidity and mortality mediated by excessive proinflammatory and cellular immune responses. The mechanisms mediating the persistence of hantaviruses and the absence of clinical symptoms in rodent reservoirs are only starting to be uncovered. Recent studies indicate that during hantavirus infection, proinflammatory and antiviral responses are reduced and regulatory responses are elevated at sites of increased virus replication in rodents. The recent discovery of structural and non-structural proteins that suppress type I interferon responses in humans suggests that immune responses in rodent hosts could be mediated directly by the virus. Alternatively, several host factors, including sex steroids, glucocorticoids, and genetic factors, are reported to alter host susceptibility and may contribute to persistence of hantaviruses in rodents. Humans and reservoir hosts differ in infection outcomes and in immune responses to hantavirus infection; thus, understanding the mechanisms mediating viral persistence and the absence of disease in rodents may provide insight into the prevention and treatment of disease in humans. Consideration of the coevolutionary mechanisms mediating hantaviral persistence and rodent host survival is providing insight into the mechanisms by which zoonotic viruses have remained in the environment for millions of years and continue to be transmitted to humans.Hantaviruses are negative sense, enveloped RNA viruses (family: Bunyaviridae) that are comprised of three RNA segments, designated small (S), medium (M), and large (L), which encode the viral nucleocapsid (N), envelope glycoproteins (G_N and G_C), and an RNA polymerase (Pol), respectively. More than 50 hantaviruses have been found worldwide [1]. Each hantavirus appears to have coevolved with a specific rodent or insectivore host as similar phylogenetic trees are produced from virus and host mitochondrial gene sequences [2]. Spillover to humans causes hemorrhagic fever with renal syndrome (HFRS) or hantavirus cardiopulmonary syndrome (HCPS), depending on the virus [3]–[5]. Although symptoms vary, a common feature of both HFRS and HCPS is increased permeability of the vasculature and mononuclear infiltration [4]. Pathogenesis of HRFS and HCPS in humans is hypothesized to be mediated by excessive proinflammatory and CD8+ T cell responses (​).

Table 1

Summary of Immune Responses in Humans during Hantavirus Infection.

Review of horses in Paleoindian sites of the Americas

Analysis of the morphological characters in North and South American horses present during Paleoindian time indicates that at least eight Equus ecospecies occurred in North America. In South America, Equus had radiated into four ecospecies, Hippidion had one, and Onohippidium had three geographically separate ecospecies. These species are found in archeological deposits ranging from ca. 13,000 to 8,000 yr B.P., in tropical habitats as well as in the high Andean and Patagonian colder ecotopes.     

Structure of Desert Rodent Communities: A Critical Review of Questions and Approaches

Three attributes of communities—the number, relative abundances,and phenotypic attributes of coexisting species—togetherdefine their "structure," as the term has been used in the literature.Most ecologists have tried to uncover determinants of communitystructure by analyzing patterns of morphology or resource use,or by experimentally manipulating the species composition orenvironmental context of communities. Less often used is a mechanisticanalysis of processes operating at the level of individualsor populations. I discuss the logical basis for each of these approaches andillustrate their virtues and limitations with examples drawnfrom work on heteromyid rodents. While pattern analytic andexperimental approaches have provided an efficient means ofidentifying proximate determinants of species number and relativeabundance, a mechanistic approach holds more promise for answeringquestions about the ultimate determinants of phenotypic patternswithin communities     

A private allele ubiquitous in the Americas

The three-wave migration hypothesis of Greenberg et al. has permeated the genetic literature on the peopling of the Americas. Greenberg et al. proposed that Na-Dene, Aleut-Eskimo and Amerind are language phyla which represent separate migrations from Asia to the Americas. We show that a unique allele at autosomal microsatellite locus D9S1120 is present in all sampled North and South American populations, including the Na-Dene and Aleut-Eskimo, and in related Western Beringian groups, at an average frequency of 31.7%. This allele was not observed in any sampled putative Asian source populations or in other worldwide populations. Neither selection nor admixture explains the distribution of this regionally specific marker. The simplest explanation for the ubiquity of this allele across the Americas is that the same founding population contributed a large fraction of ancestry to all modern Native American populations.     

A History of Dogs in the Early Americas

. History of Dogs in the Early Americas. Marion Schwartz. New Haven, CT: Yale University Press, 1997. 233 pp.     

Chiefdoms and Chieftaincy in the Americas

Chiefdoms and Chieftaincy in the Americas. Elsa M. Redmond. ed. Gainesville: University Press of Florida, 1998. 303 pp.     

Beneficial Effects of Caloric Restriction on Chronic Kidney Disease in Rodent Models: A Meta-Analysis and Systematic Review

Background

Numerous studies have demonstrated the life-extending effect of caloric restriction. It is generally accepted that caloric restriction has health benefits, such as prolonging lifespan and delaying the onset and progression of CKD in various species, especially in rodent models. Although many studies have tested the efficacy of caloric restriction, no complete quantitative analysis of the potential beneficial effects of reducing caloric intake on the development and progression of CKD has been published.

Methods

All studies regarding the relationship between caloric restriction and chronic kidney diseases were searched in electronic databases, including PubMed/MEDLINE, EMBASE, Science Citation Index (SCI), OVID evidence-based medicine, Chinese Bio-medical Literature and Chinese science and technology periodicals (CNKI, VIP, and Wan Fang). The pooled odds ratios (OR) and 95% confidence intervals (95% CI) were calculated by using fixed- or random-effects models.

Results

The data from 27 of all the studies mentioned above was used in the Meta analysis. Through the meta-analysis, we found that the parameter of blood urea nitrogen, serum creatinine and urinary protein levels of the AL group was significant higher than that of the CR group, which are 4.11 mg/dl, 0.08mg/dl and 33.20mg/kg/24h, respectively. The incidence of the nephropathy in the caloric restriction (CR) group was significantly lower than that in the ad libitum—fed (AL) group. We further introduced the subgroup analysis and found that the effect of caloric restriction on the occurrence of kidney disease was only significant with prolonged intervention; the beneficial effects of CR on the 60%-caloric-restriction group were greater than on the less-than-60%-caloric-restriction group, and caloric restriction did not show obvious protective effects in genetically modified strains. Moreover, survival rate of the caloric restriction group is much higher than that of the ad libitum—fed (AL) group.

Conclusions

Our findings demonstrate for the first time that compared with the AL group, the caloric restriction indeed decreased urea nitrogen, creatinine, urine protein, incidence of kidney diseases and increased the survival rate on 700~800 days.     

Coconuts in the Americas

It has been clearly established that the Portuguese introduced coconuts to the Cape Verde islands in 1499, and these supplied the Atlantic coasts and the Caribbean in the 1500s. By contrast, early 16th century reports of coconuts on the Pacific coast of Panama are controversial. Recent DNA analysis of modern coconut populations there shows them to be similar to Philippine varieties, agreeing with morphometric analysis. Hence, coconuts must have been brought by boat from the western Pacific, but no archaeological, ethnobotanical or linguistic evidence for pre-Columbian coconuts has been found. Thus, the most parsimonious explanation is that coconuts were introduced to Panama after Spanish conquest, as supported by DNA analysis and historical records of Spanish voyages. New collections along the Pacific coast, from Mexico to Colombia, are increasing the sampling for genetic analysis, and further work in the Philippines is suggested to test probable origins. Unless new archaeological discoveries prove otherwise, the strong hypothesis of Philippine origin should direct future research on the sources of American Pacific coast coconuts.     

Ecological and Control Techniques for Sand Flies (Diptera: Psychodidae) Associated with Rodent Reservoirs of Leishmaniasis

Background

Leishmaniasis remains a global health problem because of the substantial holes that remain in our understanding of sand fly ecology and the failure of traditional vector control methods. The specific larval food source is unknown for all but a few sand fly species, and this is particularly true for the vectors of Leishmania parasites. We provide methods and materials that could be used to understand, and ultimately break, the transmission cycle of zoonotic cutaneous leishmaniasis.

Methods and Findings

We demonstrated in laboratory studies that analysis of the stable carbon and nitrogen isotopes found naturally in plant and animal tissues was highly effective for linking adult sand flies with their larval diet, without having to locate or capture the sand fly larvae themselves. In a field trial, we also demonstrated using this technique that half of captured adult sand flies had fed as larvae on rodent feces. Through the identification of rodent feces as a sand fly larval habitat, we now know that rodent baits containing insecticides that have been shown in previous studies to pass into the rodents'' feces and kill sand fly larvae also could play a future role in sand fly control. In a second study we showed that rubidium incorporated into rodent baits could be used to demonstrate the level of bloodfeeding by sand flies on baited rodents, and that the elimination of sand flies that feed on rodents can be achieved using baits containing an insecticide that circulates in the blood of baited rodents.

Conclusions

Combined, the techniques described could help to identify larval food sources of other important vectors of the protozoa that cause visceral or dermal leishmaniasis. Unveiling aspects of the life cycles of sand flies that could be targeted with insecticides would guide future sand fly control programs for prevention of leishmaniasis.     

Hantavirus infection and biodiversity in the Americas

Oecologia - Species diversity has been proposed to decrease prevalence of disease in a wide variety of host–pathogen systems, in a phenomenon labeled the dilution effect. This phenomenon was...     

Craniometric variation in the Americas

Craniofacial variation is investigated in Latin America and the Caribbean. The samples included in this study are two historic and one prehistoric sample from Ecuador; prehistoric and modern Cuban samples; a prehistoric Peruvian sample; two prehistoric Mexican samples and one contemporary admixed Mexican sample; a 16th/17th-century Spanish sample; and Terry blacks. Biological distance is investigated using traditional craniometrics by computing size and shape variables according to Mosimann and colleagues. This study shows that there is much biological variation within the Americas.     

A Plan to Coordinate the Culture of the Three Americas

Music education has always required advocacy to solidify its place in the school curriculum. Music teachers are increasingly called on to justify their existence and importance in the schools, and yet, are often unprepared to advocate on their own behalf without the use of advocacy materials that are created on the basis of questionable research, questionable interpretations of valid research, or materials that demean the profession. This practical advocacy crisis is created by the lack of a solid philosophical basis for music education advocacy, the profusion of questionable advocacy materials available, and the lack of lobbying at the federal and state levels for meaningful laws that give arts education true core status. In the article, the author discusses suggestions for improving advocacy methods and materials.