Emergence of infectious malignant thrombocytopenia in Japanese macaques (Macaca fuscata) by SRV-4 after transmission to a novel host

Pathologic characteristics of infectious diseases in macaque monkeys used in biomedical and toxicologic studies

Nonhuman primates (NHPs), which have many advantages in scientific research and are often the only relevant animals to use in assessing the safety profiles and biological or pharmacological effects of drug candidates, including biologics. In scientific or developmental experiments, the immune systems of animals can be spontaneously compromised possibly due to background infection, experimental procedure-associated stress, poor physical condition, or intended or unintended mechanisms of action of test articles. Under these circumstances, background, incidental, or opportunistic infections can seriously can significantly complicate the interpretation of research results and findings and consequently affect experimental conclusions. Pathologists and toxicologists must understand the clinical manifestations and pathologic features of infectious diseases and the effects of these diseases on animal physiology and experimental results in addition to the spectrum of infectious diseases in healthy NHP colonies. This review provides an overview of the clinical and pathologic characteristics of common viral, bacterial, fungal, and parasitic infectious diseases in NHPs, especially macaque monkeys, as well as methods for definitive diagnosis of these diseases. Opportunistic infections that can occur in the laboratory setting have also been addressed in this review with examples of cases of infection disease manifestation that was observed or influenced during safety assessment studies or under experimental conditions.

[Effect of ethanol on platelet biology]

In recent years, interest in the study of platelets, significantly increased due to recent discoveries providing convincing evidence that their functions by are not limited to their participation in the blood coagulation mechanism. Many works are devoted to the study of the functional state of platelets under conditions of acute and chronic alcohol exposure. The results of such studies can be useful for the development of new markers of the degree of alcohol intoxication of the body for the subsequent choice of the method drug correction of disorders caused by acute or chronic alcohol effects. The review summarizes results in vivo and in vitro of studies performed during more than 60 years on the effect of ethanol on the biogenesis, number, morphology and biochemistry of platelets.

Frequent horizontal and mother-to-child transmission may contribute to high prevalence of STLV-1 infection in Japanese macaques

Background

Simian T-cell leukemia virus type 1 (STLV-1) is disseminated among various non-human primate species and is closely related to human T-cell leukemia virus type 1 (HTLV-1), the causative agent of adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. Notably, the prevalence of STLV-1 infection in Japanese macaques (JMs) is estimated to be > 60%, much greater than that in other non-human primates; however, the mechanism and mode of STLV-1 transmission remain unknown. The aim of this study is to examine the epidemiological background by which STLV-1 infection is highly prevalent in JMs.

Results

The prevalence of STLV-1 in the JMs rearing in our free-range facility reached up to 64% (180/280 JMs) with variation from 55 to 77% among five independent troops. Anti-STLV-1 antibody titers (ABTs) and STLV-1 proviral loads (PVLs) were normally distributed with mean values of 4076 and 0.62%, respectively, which were mostly comparable to those of HTLV-1-infected humans. Our initial hypothesis that some of the macaques might contribute to frequent horizontal STLV-1 transmission as viral super-spreaders was unlikely because of the absence of the macaques exhibiting abnormally high PVLs but poor ABTs. Rather, ABTs and PVLs were statistically correlated (p < 0.0001), indicating that the increasing PVLs led to the greater humoral immune response. Further analyses demonstrated that the STLV-1 prevalence as determined by detection of the proviral DNA was dramatically increased with age; 11%, 31%, and 58% at 0, 1, and 2 years of age, respectively, which was generally consistent with the result of seroprevalence and suggested the frequent incidence of mother-to-child transmission. Moreover, our longitudinal follow-up study indicated that 24 of 28 seronegative JMs during the periods from 2011 to 2012 converted to seropositive (86%) 4 years later; among them, the seroconversion rates of sexually matured (4 years of age and older) macaques and immature macaques (3 years of age and younger) at the beginning of study were comparably high (80% and 89%, respectively), suggesting the frequent incidence of horizontal transmission.

Conclusions

Together with the fact that almost all of the full-adult JMs older than 9 years old were infected with STLV-1, our results of this study demonstrated for the first time that frequent horizontal and mother-to-child transmission may contribute to high prevalence of STLV-1 infection in JMs.

Autophagy Induced by Simian Retrovirus Infection Controls Viral Replication and Apoptosis of Jurkat T Lymphocytes

Autophagy and apoptosis are two important evolutionarily conserved host defense mechanisms against viral invasion and pathogenesis. However, the association between the two pathways during the viral infection of T lymphocytes remains to be elucidated. Simian type D retrovirus (SRV) is an etiological agent of fatal simian acquired immunodeficiency syndrome (SAIDS), which can display disease features that are similar to acquired immunodeficiency syndrome in humans. In this study, we demonstrate that infection with SRV-8, a newly isolated subtype of SRV, triggered both autophagic and apoptotic pathways in Jurkat T lymphocytes. Following infection with SRV-8, the autophagic proteins LC3 and p62/SQSTM1 interacted with procaspase-8, which might be responsible for the activation of the caspase-8/-3 cascade and apoptosis in SRV-8-infected Jurkat cells. Our findings indicate that autophagic responses to SRV infection of T lymphocytes promote the apoptosis of T lymphocytes, which, in turn, might be a potential pathogenetic mechanism for the loss of T lymphocytes during SRV infection.

Infectious Disease Risk Across the Growing Human-Non Human Primate Interface: A Review of the Evidence

Most of the human pandemics reported to date can be classified as zoonoses. Among these, there is a long history of infectious diseases that have spread from non-human primates (NHP) to humans. For millennia, indigenous groups that depend on wildlife for their survival were exposed to the risk of NHP pathogens' transmission through animal hunting and wild meat consumption. Usually, exposure is of no consequence or is limited to mild infections. In rare situations, it can be more severe or even become a real public health concern. Since the emergence of acquired immune deficiency syndrome (AIDS), nobody can ignore that an emerging infectious diseases (EID) might spread from NHP into the human population. In large parts of Central Africa and Asia, wildlife remains the primary source of meat and income for millions of people living in rural areas. However, in the past few decades the risk of exposure to an NHP pathogen has taken on a new dimension. Unprecedented breaking down of natural barriers between NHP and humans has increased exposure to health risks for a much larger population, including people living in urban areas. There are several reasons for this: (i) due to road development and massive destruction of ecosystems for agricultural needs, wildlife and humans come into contact more frequently; (ii) due to ecological awareness, many long distance travelers are in search of wildlife discovery, with a particular fascination for African great apes; (iii) due to the attraction for ancient temples and mystical practices, others travelers visit Asian places colonized by NHP. In each case, there is a risk of pathogen transmission through a bite or another route of infection. Beside the individual risk of contracting a pathogen, there is also the possibility of starting a new pandemic. This article reviews the known cases of NHP pathogens' transmission to humans whether they are hunters, travelers, ecotourists, veterinarians, or scientists working on NHP. Although pathogen transmission is supposed to be a rare outcome, Rabies virus, Herpes B virus, Monkeypox virus, Ebola virus, or Yellow fever virus infections are of greater concern and require quick countermeasures from public health professionals.

Hematological and blood chemistry values in captive Japanese macaques (Macaca fuscata fuscata)

BACKGROUND

Biological information about captive Japanese macaques, including hematology and blood chemistry, is still lacking despite the fact that ethological and ecological data have accumulated during decades of field research.

METHODS

Hematological (511 examinations of 280 Japanese macaques) and blood chemistry data (between 33 and 284 examinations from between 29 and 257 individual macaques) in clinically healthy, simian retrovirus-free Japanese macaques tested between 2009 and 2013 were reviewed.

RESULTS AND CONCLUSIONS

Specific hematological and blood chemistry data for Japanese macaques without clinical signs of disease were provided in this study. Averages presented can be used as hematological parameters for Japanese macaques. Some differences between Japanese macaques and other closely related macaque species were found. Some parameters varied according to macaque age and sex, as well as regional origin. The data in this study will provide useful clinical indices for Japanese macaques in captive and similar conditions.

Experimental infection of Japanese macaques with simian retrovirus 5

Recently, a large number of Japanese macaques (Macaca fuscata) died of an unknown hemorrhagic syndrome at Kyoto University Primate Research Institute (KUPRI) and an external breeding facility for National Institute for Physiological Sciences (NIPS). We previously reported that the hemorrhagic syndrome of Japanese macaques at KUPRI was caused by infection with simian retrovirus 4 (SRV-4); however, the cause of similar diseases that occurred at the external breeding facility for NIPS was still unknown. In this study, we isolated SRV-5 from Japanese macaques exhibiting thrombocytopenia and then constructed an infectious molecular clone of the SRV-5 isolate. When the SRV-5 isolate was inoculated into two Japanese macaques, severe thrombocytopenia was induced in one of two macaques within 22 days after inoculation. Similarly, the clone-derived virus was inoculated into the other two Japanese macaques, and one of two macaques developed severe thrombocytopenia within 22 days. On the other hand, the remaining two of four macaques survived as asymptomatic carriers even after administering an immunosuppressive agent, dexamethasone. As determined by real-time PCR, SRV-5 infected a variety of tissues in Japanese macaques, especially in digestive and lymph organs. We also identified the SRV-5 receptor as ASCT2, a neutral amino acid transporter in Japanese macaques. Taken together, we conclude that the causative agent of hemorrhagic syndrome occurred at the external breeding facility for NIPS was SRV-5.

Hepatocellular carcinoma with intracranial metastasis in a Japanese macaque (Macaca fuscata)

BACKGROUND

A 23-year-old male Japanese macaque (Macaca fuscata) showed left ptosis, which progressed to exophthalmos.

METHODS

The macaque underwent a clinical examination, CT and MRI, and was euthanized. Necropsy and histopathological examination were performed after euthanasia.

RESULTS

The CT revealed and MRI confirmed an intracranial mass at the skull base with orbital extension. At necropsy, there were a large hepatic mass and an intracranial mass compressing the left temporal lobe of the brain. Histopathological and immunohistological examinations revealed that the masses were hepatocellular carcinoma (HCC) and a metastatic lesion. In both the primary and metastatic lesions, neoplastic hepatocytes were arranged mainly in a trabecular pattern. Immunohistochemically, the tumor cells were positive for cytokeratin (AE1/AE3 and CAM5.2) and hepatocyte paraffin 1 and negative for cytokeratin 7 and 20 and vimentin.

CONCLUSION

To our knowledge, this is the first case report of HCC with intracranial metastasis in a macaque.

A novel simian retrovirus subtype discovered in cynomolgus monkeys (Macaca fascicularis)

A new simian retrovirus (SRV) subtype was discovered in China and the USA from Cambodian-origin cynomolgus monkeys. Histopathological examination from necropsied animals showed multifocal lymphoplasmacystic and histocytic inflammation. The complete genome sequences demonstrated that the US virus isolates were nearly identical (99.91-99.93 %) and differed only slightly (99.13-99.16 % identical) from the China isolate. Phylogenetic analysis showed that the new virus isolates formed a distinct branch of SRV-1 through -7, and therefore were named this subtype, SRV-8. This SRV-8 variant was also phylogenetically and serologically more closely related to SRV-4 than any other SRV subtype.

RD-114 virus story: from RNA rumor virus to a useful viral tool for elucidating the world cats' journey

RD-114 virus is a feline endogenous retrovirus (ERV) isolated from human rhabdomyosarcoma in 1971 and classified as endogenous gammaretrovirus in domestic cats (Felis catus). Based on the previous reports in 70's, it has been considered that a horizontal, infectious event occurred to transfer the virus from ancient baboon species to ancient cat species, whereupon it became endogenous in the cat species about several million years ago in Mediterranean Basin. Although it has been believed that all domestic cats harbor infectious RD-114 provirus in their genome, we revealed that cats do not have infectious RD-114 viral loci, but infectious RD-114 virus is resurrected by recombination between uninfectious RD-114 virus-related ERVs [here we designated them as RD-114-related sequences (RDRSs)]. Further, we also revealed the RDRSs which would potentially be resurrected as RD-114 virus (here we refer to them as ''new'' RDRSs) had entered the genome of the domestic cat after domestication of the cat around 10 thousand years ago. The fractions and positions of RDRSs in the cat genome differed in Western and Eastern cat populations and cat breeds. Our study revealed that RDRS would be a useful tool for elucidating the world travel routes of domestic cats after domestication.

Experimental evaluation of the zoonotic infection potency of simian retrovirus type 4 using humanized mouse model

During 2001-2002 and 2008-2011, two epidemic outbreaks of infectious hemorrhagic disease have been found in Japanese macaques (Macaca fuscata) in Kyoto University Primate Research Institute, Japan. Following investigations revealed that the causative agent was simian retrovirus type 4 (SRV-4). SRV-4 was isolated by using human cell lines, which indicates that human cells are potently susceptible to SRV-4 infection. These raise a possibility of zoonotic infection of pathogenic SRV-4 from Japanese macaques into humans. To explore the possibility of zoonotic infection of SRV-4 to humans, here we use a human hematopoietic stem cell-transplanted humanized mouse model. Eight out of the twelve SRV-4-inoculated humanized mice were infected with SRV-4. Importantly, 3 out of the 8 infected mice exhibited anemia and hemophagocytosis, and an infected mouse died. To address the possibility that SRV-4 adapts humanized mouse and acquires higher pathogenicity, the virus was isolated from an infected mice exhibited severe anemia was further inoculated into another 6 humanized mice. However, no infected mice exhibited any illness. Taken together, our findings demonstrate that the zoonotic SRV-4 infection from Japanese macaques to humans is technically possible under experimental condition. However, such zoonotic infection may not occur in the real society.