Molecular and Phylogenetic Characterization of Novel Papillomaviruses Isolated from Oral and Anogenital Neoplasms of Japanese Macaques (Macaca fuscata).

Papillomaviruses (PVs) are a diverse group of host species-specific DNA viruses, etiologically linked with various benign and malignant neoplasms of cutaneous and mucosal epithelia. Here, we describe the detection and characterization of the first two PVs naturally infecting Japanese macaques (Macaca fuscata), including the determination of their etiological association(s) with the development of original neoplasms. The molecular and phylogenetic analyses were performed on complete genome sequences of Macaca fuscata PV types 1 (MfuPV1) and 2 (MfuPV2), which were completely sequenced in samples of a malignant oral tumor and benign anogenital neoplasm of Japanese macaques, respectively. Subsequently, two type-specific quantitative real-time PCRs were developed to estimate viral loads of MfuPV1 and MfuPV2 and to evaluate their etiological roles. The in silico molecular analyses revealed that both viral genomes encode characteristic PV proteins with conserved functional domains and have a non-coding genomic region with regulatory sequences to regulate and complete the viral life cycle. However, additional experimental evidence is needed to finally confirm the presence and biological functionality of the molecular features of both novel PVs. While MfuPV1, together with PVs identified in other macaques, is classified into the Alphapapillomavirus (Alpha-PV) species 12, MfuPV2 is most likely a representative of the novel viral species within the Alpha-PV genus. Their relatively high viral loads suggest that both PVs are etiologically linked with the development of the original neoplasms.

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.

Persistent Infection of Simian Foamy Virus Derived from the Japanese Macaque Leads to the High-Level Expression of microRNA that Resembles the miR-1 microRNA Precursor Family.

MicroRNAs (miRNAs) are a group of small non-coding RNAs that suppress the expression of target mRNAs. The seed sequence of miRNA plays a crucial role in recognizing the 3'-untranslated region of the target mRNA. Cells infected with a simian foamy virus (SFV) isolated from an African green monkey (Chlorocebus aethiops) (SFVcae) showed high expression levels of viral miRNAs encoded in the long terminal repeat of SFVcae. In the present study, we investigated the roles and expression of miRNAs derived from an SFV isolated from a Japanese macaque (Macaca fuscata) (SFVmfu) using next-generation sequencing technologies. The results obtained showed that SFVmfu also expressed viral miRNAs; however, the seed sequences of most miRNAs derived from SFVmfu differed from those reported previously from SFVcae. Cells persistently infected with SFVmfu strongly expressed an miRNA with the same seed sequence as the miR-1 microRNA precursor family. Luciferase reporter assays indicated that this miRNA down-regulates the expression of adenylyl cyclase-associated protein 1, which is up-regulated in several solid tumors. The present results suggest that SFVmfu utilizes viral miRNAs to establish long-term co-existence with the Japanese macaque.

Phylogenetic analyses reveal that simian foamy virus isolated from Japanese Yakushima macaques (Macaca fuscata yakui) is distinct from most of Japanese Hondo macaques (Macaca fuscata fuscata).

Japanese macaque (Macaca fuscata) is an indigenous Old World monkey (OWM) species that inhabits the Japanese archipelago. There are two subspecies of Japanese macaque: Yakushima macaque (M. f. yakui) which inhabits Yakushima Island exclusively, and Hondo macaque (M. f. fuscata) which inhabits the mainland of Japan. Yakushima macaque is considered to be branched off from a certain parental macaque group that had inhabited the mainland of Japan. However, the process of sub-speciation of the Yakushima macaque is still unclear at present. In this study, to gain new insight into the process of sub-speciation of Japanese macaque, we utilized the simian foamy virus (SFV) as a marker. SFVs are found in virtually all primates except humans and undergo species-specific cospeciation with the hosts. The phylogenetic analysis of conserved regions of the env gene in SFVs remarkably resembled that of the OWMs with high statistical confidence. The phylogenetic analyses also indicated that there are four (1-4) genotypes among Asian OWMs investigated. SFVs derived from Asian OWMs except Yakushima macaque were classified as genotypes 1-3, whereas SFVs isolated from all Yakushima macaques and one Hondo macaque were classified as genotype 4. Interestingly, genotype 4 was firstly branched off from the rest of the genotypes, which might indicate that the macaques infected with genotype 4 SFV were derived from the "older" population of Japanese macaques. The high prevalence of genotype 4 SFVs among Yakushima macaque might reflect the possibility that they are a descendant of the population settled earlier, which has been geographically isolated in Yakushima Island.