Simian adenoviruses: Molecular and serological survey in monkeys and humans in Thailand

Understanding zoonotic pathogens and risk factors from wildlife in Southeast Asia: a systematic literature review

The COVID-19 pandemic has demonstrated the significance of the human-animal interface in the emergence of zoonotic diseases, with wildlife serving as an important source of infection. A better understanding of the specific pathogens and mechanisms involved is vital to prepare against future outbreaks, especially in Southeast Asia, a hotspot for zoonotic diseases. This paper reviews the published literature on wildlife zoonoses in this region from 2012 to 2022. The results show a diverse range of potential zoonotic pathogens and the widespread occurrence of zoonotic diseases from wildlife. Drivers of zoonotic pathogen spillover include (i) environmental factors (e.g. animal habitat disruption, environmental conditions, exposure to contaminated water/food/soil), (ii) animal factors (e.g. movement patterns, age-related susceptibility), (iii) human factors (e.g. lack of awareness, poor hygiene practices, age, gender and income) and (iv) human-animal-environmental interface factors (e.g. close contact between humans and animals, exposure through visiting animals and presence of vectors). The diverse drivers of zoonoses in Southeast Asia put its communities at risk for infection. To mitigate these risks, global health efforts should consider adopting a One Health approach to foster collaboration across human, animal, and wildlife health sectors. This could involve educating communities on safe animal interactions and improving disease surveillance.

Potential Zoonotic Infections Transmitted by Free-Ranging Macaques in Human-Monkey Conflict Areas in Thailand

INTRODUCTION

Nonhuman primates (NHPs) can transmit zoonotic diseases to humans because of their close genetic relationship, facilitating the cross-species transmission of certain pathogens. In Thailand, Macaca is the most common NHP genus and their inhabits area are in close proximity of human, particularly in urban and suburban areas, where frequent interactions with humans increase the risk of pathogen transmission. The risk is influenced by factors such as the type of pathogen, the mode of transmission (e.g. direct contact or vector-borne), and the density of human and macaque populations in the regions. This study aims to investigate potential zoonotic infections in free-ranging macaques residing in human-monkey conflict areas.

METHODS

From 2014 to 2023, 2703 macaques across 29 provinces in Thailand were tested for 18 pathogens using PCR, RT-PCR, or real-time PCR. The associations between disease occurrence, demographic variables, and sample types of macaques were analysed using univariable and multivariable regression.

RESULTS

The overall pathogen infection percentage was 35.7% (965/2703). Simian foamy virus (SFV) had the highest infection percentage at 52.5% (759/1446), followed by Herpesviridae at 41.4% (353/852), Plasmodium spp. at 1.8% (14/758), and hepatitis B virus at 0.1% (2/1403). Significant differences were observed among different sampling sites, macaque age groups, and species in infection proportion of SFV, and Herpesviridae.

CONCLUSIONS

Identifying the pathogens carried by macaques is crucial for preparing for potential disease epidemics and outbreaks.

Novel Mastadenovirus Infection as Cause of Pneumonia in Imported Black-and-White Colobuses (Colobus guereza), Thailand

We identified a novel mastadenovirus, herein referred to as colobus adenovirus (CoAdV), as the likely cause of fatal respiratory and enteric diseases in multiple black-and-white colobuses (Colobus guereza) imported into Thailand in 2022. Among 9 affected colobuses, 4 died. Viral antigen was abundant in respiratory and enteric tissues, where prominent lesions and clinical signs were observed. We successfully cultivated CoAdV in Vero cells and characterized the complete viral genome, which indicated the virus is genetically distinct from other simian adenoviruses. We also conducted a retrospective study of archival samples from 7 other unrelated colobuses that had respiratory distress or diarrhea and found similar viral strains in 4 of those colobuses. Although we could not determine the potential harm to humans or other nonhuman primates from current information, the zoonotic and spillover potential of this virus to other related hosts should not be neglected. Veterinarians should consider CoAdV when pneumonia is diagnosed in colobuses.

The Validation of Whole β-Globin Gene Sequencing for Detecting β-Thalassemia Mutations Found in Thailand Using Next-Generation Sequencing (NGS)

Beta-thalassemia is an inherited disorder prevalent in Thailand and Southeast Asia. Several molecular techniques for identifying β-thalassemia mutations have been reported. Next-generation sequencing (NGS) is a type of effective molecular testing with high throughput and accuracy. Hence, this study aims to evaluate a novel barcode-tagged NGS approach based on a short-read assay. A total of 258 samples with 54 different β-thalassemia genotypes related to 32 mutations were gathered and evaluated. A library was constructed with the BTSeqTM kit and sequencing was performed on the Illumina NGS machine. The validation results showed 98.45% concordance with conventional genotypes. Less discordant results (1.55%) were limited to insertional mutations and included one case of each of the following: HBB:c.27dupG, HBB:c.85dupC, HBB:c.216dupT, and HBB:c.440_441dupAC. Five single-nucleotide polymorphisms that derived from the NGS results were also analyzed in terms of allele frequency and revealed significant differences between the wild types and other β-genotypes. Furthermore, this paper is the first to describe rare single-nucleotide polymorphisms including IVS II-109 (C/T), IVS II-258 (G/A), IVS II-613 (T-C), and IVS II-806 (G/C). Interestingly, the C allele of IVS II-806 was found to have 100% linkage with two cases of Hb Tak. The haplotype and phylogenetic analysis was also constructed based on variants and revealed three clusters in the Hb variants, which represented their evolution and genetic background. Finally, NGS with the barcode-tagged method has a high throughput, which is suitable for large population screening. Its cost effectiveness and less complicated process promote its application in further works.

A Novel Mastadenovirus from Nyctalus noctula Which Represents a Distinct Evolutionary Branch of Viruses from Bats in Europe

Bats are natural hosts of a wide variety of viruses, including adenoviruses. European bats are known to carry mastadenoviruses categorized as species B (widespread in European Vespertilionidae bats) and whose taxonomy has not been clarified. We examined fecal samples from Vespertilionidae bats (five species) captured in central Russia and found that 2/12 (16%) were positive for mastadenoviruses. The partial genome of the mastadenovirus was assembled from Pipistrellus nathusii, representing the bat adenovirus species B. The complete genome (37,915 nt) of a novel mastadenovirus was assembled from Nyctalus noctula and named BatAdV/MOW15-Nn19/Quixote. Comparative studies showed significant divergence of the Quixote genome sequence from European bat mastadenoviruses, while the only known virus showing low similarity was the isolate WA3301 from an Australian bat, and together they formed a subclade that separated from other BatAdVs. Phylogenetic and comparative analysis of the protein-coding genes provided evidence that Quixote is related to a novel species within the genus Mastadenovirus, provisionally named "K" (as the next available letter for the species). Phylogenetic analyses revealed that some earlier viruses from Western European bats, for which only partial DNA polymerase genes are known, are most likely members of the tentatively named species "K". Thus, at least two species of mastadenovirus are circulating in bats throughout Europe, from western to eastern areas.

Vaccine adjuvants for infectious disease in the clinic

Adjuvants, materials added to vaccines to enhance the resulting immune response, are important components of vaccination that are many times overlooked. While vaccines always include an antigen to tell the body what to vaccinate to, of equal importance the adjuvant provides the how, a significant factor in producing a complete response. The adjuvant space has been slow to develop with the first use of an adjuvant in a licensed vaccine occurring in the 1930s, and remaining the only adjuvant in licensed vaccines for the next 80 years. However, with vaccination at the forefront of protection against new and complex pathogens, it is important to consider all components when designing an effective vaccine. Here we summarize the adjuvant space in licensed vaccines as well as the novel adjuvant space in clinical trials with a specific focus on the materials utilized and their resulting impact on the immune response. We discuss five major categories of adjuvant materials: aluminum salts, nanoparticles, viral vectors, TLR agonists, and emulsions. For each category, we delve into the current clinical trials space, the impact of these materials on vaccination, as well as some of the ways in which they could be improved. Adjuvants present an exciting opportunity to improve vaccine responses and stability, this review will help inform about the current progress of this space.

Translational impact statement

In the aftermath of the COVID-19 pandemic, vaccines for infectious diseases have come into the spotlight. While antigens have always been an important focus of vaccine design, the adjuvant is a significant tool for enhancing the immune response to the vaccine that has been largely underdeveloped. This article provides a broad review of the history of adjuvants and, the current vaccine adjuvant space, and the progress seen in adjuvants in clinical trials. There is specific emphasis on the material landscape for adjuvants and their resulting mechanism of action. Looking ahead, while the novel vaccine adjuvant space features exciting new technologies and materials, there is still a need for more to meet the protective needs of new and complex pathogens.

Isolation of a recombinant simian adenovirus encoding the human adenovirus G52 hexon suggests a simian origin for human adenovirus G52

Human adenoviruses (HAdVs) are causative agents of morbidity and mortality throughout the world. These double-stranded DNA viruses are phylogenetically classified into seven different species (A-G). HAdV-G52, originally isolated in 2008 from a patient presenting with gastroenteritis, is the sole human-derived member of species G. Phylogenetic analysis previously suggested that HAdV-G52 may have a simian origin, indicating a potential zoonotic spillover into humans. However, evidence of HAdV-G52 in either human or simian populations has not been reported since. Here, we describe the isolation and in vitro characterization of rhesus (rh)AdV-69, a novel simian AdV with clear evidence of recombination with HAdV-G52, from the stool of a rhesus macaque. Specifically, the rhAdV-69 hexon capsid protein is 100% identical to that of HAdV-G52, whereas the remainder of the genome is most similar to rhAdV-55, sharing 95.36% nucleic acid identity. A second recombination event with an unknown adenovirus (AdV) is evident at the short fiber gene. From the same sample, we also isolated a second, highly related recombinant AdV (rhAdV-68) that harbors a distinct hexon gene but nearly identical backbone compared to rhAdV-69. In vitro, rhAdV-68 and rhAdV-69 demonstrate comparable growth kinetics and tropisms in human cell lines, nonhuman cell lines, and human enteroids. Furthermore, we show that coinfection of highly related AdVs is not unique to this sample since we also isolated coinfecting rhAdVs from two additional rhesus macaque stool samples. Our data collectively contribute to elucidating the origins of HAdV-G52 and provide insights into the frequency of coinfections and subsequent recombination in AdV evolution.IMPORTANCEUnderstanding the host origins of adenoviruses (AdVs) is critical for public health as transmission of viruses from animals to humans can lead to emergent viruses. Recombination between animal and human AdVs can also produce emergent viruses. HAdV-G52 is the only human-derived member of the HAdV G species. It has been suggested that HAdV-G52 has a simian origin. Here, we isolated from a rhesus macaque, a novel rhAdV, rhAdV-69, that encodes a hexon protein that is 100% identical to that of HAdV-G52. This observation suggests that HAdV-G52 may indeed have a simian origin. We also isolated a highly related rhAdV, differing only in the hexon gene, from the same rhesus macaque stool sample as rhAdV-69, illustrating the potential for co-infection of closely related AdVs and recombination at the hexon gene. Furthermore, our study highlights the critical role of whole-genome sequencing in understanding AdV evolution and monitoring the emergence of pathogenic AdVs.

Evolving Horizons: Adenovirus Vectors' Timeless Influence on Cancer, Gene Therapy and Vaccines

Efficient and targeted delivery of a DNA payload is vital for developing safe gene therapy. Owing to the recent success of commercial oncolytic vector and multiple COVID-19 vaccines, adenovirus vectors are back in the spotlight. Adenovirus vectors can be used in gene therapy by altering the wild-type virus and making it replication-defective; specific viral genes can be removed and replaced with a segment that holds a therapeutic gene, and this vector can be used as delivery vehicle for tissue specific gene delivery. Modified conditionally replicative-oncolytic adenoviruses target tumors exclusively and have been studied in clinical trials extensively. This comprehensive review seeks to offer a summary of adenovirus vectors, exploring their characteristics, genetic enhancements, and diverse applications in clinical and preclinical settings. A significant emphasis is placed on their crucial role in advancing cancer therapy and the latest breakthroughs in vaccine clinical trials for various diseases. Additionally, we tackle current challenges and future avenues for optimizing adenovirus vectors, promising to open new frontiers in the fields of cell and gene therapies.

Markers of antroponotic viral infections in vervet monkeys arrived from their natural habitat (Tanzania)

INTRODUCTION

Various human viruses have been identified in wild monkeys and in captive primates. Cases of transmission of viruses from wild monkeys to humans and vice versa are known. The aim of this study was to identify markers of anthroponotic viral infections in vervet monkeys (Chlorocebus pygerythrus) arrived from their natural habitat (Tanzania).

MATERIALS AND METHODS

Fecal samples (n = 56) and blood serum samples (n = 75) obtained from 75 animals, respectively, on days 10 and 23 after admission to the primate center, were tested for the markers of anthroponotic viral infections (Ebola virus, Marburg virus, lymphocytic choriomeningitis, hepatitis C virus, herpes simplex virus (HSV), cytomegalovirus (CMV), Epstein-Barr virus (EBV), parainfluenza types 1 and 3, intestinal adenoviruses, rotaviruses) by enzyme immunoassay (ELISA) and polymerase chain reaction (PCR).

RESULTS AND DISCUSSION

Among the examined animals, markers of 6 out of 11 tested viral infections were identified. Detection rates of IgG antibodies to HSV-1,2 (15.9%) and CMV (15.9%) were two times as low as IgG antibodies to EBV (31.8%). Among the markers of respiratory viral infections, IgG antibodies to parainfluenza virus type 1 were found (6.8%). 14.3% of the animals had rotavirus antigen, and 94% had simian adenovirus DNA. Markers of hemorrhagic fevers Ebola, Marburg, LCM, hepatitis C, and type 3 parainfluenza were not detected.

CONCLUSION

When importing monkeys from different regions of the world, an expanded screening for viral infections is needed considering the epidemiological situation both in the country of importation and in the country of destination.

Isolation of novel simian adenoviruses from macaques for development of a vector for human gene therapy and vaccines

IMPORTANCE

Adenoviruses are widely used in gene therapy and vaccine delivery. Due to the high prevalence of human adenoviruses (HAdVs), the pre-existing immunity against HAdVs in humans is common, which limits the wide and repetitive use of HAdV vectors. In contrast, the pre-existing immunity against simian adenoviruses (SAdVs) is low in humans. Therefore, we performed epidemiological investigations of SAdVs in simians and found that the SAdV prevalence was as high as 33.9%. The whole-genome sequencing and sequence analysis showed SAdV diversity and possible cross species transmission. One isolate with low level of pre-existing neutralizing antibodies in humans was used to construct replication-deficient SAdV vectors with E4orf6 substitution and E1/E3 deletion. Interestingly, we found that the E3 region plays a critical role in its replication in human cells, but the absence of this region could be compensated for by the E4orf6 from HAdV-5 and the E1 expression intrinsic to HEK293 cells.

Non-invasive specimen collections for Mycobacterium tuberculosis detection in free-ranging long-tailed macaques (Macaca fascicularis)

Surveillance of infectious diseases in free-ranging or wild animals has been widely conducted in many habitat-range countries after the COVID-19 episode. Thailand is located in the center of the distribution range of long-tailed macaques (Macaca fascicularis; Mf) where the animals have both frequent human contact and a high prevalence of human tuberculosis. For the large-scale detection of Mycobacterium tuberculosis complex (MTBC) using IS6110-nested PCR in free-ranging Mf, non-invasive sampling was developed using oral (via rope bait) and fecal (direct swabs of fresh feces) specimen collection. Firstly, the MTBC-IS6110-nested PCR was validated in non-invasively collected specimens, in terms of its specificity and sensitivity, and then compared with those of the invasively collected oral and rectal swabs in 24 captive MTBC-suspected Mf. After validation, these methods were applied to survey for the prevalence of shed MTBC (MTBCS) in four previously reported MTBC-infected populations. A total of 173 baited rope specimens and 204 freshly defecated excretions were collected. The limit of detection of the IS6110-nested PCR technique was 10 fg/μL and the 181-bp PCR amplicon showed 100% sequence similarity with the MTB H37Rv genome sequence. Comparing the MTBCS detection between the invasive and non-invasive collected specimens in captive suspected Mf revealed a significant correlation between the two types of oral specimens (oral swabs and baited ropes; n = 24, r2 = 1, p-value < 0.001), but fresh fecal swabs showed higher MTBCS frequencies than the rectal swabs. Moreover, the proportion of MTBCS-positive free-ranging Mf were significantly higher in the fresh fecal swabs (8.82%; 95% CI; 4.9-12.7%) than in the baited ropes (5.20%; 95% CI; 1.9-8.5%). This result indicates that oral sampling via baited ropes and fecal sampling via defecated excretion swabs can serve as ancillary specimens for MTBCS detection in free-ranging non-human primates.

Detection and Molecular Characterization of Adenoviruses in Captive and Free-Roaming African Green Monkeys (Chlorocebus sabaeus): Evidence for Possible Recombination and Cross-Species Transmission

In the present study, 31 samples (12 fecal, 9 nasal and 10 rectal swabs) from 28/92 (30.43%, 10 captive and 18 free-roaming African green monkeys (AGMs, Chlorocebus sabaeus)) apparently healthy AGMs in the Caribbean Island of St. Kitts tested positive for adenoviruses (AdVs) by DNA-dependent DNA polymerase (pol)-, or hexon-based screening PCR assays. Based on analysis of partial deduced amino acid sequences of Pol- and hexon- of nine AGM AdVs, at least two AdV genetic variants (group-I: seven AdVs with a Simian mastadenovirus-F (SAdV-F)/SAdV-18-like Pol and hexon, and group-II: two AdVs with a SAdV-F/SAdV-18-like Pol and a Human mastadenovirus-F (HAdV-F)/HAdV-40-like hexon) were identified, which was corroborated by analysis of the nearly complete putative Pol, complete hexon, and partial penton base sequences of a representative group-I (strain KNA-08975), and -II (KNA-S6) AdV. SAdV-F-like AdVs were reported for the first time in free-roaming non-human primates (NHPs) and after ~six decades from captive NHPs. Molecular characterization of KNA-S6 (and the other group-II AdV) indicated possible recombination and cross-species transmission events involving SAdV-F-like and HAdV-F-like viruses, corroborating the hypothesis that the evolutionary pathways of HAdVs and SAdVs are intermingled, complicated by recombination and inter-species transmission events, especially between related AdV species, such as HAdV-F and SAdV-F. To our knowledge, this is the first report on detection and molecular characterization of AdVs in AGMs.

A Novel Simian Adenovirus Associating with Human Adeno-virus Species G Isolated from Long-Tailed Macaque Feces

Metagenomics has demonstrated its capability in outbreak investigations and pathogen surveillance and discovery. With high-throughput and effective bioinformatics, many disease-causing agents, as well as novel viruses of humans and animals, have been identified using metagenomic analysis. In this study, a VIDISCA metagenomics workflow was used to identify potential unknown viruses in 33 fecal samples from asymptomatic long-tailed macaques (Macaca fascicularis) in Ratchaburi Province, Thailand. Putatively novel astroviruses, enteroviruses, and adenoviruses were detected and confirmed by PCR analysis of long-tailed macaque fecal samples collected from areas in four provinces, Ratchaburi, Kanchanaburi, Lopburi, and Prachuap Khiri Khan, where humans and monkeys live in proximity (total n = 187). Astroviruses, enteroviruses, and adenoviruses were present in 3.2%, 7.5%, and 4.8% of macaque fecal samples, respectively. One adenovirus, named AdV-RBR-6-3, was successfully isolated in human cell culture. Whole-genome analysis suggested that it is a new member of the species Human adenovirus G, closely related to Rhesus adenovirus 53, with evidence of genetic recombination and variation in the hexon, fiber, and CR1 genes. Sero-surveillance showed neutralizing antibodies against AdV-RBR-6-3 in 2.9% and 11.2% of monkeys and humans, respectively, suggesting cross-species infection of monkeys and humans. Overall, we reported the use of metagenomics to screen for possible new viruses, as well as the isolation and molecular and serological characterization of the new adenovirus with cross-species transmission potential. The findings emphasize that zoonotic surveillance is important and should be continued, especially in areas where humans and animals interact, to predict and prevent the threat of emerging zoonotic pathogens.