Primates and primatologists: social contexts for interspecies pathogen transmission

Humans and nonhuman primates (NHP) interact in a variety of contexts. The frequency, duration, and intensity of interspecies interaction influence the likelihood that contact results in cross-species transmission of infectious agents. In this study, we present results of a cross-sectional survey of attendees at a national conference of primatologists, characterizing their occupational exposures to NHP. Of 116 individuals who participated in the study, 68.1% reported having worked with NHP in a field setting, 68.1% in a laboratory setting, and 24.1% at a zoo or animal sanctuary. Most subjects (N=98, 84.5%) reported having worked with multiple NHP taxa, including 46 (39.7%) who had worked with more than five distinct taxa. Sixty-nine subjects (59.5%) recalled having been scratched by a NHP and 48 (41.1%) had been bitten; 32 subjects reporting being bitten more than once. Eleven subjects (9.5%) reported having been injured by a needle containing NHP tissue or body fluids. We conclude that primatologists are at high risk for exposure to NHP-borne infectious agents. Furthermore, primatologists' varied occupational activities often bring them into contact with multiple NHP species in diverse contexts and geographic areas, over extended periods of time, making them a unique population with respect to zoonotic and anthropozoonotic disease risk.     

Modelling pathogen transmission: the interrelationship between local and global approaches

We describe two spatial (cellular automaton) host-pathogen models with contrasting types of transmission, where the biologically realistic transmission mechanisms are based entirely on 'local' interactions. The two models, fixed contact area (FCA) and fixed contact number (FCN), may be viewed as local 'equivalents' of commonly used global density- (and frequency-) dependent models. Their outputs are compared with each other and with the patterns generated by these global terms. In the FCN model, unoccupied cells are bypassed, but in the FCA model these impede pathogen spread, extending the period of the epidemic and reducing the prevalence of infection when the pathogen persists. Crucially, generalized linear modelling reveals that the global transmission terms betaSI and beta'SI/N are equally good at describing transmission in both the FCA and FCN models when infected individuals are homogeneously distributed and N is approximately constant, as at the quasi-equilibrium. However, when N varies, the global frequency-dependent term beta'SI/N is better than the density-dependent one, betaSI, at describing transmission in both the FCA and FCN models. Our approach may be used more generally to compare different local contact structures and select the most appropriate global transmission term.     

Assessing variation in the social behavior of stumptail macaques using thermal criteria

This paper reports a method for comparing the environments of nonhuman primates based on biophysical, thermal criteria. The method is applied to an analysis of behaviors exhibited by group-living stumptail macaques (Macaca arctoides), documented by a group-scan observation technique, to test the hypothesis that the expression of social behavior is dependent on thermal conditions. Thermal conditions are identified by considering sky cover and the relative cooling power of the environment. The results show that the rates of occurrence of affiliative, play, and solitary behaviors are altered significantly at a relative cooling power at or above 550 kcal/m2/hr under cloudy conditions and at or above 600 kcal/m2/hr under sunny conditions. In addition, the rates of occurrence of play, sexual, aggressive, and submissive behavioral states are also significantly different under cloudy, rather than sunny, conditions over particular ranges of cooling. It is possible to conclude that thermal criteria affect the expression of social behaviors by stumptail macaques. This is consistent with studies of huddling behavior exhibited by stumptail macaques and rhesus macaques (M. mulatta), and suggests that 1) certain changes in the expression of social behaviors may be thermoregulatory in at least some nonhuman primate species and 2) thermal criteria are likely to be useful tools when conducting comparative analyses of behavioral data collected on animals in outdoor environments.     

The MHC E locus in macaques is polymorphic and is conserved between macaques and humans

Although the functions of the molecules encoded by the classical MHC class I loci are well defined, no function has been ascribed to the molecules encoded by the non-classical MHC class I loci. To investigate the evolution and conservation of the non-classical loci, we cloned and sequenced HLA-E homologues in macaques. We isolated four E locus alleles from five rhesus monkeys and two E locus alleles from one cynomolgus monkey, which indicated that the E locus in macaques is polymorphic. We also compared the rate of nucleotide substitution in the second intron of the macaque and human E locus alleles with that of exons two and three. The rate of nucleotide substitution was significantly higher in the introns, which suggested that the E locus has evolved under selective pressure. Additionally, comparison of the rates of synonymous and non-synonymous substitutions in the peptide binding region versus the remainder of the molecule suggested that the codons encoding the amino acids in the peptide binding region had been conserved in macaques and humans over the 36 million years since macaques and humans last shared a common ancestor.The nucleotide sequence data reported in this paper have been submitted to the GenBank nucleotide sequence database and have been assigned the accession numbers UO2976–UO2981     

Assessing the spontaneous cage behavior of the squirrel monkey (Saimiri sciureus)

A Behavioral Activity Index for rapid assessment of spontaneous cage behavior of the squirrel monkey is described. Observing the behavior of six male squirrel monkeys, it was found that four readily identifiable behaviors accounted for 62% of the total activity during a 30 minutes observation period. The need for a technique to reliably assess changes in baseline behavior is discussed in relation to behavioral pharmacological investigations.This research was supported by a Grant from the Moody Foundation, Galveston, Texas, and by the Physiological Psychology Branch, Office of Naval Research, Contract 1598-06.     

Shoe soles as a potential vector for pathogen transmission: a systematic review

Shoe soles are possible vectors for infectious diseases. Although studies have been performed to assess the prevalence of infectious pathogens on shoe soles and decontamination techniques, no systematic review has ever occurred. The aim of this study was to perform a systematic review of the literature to determine the prevalence of infectious agents on shoe bottoms and possible decontamination strategies. Three electronic bibliographic databases were searched using a predefined search strategy evaluating prevalence of infectious pathogens on shoe bottoms and decontamination strategies. Quality assessment was performed independently by two reviews with disagreements resolved by consensus. Thirteen studies were identified that supported the hypothesis that shoe soles are a vector for infectious pathogens. Methicillin‐resistant Staphylococcus aureus, Clostridium difficile and multidrug‐resistant Gram‐negative species among other pathogens were documented on shoe bottoms in the health care setting, in the community and among food workers. Fifteen studies were identified that investigated decontamination strategies for shoe soles. A number of decontamination strategies have been studied of which none have been shown to be consistently successful at disinfecting shoe soles. In conclusion, a high prevalence of microbiological pathogens was identified from shoe soles studied in the health care, community and animal worker setting. An effective decontamination strategy for shoe soles was not identified. Studies are needed to assess the potential for contaminated shoes to contribute to the transmission of infectious pathogens.     

Conserved MHC class I peptide binding motif between humans and rhesus macaques

Since the onset of the HIV pandemic, the use of nonhuman primate models of infection has increasingly become important. An excellent model to study HIV infection and immunological responses, in particular cell-mediated immune responses, is SIV infection of rhesus macaques. CTL epitopes have been mapped using SIV-infected rhesus macaques, but, to date, a peptide binding motif has been described for only one rhesus class I MHC molecule, Mamu-A*01. Herein, we have established peptide-live cell binding assays for four rhesus MHC class I molecules: Mamu-A*11, -B*03, -B*04, and -B*17. Using such assays, peptide binding motifs have been established for all four of these rhesus MHC class I molecules. With respect to the nature and spacing of crucial anchor positions, the motifs defined for Mamu-B*04 and -B*17 present unique features not previously observed for other primate species. The motifs identified for Mamu-A*11 and -B*03 are very similar to the peptide binding motifs previously described for human HLA-B*44 and -B*27, respectively. Accordingly, naturally processed peptides derived from HLA-B*44 and HLA-B*27 specifically bind Mamu-A*11 and Mamu-B*03, respectively, indicating that conserved MHC class I binding capabilities exist between rhesus macaques and humans. The definition of four rhesus MHC class I-specific motifs expands our ability to accurately detect and quantitate immune responses to MHC class I-restricted epitopes in rhesus macaques and to rationally design peptide epitope-based model vaccine constructs destined for use in nonhuman primates.     

Trade-off between virulence and vertical transmission and the maintenance of a virulent plant pathogen

The continuum hypothesis predicts that parasites should evolve reduced virulence if they have higher opportunity for vertical transmission. However, when there is a trade-off between virulence and vertical transmission, selection may favor horizontal transmission and higher virulence. Atkinsonella hypoxylon is a fungal pathogen that reduces Danthonia fitness by 50% or more when it completely castrates hosts' chasmogamous inflorescences, despite the high opportunity for vertical transmission through cleistogamous seeds. Sporadically, infected hosts with partially castrated inflorescences (which have higher fecundity than completely castrated hosts) are observed in natural populations. Why are partially castrated plants rare if selection favors reduced virulence? We investigated whether there was genetic diversity for virulence among A. hypoxylon genotypes and the relationship between virulence and vertical transmission. We found that the fungal genotype significantly affects the occurrence of partial castration in Danthonia compressa. The proportion of seedlings that were vertically infected by their maternal plant was lower for partially castrated than for completely castrated plants. Our results demonstrate a trade-off between virulence and vertical transmission, explaining the maintenance of more virulent, completely castrating fungal genotypes in natural populations, and suggest that vertical transmission in plants is more complex than what is considered in current models.     

Risk assessment: A model for predicting cross-species transmission of simian foamy virus from macaques (M. fascicularis) to humans at a monkey temple in Bali, Indonesia

Contact between humans and nonhuman primates (NHPs) frequently occurs at monkey temples (religious sites that have become associated with free-ranging populations of NHPs) in Asia, creating the potential for NHP-human disease transmission. In March 2003 a multidisciplinary panel of experts participated in a workshop designed to model the risk of NHP-human pathogen transmission. The panel developed a risk assessment model to describe the likelihood of cross-species transmission of simian foamy virus (SFV) from temple macaques (Macaca fascicularis) to visitors at monkey temples. SFV is an enzootic simian retrovirus that has been shown to be transmitted from NHPs to humans. In operationalizing the model field data, laboratory data and expert opinions were used to estimate the likelihood of SFV transmission within this context. This model sets the stage for a discussion about modeling as a risk assessment tool and the kinds of data that are required to accurately predict transmission.     

Relationship between culture redox potential and culture fluorescence inCorynebacterium glutamicum

Summary Transient experiments were performed during a batch fermentation ofCorynebacterium glutamicum ATCC 14296 in which the flow of air to the reactor was cut off. The fluorescence of the culture was observed to vary linearly with the culture redox potential during the transient. This observation was made below the sensitivity limit of a dissolved oxygen probe. It appears that redox potential in conjunction with fluorescence measurements are of utility in studying extra- and intracellular reduction states, particularly in the microaerobic regime.     

Plasmodium knowlesi: reservoir hosts and tracking the emergence in humans and macaques

Plasmodium knowlesi, a malaria parasite originally thought to be restricted to macaques in Southeast Asia, has recently been recognized as a significant cause of human malaria. Unlike the benign and morphologically similar P. malariae, these parasites can lead to fatal infections. Malaria parasites, including P. knowlesi, have not yet been detected in macaques of the Kapit Division of Malaysian Borneo, where the majority of human knowlesi malaria cases have been reported. In order to extend our understanding of the epidemiology and evolutionary history of P. knowlesi, we examined 108 wild macaques for malaria parasites and sequenced the circumsporozoite protein (csp) gene and mitochondrial (mt) DNA of P. knowlesi isolates derived from macaques and humans. We detected five species of Plasmodium (P. knowlesi, P. inui, P. cynomolgi, P. fieldi and P. coatneyi) in the long-tailed and pig-tailed macaques, and an extremely high prevalence of P. inui and P. knowlesi. Macaques had a higher number of P. knowlesi genotypes per infection than humans, and some diverse alleles of the P. knowlesi csp gene and certain mtDNA haplotypes were shared between both hosts. Analyses of DNA sequence data indicate that there are no mtDNA lineages associated exclusively with either host. Furthermore, our analyses of the mtDNA data reveal that P. knowlesi is derived from an ancestral parasite population that existed prior to human settlement in Southeast Asia, and underwent significant population expansion approximately 30,000-40,000 years ago. Our results indicate that human infections with P. knowlesi are not newly emergent in Southeast Asia and that knowlesi malaria is primarily a zoonosis with wild macaques as the reservoir hosts. However, ongoing ecological changes resulting from deforestation, with an associated increase in the human population, could enable this pathogenic species of Plasmodium to switch to humans as the preferred host.     

昆虫介体行为与植物病毒的传播

大多数植物病毒都是依赖昆虫介体进行传播,其中超过80%的传毒介体昆虫都是属于半翅目同翅亚目。昆虫介体识别寄主植物和取食的过程与病毒的传播密切相关,本文主要综述了同翅亚目昆虫、蓟马等介体昆虫取食行为与植物病毒的相互作用方面的研究进展,着重于介绍昆虫不同取食阶段的行为对植物病毒传播的影响,病毒侵染对介体取食和识别寄主行为的影响。     

The oldest anatomically modern humans from far southeast Europe: direct dating, culture and behavior

Background

Anatomically Modern Humans (AMHs) are known to have spread across Europe during the period coinciding with the Middle to Upper Paleolithic transition. Whereas their dispersal into Western Europe is relatively well established, evidence of an early settlement of Eastern Europe by modern humans are comparatively scarce.

Methodology/Principal Finding

Based on a multidisciplinary approach for the study of human and faunal remains, we describe here the oldest AMH remains from the extreme southeast Europe, in conjunction with their associated cultural and paleoecological background. We applied taxonomy, paleoecology, and taphonomy combined with geomorphology, stratigraphy, archeology and radiocarbon dating. More than 160 human bone remains have been discovered. They originate from a well documented Upper Paleolithic archeological layer (Gravettian cultural tradition) from the site of Buran-Kaya III located in Crimea (Ukraine). The combination of non-metric dental traits and the morphology of the occipital bones allow us to attribute the human remains to Anatomically Modern Humans. A set of human and faunal remains from this layer has been radiocarbon dated by Accelerator Mass Spectrometry. The direct-dating results of human bone establish a secure presence of AMHs at 31,900+240/−220 BP in this region. They are the oldest direct evidence of the presence of AMHs in a well documented archeological context. Based on taphonomical observations (cut marks and distribution of skeletal elements), they represent the oldest Upper Paleolithic modern humans from Eastern Europe, showing post-mortem treatment of the dead as well.

Conclusion/Significance

These findings are essential for the debate on the spread of modern humans in Europe during the Upper Paleolithic, as well as their cultural behaviors.     

Disrupting the transmission of a vector-borne plant pathogen

Approaches to control vector-borne diseases rarely focus on the interface between vector and microbial pathogen, but strategies aimed at disrupting the interactions required for transmission may lead to reductions in disease spread. We tested if the vector transmission of the plant-pathogenic bacterium Xylella fastidiosa was affected by three groups of molecules: lectins, carbohydrates, and antibodies. Although not comprehensively characterized, it is known that X. fastidiosa adhesins bind to carbohydrates, and that these interactions are important for initial cell attachment to vectors, which is required for bacterial transmission from host to host. Lectins with affinity to substrates expected to occur on the cuticular surface of vectors colonized by X. fastidiosa, such as wheat germ agglutinin, resulted in statistically significant reductions in transmission rate, as did carbohydrates with N-acetylglucosamine residues. Presumably, lectins bound to receptors on the vector required for cell adhesion/colonization, while carbohydrate-saturated adhesins on X. fastidiosa's cell surface. Furthermore, antibodies against X. fastidiosa whole cells, gum, and afimbrial adhesins also resulted in transmission blockage. However, no treatment resulted in the complete abolishment of transmission, suggesting that this is a complex biological process. This work illustrates the potential to block the transmission of vector-borne pathogens without directly affecting either organism.     

Linking community and disease ecology: the impact of biodiversity on pathogen transmission

The increasing number of zoonotic diseases spilling over from a range of wild animal species represents a particular concern for public health, especially in light of the current dramatic trend of biodiversity loss. To understand the ecology of these multi-host pathogens and their response to environmental degradation and species extinctions, it is necessary to develop a theoretical framework that takes into account realistic community assemblages. Here, we present a multi-host species epidemiological model that includes empirically determined patterns of diversity and composition derived from community ecology studies. We use this framework to study the interaction between wildlife diversity and directly transmitted pathogen dynamics. First, we demonstrate that variability in community composition does not affect significantly the intensity of pathogen transmission. We also show that the consequences of community diversity can differentially impact the prevalence of pathogens and the number of infectious individuals. Finally, we show that ecological interactions among host species have a weaker influence on pathogen circulation than inter-species transmission rates. We conclude that integration of a community perspective to study wildlife pathogens is crucial, especially in the context of understanding and predicting infectious disease emergence events.     

Cryptococcus gattii: an emerging fungal pathogen infecting humans and animals

Infectious fungi are among a broad group of microbial pathogens that has and continues to emerge concomitantly due to the global AIDS pandemic as well as an overall increase of patients with compromised immune systems. In addition, many pathogens have been emerging and re-emerging, causing disease in both individuals who have an identifiable immune defect and those who do not. The fungal pathogen Cryptococcus gattii can infect individuals with and without an identifiable immune defect, with a broad geographic range including both endemic areas and emerging outbreak regions. Infections in patients and animals can be severe and often fatal if untreated. We review the molecular epidemiology, population structure, clinical manifestations, and ecological niche of this emerging pathogen.