Modulation of the rate of force development in hip abductor muscles by neuromuscular electrical stimulation during gait.

Purpose/aim of the study: An increase of hip abductor muscle strength contributes to the increase in gait speed. It is known that the rate of force development (RFD), an indicator of muscle strength, is increased by the combined use of low-intensity neuromuscular electrical stimulation (NMES) to the glutaeus medius (GM) and low-load resistance training (RT). However, it is unclear whether low-intensity neuromuscular electrical stimulation of the glutaeus medius during walking also increases the rate of force development. The aim of this study was to clarify whether NMES to the GM during gait modulates the RFD of the hip abductor muscles in healthy adults.Materials and methods: Twenty-two healthy adults randomly received both gait with sub-motor threshold NMES and gait with sham NMES conditions. The RFD was assessed at pre- and post-intervention. A two-way repeated measures analysis of variance was used to analyse the effects of time and intervention.Results: Gait with sub-motor threshold NMES condition significantly increased the RFD in shorter time interval (0-50 and 0-100 ms) compared to gait with sham NMES condition.Conclusions: These findings suggest that the adding low-intensity NMES of the GM to gait is effective in increasing the RFD of the hip abductor muscles.

Phylogenetic analysis of novel posaviruses detected in feces of Japanese pigs with posaviruses and posa-like viruses of vertebrates and invertebrates.

Posaviruses and posa-like viruses are unclassified viruses with sequence similarity to viruses of the order Picornavirales. They have been reported in various vertebrates and invertebrates. We identified 11 posavirus-like sequences in porcine feces and performed phylogenic analysis. Previously reported Japanese posaviruses and those identified in this study clustered with posavirus 1, 4, and 7 and husavirus 1, while five viruses branched into three independent lineages, tentatively named posavirus 10, 11, and 12. Interestingly, posaviruses, except for posavirus 8 and 9, husaviruses, and rasaviruses, formed a cluster consisting of viruses only from pigs, humans, and rats, while posavirus 8 and 9, fisavirus, and basaviruses clustered with posa-like viruses from invertebrates.

Complete genomic analysis and molecular characterization of Japanese porcine sapeloviruses.

The Porcine Sapelovirus (PSV) is an enteric virus of pigs that can cause various disorders. However, there are few reports that describe the molecular characteristics of the PSV genome. In this study, almost the entire genomes of 23 PSVs detected in Japanese pigs were analyzed using bioinformatics. Analysis of the cis-active RNA elements showed that the predicted secondary structures of the internal ribosome entry site in the 5' untranslated region (UTR) and a cis-replication element in the 2C coding region were conserved among PSVs. In contrast, those at the 3' UTR were different for different PSVs; however, tertiary structures between domains were conserved across all PSVs. Phylogenetic analysis of nucleotide sequences of the complete VP1 region showed that PSVs exhibited sequence diversity; however, they could not be grouped into genotypes due to the low bootstrap support of clusters. The insertion and/or deletion patterns in the C-terminal VP1 region were not related to the topology of the VP1 tree. The 3CD phylogenetic tree was topologically different from the VP1 tree, and PSVs from the same country were clustered independently. Recombination analysis revealed that recombination events were found upstream of the P2 region and some recombination breakpoints involved insertions and/or deletions in the C-terminal VP1 region. These findings demonstrate that PSVs show genetic diversity and frequent recombination events, particularly in the region upstream of the P2 region; however, PSVs could currently not be classified into genotypes and conserved genetic structural features of the cis-active RNA elements are observed across all PSVs.

Identification of a novel bovine enterovirus possessing highly divergent amino acid sequences in capsid protein.

BACKGROUND: Bovine enterovirus (BEV) belongs to the species Enterovirus E or F, genus Enterovirus and family Picornaviridae. Although numerous studies have identified BEVs in the feces of cattle with diarrhea, the pathogenicity of BEVs remains unclear. Previously, we reported the detection of novel kobu-like virus in calf feces, by metagenomics analysis. In the present study, we identified a novel BEV in diarrheal feces collected for that survey. Complete genome sequences were determined by deep sequencing in feces. Secondary RNA structure analysis of the 5' untranslated region (UTR), phylogenetic tree construction and pairwise identity analysis were conducted. RESULTS: The complete genome sequences of BEV were genetically distant from other EVs and the VP1 coding region contained novel and unique amino acid sequences. We named this strain as BEV AN12/Bos taurus/JPN/2014 (referred to as BEV-AN12). According to genome analysis, the genome length of this virus is 7414 nucleotides excluding the poly (A) tail and its genome consists of a 5'UTR, open reading frame encoding a single polyprotein, and 3'UTR. The results of secondary RNA structure analysis showed that in the 5'UTR, BEV-AN12 had an additional clover leaf structure and small stem loop structure, similarly to other BEVs. In pairwise identity analysis, BEV-AN12 showed high amino acid (aa) identities to Enterovirus F in the polyprotein, P2 and P3 regions (aa identity ≥82.4%). Therefore, BEV-AN12 is closely related to Enterovirus F. However, aa sequences in the capsid protein regions, particularly the VP1 encoding region, showed significantly low aa identity to other viruses in genus Enterovirus (VP1 aa identity ≤58.6%). In addition, BEV-AN12 branched separately from Enterovirus E and F in phylogenetic trees based on the aa sequences of P1 and VP1, although it clustered with Enterovirus F in trees based on sequences in the P2 and P3 genome region. CONCLUSIONS: We identified novel BEV possessing highly divergent aa sequences in the VP1 coding region in Japan. According to species definition, we proposed naming this strain as "Enterovirus K", which is a novel species within genus Enterovirus. Further genomic studies are needed to understand the pathogenicity of BEVs.

Complete genome analysis of porcine kobuviruses from the feces of pigs in Japan.

Porcine kobuviruses (PoKoVs) are ubiquitously distributed in pig populations worldwide and are thought to be enteric viruses in swine. Although PoKoVs have been detected in pigs in Japan, no complete genome data for Japanese PoKoVs are available. In the present study, 24 nearly complete or complete sequences of the PoKoV genome obtained from 10 diarrheic feces and 14 non-diarrheic feces of Japanese pigs were analyzed using a metagenomics approach. Japanese PoKoVs shared 85.2-100% identity with the complete coding nucleotide (nt) sequences and the closest relationship of 85.1-98.3% with PoKoVs from other countries. Twenty of 24 Japanese PoKoVs carried a deletion of 90 nt in the 2B coding region. Phylogenetic tree analyses revealed that PoKoVs were not grouped according to their geographical region of origin and the phylogenetic trees of the L, P1, P2, and P3 genetic regions showed topologies different from each other. Similarity plot analysis using strains from a single farm revealed partially different similarity patterns among strains from identical farm origins, suggesting that recombination events had occurred. These results indicate that various PoKoV strains are prevalent and not restricted geographically on pig farms worldwide and the coexistence of multiple strains leads to recombination events of PoKoVs and contributes to the genetic diversity and evolution of PoKoVs.

Influence of transcutaneous electrical nerve stimulation conditions on disynaptic reciprocal Ia inhibition and presynaptic inhibition in healthy adults.

This study investigated the influence of stimulus conditions of transcutaneous electrical nerve stimulation (TENS) on disynaptic reciprocal Ia inhibition (RI) and presynaptic inhibition (D1 inhibition) in healthy adults. Eight healthy participants received TENS (stimulus frequencies of 50, 100, and 200 Hz) over the deep peroneal nerve and tibialis anterior (TA) muscle in the resting condition for 30 min. At pre- and post-intervention, the RI from the TA to the soleus (SOL) and D1 inhibition of the SOL alpha motor neuron were assessed by evoked electromyography. The results showed that RI was not changed by TENS at any stimulus frequency condition. Conversely, D1 inhibition was significantly changed by TENS regardless of the stimulus frequency. The present results and previous studies pertaining to RI suggest that the resting condition might strongly influence the lack of pre- vs. post-intervention change in the RI. Regarding the D1 inhibition, the present results suggest that the effect of TENS might be caused by post-tetanic potentiation. The knowledge gained from the present study might contribute to a better understanding of fundamental studies of TENS in healthy adults and its clinical application for stroke survivors.

Characterization and phylogenetic analysis of a novel picornavirus from swine feces in Japan.

During an investigation of porcine fecal viruses using a metagenomics approach, a novel picornavirus was identified from the feces of a healthy two-month-old pig. This virus, named porcine picornavirus Japan (PPVJ), had a standard picornavirus genome organization, including the L protein region. The 5' untranslated region harbored a type II internal ribosomal entry site. This virus was most closely related to lesavirus 1 (amino acid sequence identity: 38.2 %) in P1, equine rhinitis A virus (25.8 %) in P2, and lesavirus 2 (40.9 %) in P3. According to the genus demarcations for the family Picornaviridae (less than 40 %, 40 %, and 50 % amino acid sequence identity in P1, P2, and P3, respectively), PPVJ represents a new genus in the family Picornaviridae. PPVJ was detected in 23.3 % of the fecal samples (from 58.3 % of the farms across a wide area) from pigs less than four months old, by reverse transcription PCR, using specific primers designed from the 3D sequence, followed by sequencing. The host range and pathogenic potential of this virus in animals is yet to be determined.

Identification of further diversity among posaviruses.

Recently, there have been reports of new members of posavirus-like viruses in the order Picornavirales. In this study, using a metagenomics approach, 11 posavirus-like sequences (>7,000 nucleotides) were detected in 155 porcine fecal samples. Phylogenetic analysis revealed that the newly identified virus sequences, together with other posavirus-like viruses, form distinct clusters within the order Picornavirales, composed of eight genogroups and unassigned sequences based on amino acid sequences of the helicase and RNA-dependent RNA polymerase regions, with <40 % and <50 % sequence identity, respectively. We propose further classifications of highly diverse posavirus populations based on newly identified sequences from Japanese pig feces.

Full genome analysis of bovine astrovirus from fecal samples of cattle in Japan: identification of possible interspecies transmission of bovine astrovirus.

A viral metagenomics approach was used to investigate fecal samples of Japanese calves with and without diarrhea. Of the different viral pathogens detected, read counts gave nearly complete astrovirus-related RNA sequences in 15 of the 146 fecal samples collected in three distinct areas (Hokkaido, Ishikawa, and Kagoshima Prefectures) between 2009 and 2015. Due to the lack of genetic information about bovine astroviruses (BoAstVs) in Japan, these sequences were analyzed in this study. Nine of the 15 Japanese BoAstVs were closely related to Chinese BoAstVs and clustered into a lineage (tentatively named lineage 1) in all phylogenetic trees. Three of 15 strains were phylogenetically separate from lineage 1, showing low sequence identities, and clustered instead with an American strain isolated from cattle with respiratory disease (tentatively named lineage 2). Interestingly, two of 15 strains clustered with lineage 1 in the open reading frame (ORF)1a and ORF1b regions, while they clustered with lineage 2 in the ORF2 region. Remarkably, one of 15 strains exhibited low amino acid sequence similarity to other BoAstVs and was clustered separately with porcine astrovirus type 5 in all trees, and ovine astrovirus in the ORF2 region, suggesting past interspecies transmission.

The effect of gait training with low-intensity neuromuscular electrical stimulation of hip abductor muscles in two patients following surgery for hip fracture: Two case reports.

BACKGROUND: The rate of force development (RFD) is an indicator of muscle strength. A previous study reported that the RFD of hip abductor muscles was increased by neuromuscular electrical stimulation (NMES) to gluteus medius (GM) during gait in healthy adults. However, the effects for patients following femoral head replacement for hip fracture are unclear. PURPOSE: The aim of this case report was to investigate the effects of gait training with sub-motor threshold NMES on RFD of hip abductor muscles in two patients following femoral head replacement for hip fracture compared to gait training without NMES. CASE DESCRIPTION: Two elderly patients following femoral head replacement for hip fracture received both interventions of gait training with sub-motor threshold NMES to GM and without NMES. Intervention phases involved 14 sessions each, for 28 sessions total. OUTCOMES: The RFD of hip abductor muscles, maximum walking speed, six-minute walk distance (6MWD), Berg Balance Scale, one-leg standing time (OLST), functional independence measure, and Numeric Pain Rating Scale (NPRS) were used as outcome measures. In both patients, RFD, 6MWD, OLST, and NPRS were improved by gait training with NMES compared to without NMES. CONCLUSION: Our results suggest the potential of NMES as a treatment methodology for these two patients undergoing femoral head replacement for hip fracture.

Effect of Lee Silverman Voice Treatment (LSVT)® BIG on motor symptoms in a patient with severe Parkinson's disease: a case report.

INTRODUCTION: Lee Silverman Voice Treatment® BIG (LSVT® BIG) is widely used to improve motor symptoms in patients with mild-to-moderate Parkinson's disease (PD). OBJECTIVE: To describe the effect of LSVT® BIG on the motor symptoms of a patient with severe PD. CASE DESCRIPTION: A 77-year-old woman who was diagnosed with PD received a 4-week LSVT® BIG program under the supervision of certified LSVT® BIG physical therapists. Her disease severity was classified as Hoehn and Yahr stage 4. The unified Parkinson's disease rating scale (UPDRS) part 3, 10-m walk test (10MWT), timed up-and-go test (TUG), Berg balance scale (BBS), and 30-s chair stand test (30-s CST) were used for assessment before and after intervention. OUTCOMES: The UPDRS part 3, 10MWT, TUG, BBS, and 30-s CST improved after intervention (33 to 26, 0.51 to 0.69 m/s, 38.1 to 23.2 seconds, 11 to 34, and 3 to 9 times, respectively). All improvements exceeded the Minimal Clinically Important Difference or Minimal Detectable Change values (2.5, 0.16 m/s, 3.5 seconds, 5, and 3 times, respectively). CONCLUSIONS: These results indicated that LSVT® BIG appears to have improved motor symptoms in a patient with severe PD. Further studies, ideally randomized controlled trials, are needed to confirm these findings.

Complete genome sequencing and genetic characterization of porcine sapovirus genogroup (G) X and GXI: GVI, GVII, GX, and GXI sapoviruses share common genomic features and form a unique porcine SaV clade.

Sapoviruses (SaVs) are enteric viruses belonging to the family Caliciviridae that infect humans and animals, including pigs. To date, SaVs have been classified into 19 genogroups (G) based on complete VP1 sequences; however, complete genome sequences of some SaV Gs are not yet available. In this study, we determined the full genome sequences of four SaVs (two GX and two GXI SaVs) and analyzed them together with those of other SaVs. The complete genome sequences of GX and GXI SaVs, excluding the poly(A) tails, were 7124, 7142, 7170, and 7179 nucleotides, which were shorter than those of other SaVs, except for porcine GVI and GVII viruses. Genetic characterization revealed that GX SaVs and GXI SaVs shared common features with GVI and GVII viruses, such as the first 10 amino acid residues in the ORF1 coding region, a shorter ORF1 than that of the other genogroups, and the predicted secondary structure of the 5' end of the genome and the starting region of non-structural protein/structural protein junction. Phylogenetic analyses showed that GX and GXI SaVs branched with porcine GVI, GVII, and GIX SaVs and formed a clade consisting of only porcine SaVs. These findings suggest that porcine GX and GXI SaVs together with porcine GVI, GVII, and possibly GIX SaVs, evolved from a common ancestor in the porcine population.

A novel defective recombinant porcine enterovirus G virus carrying a porcine torovirus papain-like cysteine protease gene and a putative anti-apoptosis gene in place of viral structural protein genes.

Enterovirus G (EV-G) belongs to the family of Picornaviridae. Two types of recombinant porcine EV-Gs carrying papain-like cysteine protease (PLCP) gene of porcine torovirus, a virus in Coronaviridae, are reported. Type 1 recombinant EV-Gs are detected in pig feces in Japan, USA, and Belgium and carry the PLPC gene at the junction site of 2C/3A genes, while PLPC gene replaces the viral structural genes in type 2 recombinant EV-G detected in pig feces in a Chinese farm. We identified a novel type 2 recombinant EV-G carrying the PLCP gene with flanking sequences in place of the viral structural genes in pig feces in Japan. The ~0.3 kb-long upstream flanking sequence had no sequence homology with any proteins deposited in GenBank, while the downstream ~0.9 kb-long flanking sequence included a domain having high amino acid sequence homology with a baculoviral inhibitor of apoptosis repeat superfamily. The pig feces, where the novel type 2 recombinant EV-G was detected, also carried type 1 recombinant EV-G. The amount of type 1 and type 2 recombinant EV-G genomes was almost same in the pig feces. Although the phylogenetic analysis suggested that these two recombinant EV-Gs have independently evolved, type 1 recombinant EV-G might have served as a helper virus by providing viral structural proteins for dissemination of the type 2 recombinant EV-G.

Relationship between the rate of force development in knee extensor muscles and gait speed in patients with chronic stroke: A cross-sectional study.

BACKGROUND: The relationship between peak torque of the knee extensor muscles and gait speed was previously investigated in patients with chronic stroke, but whether the rate of force development (RFD), another indicator of muscle strength, affected gait speed remained unknown. OBJECTIVE: To clarify the relationships between the RFD of the knee extensor muscles over multiple time intervals and gait speed in patients with chronic stroke. METHODS: Twenty chronic stroke patients participated in this study. The RFD of affected and unaffected knee extensor muscles was measured. Time intervals of the RFD were set to 0-50 ms, 0-100 ms (100RFD), 0-200 ms (200RFD), and 0-300 ms (300RFD). Gait speed was assessed at comfortable and maximum pace. Pearson correlation coefficient (r) was used to analyze the relationships between RFD and gait speeds. RESULTS: The RFD of affected knee extensor muscles over all intervals was moderately correlated with both comfortable and maximum gait speeds, whereas only limited combinations (100, 200 and 300RFD with maximum gait speed) were correlated on the unaffected side. CONCLUSIONS: The present results suggest that various factors related to the RFD of affected knee extensor muscles, such as neural drive and muscle size, affect gait speed.

Whole genome analysis of a novel picornavirus related to the Enterovirus/Sapelovirus supergroup from porcine feces in Japan.

A novel virus related to the Enterovirus/Sapelovirus supergroup in the family Picornaviridae was identified in healthy porcine feces in Japan by using a metagenomics approach. The genome of the virus, named Sapelo-like porcine picornavirus Japan (SPPVJ) Pig/Isi-Im1/JPN/2016, had a type-IV internal ribosomal entry site and carried a 6978-nucleotide-long single open reading frame encoding a 2326 amino acids (aa) polyprotein precursor. The coding sequence region consisted of leader protein (68 aa), a structural protein region P1 (824 aa), and the non-structural protein regions P2 (672 aa) and P3 (762 aa). Among representative picornaviruses, the P1, 2C, and 3CD regions of SPPVJ had the highest aa identities of 64.4%, 61.9%, and 73.3%, respectively, with the corresponding regions of sapelo-like bat picornavirus BtVs-PicoV/SC2013. Sequencing analysis of the RT-PCR products derived from the 5' untranslated and 3D regions revealed the presence of SPPVJ in 17.8% (19/107) of the feces from healthy and diarrheal pigs in 12 farms in 2015-2016. Further studies are needed to determine the origin and pathogenic potential of SPPJV in pigs and other mammals.

Metagenomic identification and sequence analysis of a Teschovirus A-related virus in porcine feces in Japan, 2014-2016.

Porcine Teschoviruses (PTVs) are associated with polioencephalomyelitis and various diseases, including reproductive and gastrointestinal disorders, of pigs and wild boars, and are also detected in the feces of healthy pigs. The genus Teschovirus contains a single species Teschovirus A that currently includes 13 serotypes. In the present study, we identified novel PTVs that are distantly related to Teschovirus A and were found in fecal samples of pigs with or without diarrhea in Japan. Phylogenetic analysis of amino acid (aa) sequences of the complete coding region revealed that these newly identified viruses did not cluster with any strains of PTVs or other strains within the picornavirus supergroup 1, suggesting that the viruses may not belong to Teschovirus A or any genus of the family Picornaviridae. These novel PTVs share a type IV internal ribosomal entry site and conserved characteristic motifs in the coding region, yet exhibit 62.2-79.0%, 86.6-92.8%, 77.1-81.0%, and 84.3-86.7% aa identities to PTV strains in P1, 2C, 3C, and 3D regions, respectively. In contrast, PTV 1-13 strains of the Teschovirus A share 76.5-92.1%, 88.1-99.7%, 93.2-100%, and 95.8-100% aa identities in the P1, 2C, 3C, and 3D, respectively, within the species. These data imply that the newly identified viruses belong to teschoviruses, and may represent a novel species in the genus Teschovirus.

Elucidating the Crystallite Size Dependence of the Thermochromic Properties of Nanocomposite VO2 Thin Films.

Fenestration elements that enable spectrally selective dynamic modulation of the near-infrared region of the electromagnetic spectrum are of great interest as a means of decreasing the energy consumption of buildings by adjusting solar heat gain in response to external temperature. The binary vanadium oxide VO2 exhibits a near-room-temperature insulator-metal electronic transition accompanied by a dramatic modulation of the near-infrared transmittance. The low-temperature insulating phase is infrared transparent but blocks infrared transmission upon metallization. There is considerable interest in harnessing the thermochromic modulation afforded by VO2 in nanocomposite thin films. However, to prepare a viable thermochromic film, the visible-light transmittance must be maintained as high as possible while maximizing thermochromic modulation in the near-infrared region of the electromagnetic spectrum, which necessitates the development of high-crystalline-quality VO2 nanocrystals of the optimal particle size embedded within the appropriate host matrix and refractive index matched to the host medium. Here, we demonstrate the preparation of acrylate-based nanocomposite thin films with varying sizes of embedded VO2 nanoparticles. The observed strong size dependence of visible-light transmittance and near-infrared modulation is explicable on the basis of optical simulations. In this article, we elucidate multiple scattering and absorption mechanisms, including Mie scattering, temperature-/phase-variant refractive-index mismatch between VO2 nanocrystals and the encapsulating matrix, and the appearance of a surface plasmon resonance using temperature-variant absorptance and diffuse transmittance spectroscopy measurements performed as a function of particle loading for the different sizes of VO2 nanocrystals. Nanocrystals with dimensions of 44 ± 30 nm show up to >32% near-infrared energy modulation across the near-infrared region of the electromagnetic spectrum while maintaining high visible-light transmission. The results presented here, providing mechanistic elucidation of the size dependence of the different scattering mechanisms, underscore the importance of nanocrystallite dimensions, refractive-index matching, and individualized dispersion of particles within the host matrix for the preparation of viable thermochromic thin films mitigating Mie scattering and differential refractive-index scattering.

Genetic diversity and recombination of enterovirus G strains in Japanese pigs: High prevalence of strains carrying a papain-like cysteine protease sequence in the enterovirus G population.

To study the genetic diversity of enterovirus G (EV-G) among Japanese pigs, metagenomics sequencing was performed on fecal samples from pigs with or without diarrhea, collected between 2014 and 2016. Fifty-nine EV-G sequences, which were >5,000 nucleotides long, were obtained. By complete VP1 sequence analysis, Japanese EV-G isolates were classified into G1 (17 strains), G2 (four strains), G3 (22 strains), G4 (two strains), G6 (two strains), G9 (six strains), G10 (five strains), and a new genotype (one strain). Remarkably, 16 G1 and one G2 strain identified in diarrheic (23.5%; four strains) or normal (76.5%; 13 strains) fecal samples possessed a papain-like cysteine protease (PL-CP) sequence, which was recently found in the USA and Belgium in the EV-G genome, at the 2C-3A junction site. This paper presents the first report of the high prevalence of viruses carrying PL-CP in the EV-G population. Furthermore, possible inter- and intragenotype recombination events were found among EV-G strains, including G1-PL-CP strains. Our findings may advance the understanding of the molecular epidemiology and genetic evolution of EV-Gs.

Discovery of fur seal feces-associated circular DNA virus in swine feces in Japan.

Fur seal feces-associated circular ssDNA virus (FSfaCV) was discovered in a pig for the first time in Japan using a next-generation sequencer with duplex-specific nuclease. Full genome of the virus showed approximately 92% similarity to FSfaCVs from New Zealand fur seals. Furthermore, we investigated the prevalence of the ssDNA virus in 85 piglets in Japan, and 65 piglets were positive (76%) for the virus.

Whole genome analysis of porcine astroviruses detected in Japanese pigs reveals genetic diversity and possible intra-genotypic recombination.

Porcine astroviruses (PoAstVs) are ubiquitous enteric virus of pigs that are distributed in several countries throughout the world. Since PoAstVs are detected in apparent healthy pigs, the clinical significance of infection is unknown. However, AstVs have recently been associated with a severe neurological disorder in animals, including humans, and zoonotic potential has been suggested. To date, little is known about the epidemiology of PoAstVs among the pig population in Japan. In this report, we present an analysis of nearly complete genomes of 36 PoAstVs detected by a metagenomics approach in the feces of Japanese pigs. Based on a phylogenetic analysis and pairwise sequence comparison, 10, 5, 15, and 6 sequences were classified as PoAstV2, PoAstV3, PoAstV4, and PoAstV5, respectively. Co-infection with two or three strains was found in individual fecal samples from eight pigs. The phylogenetic trees of ORF1a, ORF1b, and ORF2 of PoAstV2 and PoAstV4 showed differences in their topologies. The PoAstV3 and PoAstV5 strains shared high sequence identities within each genotype in all ORFs; however, one PoAstV3 strain and one PoAstV5 strain showed considerable sequence divergence from the other PoAstV3 and PoAstV5 strains, respectively, in ORF2. Recombination analysis using whole genomes revealed evidence of multiple possible intra-genotype recombination events in PoAstV2 and PoAstV4, suggesting that recombination might have contributed to the genetic diversity and played an important role in the evolution of Japanese PoAstVs.