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Gibbons are often difficult to observe in dense forest habitats using traditional ground-based methods. This makes it challenging to estimate group sizes and, in turn, population sizes. This has proven to be a key constraint on accurate monitoring of the last remaining population of the Critically Endangered cao vit gibbon Nomascus nasutus. However, new technologies are beginning to circumvent the problems associated with traditional methods. We hypothesized that, by using an unoccupied aerial vehicle (UAV) equipped with thermal and standard (RGB) cameras, we could obtain more accurate group size counts than by using ground-based observations, as fewer gibbons would be missed. We tested this during a population survey of the cao vit gibbon, finding that the thermal video footage revealed additional individuals that were not counted by ground-based surveyors. Statistically, there was strong evidence (93% probability) that UAV-derived counts were higher (by 41%) than concurrent ground-based counts. We recorded six primate groups of three species (cao vit gibbon, rhesus macaque Macaca mulatta and Assamese macaque Macaca assamensis), including 24 gibbons across four groups (c. 20% of the global population). The RGB video footage also revealed seven female gibbons, two of which were carrying infants, providing vital group composition data. These data have contributed directly to a more accurate population survey of the species than would have been possible using direct observation only. We anticipate more widespread use of UAVs in the study of gibbons and other threatened species, leading to a more robust evidence base for their conservation.

The cao vit gibbon ( Nomascus nasutus ) is one of the rarest primates on Earth and now only survives in a single forest patch of less than 5000 ha on the Vietnam–China border. Accurate monitoring of the last remaining population is critical to inform ongoing conservation interventions and track conservation success over time. However, traditional methods for monitoring gibbons, involving triangulation of groups from their songs, are inherently subjective and likely subject to considerable measurement errors. To overcome this, we aimed to use ‘vocal fingerprinting’ to distinguish the different singing males in the population. During the 2021 population survey, we complemented the traditional observations made by survey teams with a concurrent passive acoustic monitoring array. Counts of gibbon group sizes were also assisted with a UAV-mounted thermal camera. After identifying eight family groups in the acoustic data and incorporating long-term data, we estimate that the population was comprised of 74 individuals in 11 family groups, which is 38% smaller than previously thought. We have no evidence that the population has declined—indeed it appears to be growing, with new groups having formed in recent years—and the difference is instead due to double-counting of groups in previous surveys employing the triangulation method. Indeed, using spatially explicit capture-recapture modelling, we uncovered substantial measurement error in the bearings and distances from field teams. We also applied semi- and fully-automatic approaches to clustering the male calls into groups, finding no evidence that we had missed any males with the manual approach. Given the very small size of the population, conservation actions are now even more urgent, in particular habitat restoration to allow the population to expand. Our new population estimate now serves as a more robust basis for informing management actions and tracking conservation success over time.

Trachypithecus, which currently contains 20 species divided into four groups, is the most speciose and geographically dispersed genus among Asian colobines. Despite several morphological and molecular studies, however, its evolutionary history and phylogeography remain poorly understood. Phayre's langur (Trachypithecus phayrei) is one of the most widespread members of the genus, but details on its actual distribution and intraspecific taxonomy are limited and controversial. Thus, to elucidate the evolutionary history of Trachypithecus and to clarify the intraspecific taxonomy and distribution of T. phayrei, we sequenced 41 mitochondrial genomes from georeferenced fecal samples and museum specimens, including two holotypes. Phylogenetic analyses revealed a robustly supported phylogeny of Trachypithecus, suggesting that the T. pileatus group branched first, followed by the T. francoisi group, and the T. cristatus and T. obscurus groups most recently. The four species groups diverged from each other 4.5-3.1 million years ago (Ma), while speciation events within these groups occurred much more recently (1.6-0.3 Ma). Within T. phayrei, we found three clades that diverged 1.0-0.9 Ma, indicating the existence of three rather than two taxa. Following the phylogenetic species concept and based on genetic, morphological, and ecological differences, we elevate the T. phayrei subspecies to species level, describe a new species from central Myanmar, and refine the distribution of the three taxa. Overall, our study highlights the importance of museum specimens and provides new insights not only into the evolutionary history of T. phayrei but the entire Trachypithecus genus as well.

The Tonkin snub-nosed monkey ( Rhinopithecus avunculus ) with a global population of <250 is listed as critically endangered. It is endemic to northeastern Vietnam and was feared extinct until its rediscovery in 1989. The largest single population of R. avunculus consists of 125–130 individuals in an area of forest called Khau Ca in Ha Giang Province. We used non-invasively collected fecal samples to establish the amount of genetic diversity in this population based on mitochondrial information. We amplified and sequenced a 467- to 650-bp section of the hypervariable region I (HVI) of the mitochondrial D-loop for 201 samples and reconstructed the full mitochondrial genomes for five samples based on metagenomic data. All 201 HVI sequences were identical and no variability was found in the five mitochondrial genomes. Our results highlight the immediate need for a comprehensive assessment of the genetic diversity of all populations of R. avunculus based on mitochondrial and nuclear markers. The latter need to be developed for this species.

Studies of the positional behavior of wild primates are important for understanding relationships between ecology, behavior and morphology. The aim of this study was to examine the effects of body size, dimorphism, ontogeny and seasonal changes on positional behavior and support use of the Tonkin snub-nosed monkey (Rhinopithecus avunculus). From January 2009 to December 2010, I collected videography-based data on the positional behavior and support use via bout sampling method of R. avunculus in Khau Ca Forest, Ha Giang Province, Vietnam. I also studied the forest structure and phenology of the habitats of R. avunculus in Khau Ca Forest. Using G-tests (Row x Column statistical comparisons), I tested for significant differences in postural and locomotor profiles for associated maintenance activities, sex- and age-based differences, and seasonal changes for the Tonkin snub-nosed monkeys. First, I documented the positional repertoire of adult male R. avunculus to include nine locomotor modes (19 submodes) and six postural modes (16 submodes). Quadrupedalism was the most frequent locomotion, followed by leap, climb, drop, arm-swing, and other locomotion. Sitting was the most frequent posture, followed by stand, lie, cling and other postures. Second, I tested sex-based differences in positional behavior and support use of R. avunculus. The results showed that there were differences between adult males and females in positional behavior and support use, but these differences did not consistently follow the predictions based on body size. Third, I found there were significant age-based differences in positional behavior and support use of R. avunculus during maintenance activities. Larger-bodied adults climbed more frequently, and leapt less frequently than smaller-bodied juveniles and infants during travel. The frequency of sitting increased with age while resting and feeding. Larger-bodied adults tended to use larger supports and more flexible supports than smaller-bodied juveniles and infants. Finally, the data indicated that there were significant differences between dry/cold and wet/warm seasons in positional behavior and support use of R. avunculus. Seasonal changes in positional behavior and support use of R. avunculus might be associated with the shift of diet, foraging/feeding behavior, and ambient temperatures by seasons.

Introduction Chronic obstructive pulmonary disease (COPD) is the third leading cause of death worldwide. COPD results from chronic inflammation of the lungs. Current treatments, including physical and chemical therapies, provide limited results. Stem cells, particularly mesenchymal stem cells (MSCs), are used to treat COPD. Here, we evaluated the safety and efficacy of umbilical cord-derived (UC)-MSCs for treating COPD. Methods Twenty patients were enrolled, 9 at stage C and 11 at stage D per the Global Initiative for Obstructive Lung Disease (GOLD) classification. Patients were infused with 10 6 cells/kg of expanded allogeneic UC-MSCs. All patients were followed for 6 months after the first infusion. The treatment end-point included a comprehensive safety evaluation, pulmonary function testing (PFT), and quality-of-life indicators including questionnaires, the 6-min walk test (6MWT), and systemic inflammation assessments. All patients completed the full infusion and 6-month follow-up. Results No infusion-related toxicities, deaths, or severe adverse events occurred that were deemed related to UC-MSC administration. The UC-MSC-transplanted patients showed a significantly reduced Modified Medical Research Council score, COPD assessment test, and number of exacerbations. However, the forced expiratory volume in 1 s, C-reactive protein, and 6MWT values were nonsignificantly reduced after treatment (1, 3, and 6 months) compared with those before the treatment. Conclusion Systemic UC-MSC administration appears to be safe in patients with moderate-to-severe COPD, can significantly improve their quality of life, and provides a basis for subsequent cell therapy investigations. Trial registration ISRCTN, ISRCTN70443938 . Registered 06 July 2019

This study was performed to investigate the prevalence and to characterize the genetic diversity of Histomonas meleagridis isolates in chickens in southern Vietnam. A total of 194 chickens, randomly selected from 18 backyard and 18 commercial flocks, were screened for H. meleagridis infection using both macroscopic diagnosis and an 18S rRNA gene-based PCR method. Overall, 12.9% of birds, representing 19 flocks, showed gross lesions typical for histomonosis whereas 25.3% of the birds from 29 flocks were positive by PCR assay. Following initial diagnostic approaches, H. meleagridis-positive samples were further analyzed by sequencing three different genomic loci; the 18S rRNA, alpha-actinin1, and rpb1. Thirteen samples from 12 flocks were genetically identified as H. meleagridis, demonstrating a flock and sample prevalence of 33.3% and 6.7%, respectively. There was no significant difference in prevalence between different farm types, age groups, and seasonality. Genetic analysis demonstrated minor heterogeneity of Vietnamese isolates with 99% homology to H. meleagridis sequences from the database. This is the first survey of the prevalence and genetic characterization of H. meleagridis in chickens in Vietnam.

Background The human major histocompatibility complex class I polypeptide-related sequence B (MICB) is a protein that modulates the NK and T cell activation through the NKG2D receptor and is related to several diseases including cancer. Methods The study investigated the prognostic role of soluble MICB (sMICB) protein in the progression of HBV-related liver diseases and to HBV-related HCC treatment. The sMICB serum levels were measured in 266 chronic HBV-infected Vietnamese patients and in healthy controls, and correlated with clinical and laboratory parameters and with therapeutic interventions for HBV-related HCC. Results Significant differences in both clinical and laboratory parameters were observed among the patient groups with different stages of hepatitis. The platelet counts were significantly decreased with disease progression ( P  < 0.001). The sMICB serum levels were significantly increased in HBV patients compared to healthy controls ( P  < 0.0001). Among the patients with different stages of hepatitis, asymptomatic individuals (ASYM) revealed higher sMICB serum levels while liver cirrhosis (LC) patients revealed lower sMICB serum levels ( P  < 0.0001) compared to other patient groups. Notably, the sMICB serum levels were decreased in treated HCC patient group compared to not-treated HCC patient group ( P  = 0.05). Additionally, the sMICB levels were significantly correlated with platelet counts in ASYM and HCC patients (r = −0.37, P  = 0.009; and r = 0.22, P  = 0.025, respectively). Conclusions Our results demonstrate a potential role of sMICB serum levels and platelet counts during immune response to the HBV infection, liver disease progression and response to the HCC treatment.