1. Introduction
The
Parvoviridae family is divided into three subfamilies as follows:
Densovirinae,
Hamaparvovirinae, and
Parvovirinae [
1]. The unique
Hamaparvovirinae subfamily can infect a wide range of hosts, including vertebrates and invertebrates [
2].
Chaphamaparvovirus (ChPV) is an important genus of the
Hamaparvovirinae and can infect various animals, such as bats [
3], rodents [
4], birds/poultry [
5,
6,
7,
8], pigs [
9], dogs [
10], domestic cats [
11],
tasmanian devils [
12], wild mammals [
13,
14], and human [
15]. Canine ChPV (CaChPV) and feline ChPV (FeChPV) are classified as
Carnivore chaphamaparvovirus 1 and
Carnivore chaphamaparvovirus 2, respectively [
11,
16]. The complete genome of FeChPV/CaChPV is approximately 3,400 bp in length and contains two major open reading frames: nonstructural protein (NS) and virion protein (VP).
In 2017, a novel parvovirus, termed Cachavirus, was detected in the feces of dogs during an outbreak of diarrhea of an unexplained origin [
10]. It was subsequently detected in Canada, China, and Italy [
16,
17,
18]. Similarly, FeChPV was first detected in Canada during an outbreak of an unknown origin in an animal shelter [
19]. Both CaChPV and FeChPV are supposedly associated with gastrointestinal symptoms and are more frequently detected in animals with diarrhea than that in healthy animals. Further, FeChPV has been detected in cats with respiratory diseases and coinfections with other common viruses [
20].
Previous studies have reported on the cross-host transmission of parvoviruses. Canine parvovirus (CPV) 2a/2b/2c infects cats and causes symptoms similar to those caused by feline parvovirus (FPV) infection in domestic cats [
21,
22]. Mink parvovirus is a variant resulting from the adaptation of the FPV to mink. Interestingly, in China, CaChPV has been detected in cats, while FeChPV has been found in dogs, strongly suggesting a range of host diversity [
17,
23].
In the present study, we focused on the potential of FeChPV and CaChPV for cross-species transmission. A phylogenetic analysis and codon usage analysis revealed the potential host range diversity of the carnivore ChPV and provided additional information to support the understanding of ChPV.
4. Discussion
Chaphamaparvovirus is a recently defined genus in
Parvoviridae family, which comprises a broad reservoir of hosts, including both vertebrates and invertebrates. ChPV is supposedly an ancient virus existing in animal hosts for millions of years [
45]. Further, transmission may have occurred between distantly related host species [
45]. In this study, we detected FeChPV in fecal samples from domestic cats; all positive samples were obtained from domestic cats with diarrhea, thus suggesting FeChPV is associated with diarrhea, similar to CaChPV [
39]. ChPV is often associated with feces, and, therefore, strongly suggests an association with intestinal disease [
45]; however, it supposedly has the potential to cause other diseases, such as respiratory disease [
11], hepatitis [
46], encephalitis [
13], and chronic interstitial nephropathy [
47], in other species. FeChPV was identified in cats exhibiting respiratory symptoms; however, the samples gathered in this study did not include the respiratory tract. As a result, the potential association between the ChPV and respiratory diseases cannot be conclusively assessed, warranting further exploration and study. However, the exact pathogenic capacities of FeChPV and CaChPV have not been confirmed, thus warranting further research.
A previous study reported on CaChPV in domestic cats and FeChPV in dogs [
17,
23]. Therefore, we proposed that it displays a possibility of cross-species transmission. To examine this hypothesis, we performed phylogenetic and codon usage analyses. The phylogenetic analysis demonstrated that ChPV detected in cats displayed higher homology with CaChPV, thus breaking the restrictive host boundary easily. FeChPV and CaChPV are closely related to ChPV isolated from rodents (
Mus musculus),
Sarcophilus harrisii,
Ursus americanus, primate (
Cebus capucinus imitator and Macaca fascicularis), hedgehog (
Erinaceus amurensis), pangolins, and bats. Wildlife, such as pangolins, bats, and hedgehogs, are considered natural hosts for numerous viruses, independent of frequent host spillover events [
48,
49]. Humans are closely associated with dogs and cats, which are companion animals. A unidirectional or bidirectional cross-host transmission of viruses can occur between companion animals and humans [
50,
51]. Therefore, further epidemiological investigations are required to elucidate the close relationship between FeChPV and CaChPV with human and wildlife ChPV in the future.
The CAI value has been used to assess the expression of an exogenous gene within the cell. A high CAI value represents high levels of gene expression and a closer match to the host's codon usage preferences, which may replicate more efficiently [
30]. Therefore, we assessed the CAI values and the similarity of codon usage patterns between FeChPV and CaChPV across various hosts. FeChPV and CaChPV demonstrated greater similarity in the same high-frequency use codons as those in dogs, suggesting that dogs rather than cats are potential hosts for FeChPV and CaChPV. In other words, FeChPV may be able to adapt to dogs, but not cats. Usually, gene expression requires the aid of transfer RNA (tRNA), and the abundance of tRNA corresponding to the codon used in the host gene is higher within the host cell. The differential codon use pattern would limit the rate of viral gene replication because of the use of a low abundance of tRNA. Generally, for exogenous genes, the closer the pattern of use to the host codon, the more efficient the gene expression and the more harmful it is to the host because it inhibits the expression of the host gene [
33,
52]. The CAI, RCID, and SiD analyses yielded similar results. Altogether, this evidence suggests that both FeChPV and CaChPV may infect dogs, while FeChPV or CaChPV can be transmitted between dogs and cats. Notably, the detection of ChPV in the intestine may be a result of food residues caused by a predatory relationship, suggested by the high correlation between ChPV and feces [
45]. In one study, ichthyic ChPV was detected in tilapia-fed crocodiles [
53]. However, the risk of this phenomenon in cats and dogs is low, as these animals do not have a predatory relationship. Therefore, the potential for transmission of ChPV between dogs and cats is high, and the risk of transmission to other hosts should be monitored. The role of a predatory relationship in the cross-species transmission is suggested by the close relationship between FeChPV and rodents ChPV. Moreover, the CAI value is influenced by a multitude of factors, including selection pressure, host codon usage, and mutations, among others [
54]. Consequently, a comprehensive analysis and examination of these pertinent factors is essential for a more accurate understanding.
The CUB analysis demonstrated a weak bias for FeChPV, however, in VP of FeChPV, CUB was stronger than others. CUB causes differences in preferences for using synonymous codons when encoding the same amino acid. Further analysis revealed much lower difference in RSCU values with dogs for both FeChPV and CaChPV. The usage of more similar synonymous codons with the host implies that the virus is able to use the higher abundance of tRNA in the host as raw material for the efficient expression of viral proteins [
52]. Thus, the low variability of FeChPV and CaChPV strongly suggests that this virus is highly adapted to dogs.
The gene mutation pressure, natural selection pressure, secondary protein structure, and external environment are the chief factors contributing to codon bias [
24]. Therefore, we conducted PR2, ENC-plot, and neutrality analyses to evaluate the key dynamics influencing the CUB. Although both mutation and selection pressure play a role in the evolution of codon usage, the selection pressure was the primary influence, similar to CPV, FPV, and feline bocavirus [
24,
55]. CPV-2 constantly generates new subtypes, such as CPV-2C, which have the potential for cross-species transmission [
21]. Selection pressure in virus evolution refers to the various factors and conditions (such as host immune response, antiviral drug and vaccine use, and environmental variables, among others) that drive changes in viral populations over time. These pressures can influence the survival and replication of viral strains, with some variants becoming more successful due to their specific adaptations. The selection pressure drives the process of natural selection, which can result in the emergence of new viral strains with improved fitness in a given environment [
56,
57,
58,
59]. Therefore, the selective pressure on CaChPV and FeChPV warrants attention, and further monitoring of the virus should be intensified to assess its evolutionary status.
Mutation analysis identified co-occurring mutations in cross-species transmitted strains, such as R449K, S197T, and G112R, among others. Notably, some FeChPV mutations correspond to the same amino acids as those in CaChPV, including S197T, D402N, and S206A. While the implications of these mutations for cross-species transmission could not be further explored in this study, they warrant attention. In CPV, specific mutations result in altered host range and receptor-binding capacity [
60]. These mutations do not appear in corresponding B-cell immune epitopes, thus exerting minimal impact on B-cell immunity. Partial immune epitope overlap between CaChPV and FeChPV suggests potential cross-immunity, though experimental validation is required. Consequently, these mutations in CaChPV and FeChPV merit further investigation. Concerning structural similarity, our analysis revealed a high degree of resemblance between VP of cross-species transmissible and non-cross-species transmissible strains. This similarity in VP protein structure suggests a strong potential for binding to respective canine and feline receptors, providing a foundation for infection across different species.
Author Contributions
Conceptualization, W.Y., Y.K., and G.X.; methodology, G.X. Z.Y., and Y.K.; software, G.X. and Z.Y..; validation, G.X., Z.Y. and W.Y.; investigation, P.Y. and T.X.; data curation, W.Y.; writing—original draft preparation, G.X., P.Y., and Z.Y.; writing—review and editing, W.Y. and Y.K..; visualization, G.X. and Z.Y.; supervision, W.Y.; project administration, W.Y.; All authors have read and agreed to the published version of the manuscript.
Figure 1.
Phylogenetic trees of Chaphamaparvovirus based on complete sequence (n=351). Potential cross-species transmission strains are highlighted in red. The feline chaphamaparvovirus obtained in this study uses rectangles to highlight. The best substitution model is GTR+F+R10. Canine bocavirus 2/MG025952.1 is used as an outgroup;.
Figure 1.
Phylogenetic trees of Chaphamaparvovirus based on complete sequence (n=351). Potential cross-species transmission strains are highlighted in red. The feline chaphamaparvovirus obtained in this study uses rectangles to highlight. The best substitution model is GTR+F+R10. Canine bocavirus 2/MG025952.1 is used as an outgroup;.
Figure 2.
Phylogenetic trees of feline chaphamaparvovirus (FeChPV) and canine chaphamaparvovirus (CaChPV) based on NS and VP. (a) NS (n=30); and (b) VP (n=33). The best substitution model is HKY+G4+F. Ursus americanus chapparvovirus/ MN166196.1 is used as an outgroup (Not shown). The red background indicates FeChPV; the blue background indicates CaChPV; Potential cross-species transmission strains are highlighted in red. FigTree and Interactive Tree Of Life are used for visualization. NS, nonstructural protein; VP, virion protein. Outgroup branch not shown.
Figure 2.
Phylogenetic trees of feline chaphamaparvovirus (FeChPV) and canine chaphamaparvovirus (CaChPV) based on NS and VP. (a) NS (n=30); and (b) VP (n=33). The best substitution model is HKY+G4+F. Ursus americanus chapparvovirus/ MN166196.1 is used as an outgroup (Not shown). The red background indicates FeChPV; the blue background indicates CaChPV; Potential cross-species transmission strains are highlighted in red. FigTree and Interactive Tree Of Life are used for visualization. NS, nonstructural protein; VP, virion protein. Outgroup branch not shown.
Figure 3.
Codon usage pattern difference between FechPV/CaChPV and hosts. RCDI: relative synonymous codon usage analysis; SiD: similarity index analysis. The black line represents CaChPV, and the red represents FeChPV. Parametric and non-parametric t tests are used to analyze the significance of Gaussian distribution data and non-conforming data, respectively. **** is defined as p<0.0001; p>0.05 is unlabeled.
Figure 3.
Codon usage pattern difference between FechPV/CaChPV and hosts. RCDI: relative synonymous codon usage analysis; SiD: similarity index analysis. The black line represents CaChPV, and the red represents FeChPV. Parametric and non-parametric t tests are used to analyze the significance of Gaussian distribution data and non-conforming data, respectively. **** is defined as p<0.0001; p>0.05 is unlabeled.
Figure 4.
Analysis of synonymous codon usage preferences between viruses and hosts. The black line represents CaChPV, and the red represents FeChPV. The Shapiro–Wilk test is per-formed for the normality test. Parametric and non-parametric t tests are used to analyze the significance of Gaussian distribution data and non-conforming data, respectively. **** is defined as p<0.0001; p>0.05 is unlabeled.
Figure 4.
Analysis of synonymous codon usage preferences between viruses and hosts. The black line represents CaChPV, and the red represents FeChPV. The Shapiro–Wilk test is per-formed for the normality test. Parametric and non-parametric t tests are used to analyze the significance of Gaussian distribution data and non-conforming data, respectively. **** is defined as p<0.0001; p>0.05 is unlabeled.
Figure 5.
Parity rule 2, ENC-plot, and neutrality analysis based on NS and VP of FeChPV and CaChPV. (a) Parity rule 2; (b) ENC-plot; and (c) neutrality analysis. Red circle and triangle represent the NS and VP of CaChPV; blue circle and triangle represent the NS and VP of FeChPV. NS, nonstructural protein; VP, virion protein; and ENC, effective number of codons.
Figure 5.
Parity rule 2, ENC-plot, and neutrality analysis based on NS and VP of FeChPV and CaChPV. (a) Parity rule 2; (b) ENC-plot; and (c) neutrality analysis. Red circle and triangle represent the NS and VP of CaChPV; blue circle and triangle represent the NS and VP of FeChPV. NS, nonstructural protein; VP, virion protein; and ENC, effective number of codons.
Figure 6.
Heat map of Root Mean Square Deviation of FeChPV and CaChPV. MT123283.1, MY123284.1, MN928791.1, and MN928790.1 are CaChPV, MW396757.1,MW404251.1, OQ162043.1, and OQ162.42.1 are FeChPV. Among them, MN928791.1, MN928790.1, OQ162043.1, and OQ162042.1 are cross-species transmitted strains.
Figure 6.
Heat map of Root Mean Square Deviation of FeChPV and CaChPV. MT123283.1, MY123284.1, MN928791.1, and MN928790.1 are CaChPV, MW396757.1,MW404251.1, OQ162043.1, and OQ162.42.1 are FeChPV. Among them, MN928791.1, MN928790.1, OQ162043.1, and OQ162042.1 are cross-species transmitted strains.
Table 1.
The codon adaptation index of feline chaphamaparvovirus (FeChPV) and canine chaphamaparvovirus (CaChPV).
Table 1.
The codon adaptation index of feline chaphamaparvovirus (FeChPV) and canine chaphamaparvovirus (CaChPV).
|
Viruses |
Dogs (Canis) (Mean±SD) |
Cats (Felis catus) (Mean±SD) |
CAI |
FeChPV |
0.7624±0.0008 |
0.7089±0.0009 |
CaChPV |
0.7485±0.0020 |
0.6950±0.0020 |
eCAI |
FeChPV |
0.7694±0.0017 |
0.7157±0.0016 |
CaChPV |
0.7657±0.0029 |
0.7113±0.0030 |
Normalised CAI (CAI/eCAI) |
FeChPV |
0.9909±0.0024 |
0.9906±0.0033 |
CaChPV |
0.9775±0.0038 |
0.9771±0.0042 |
Table 2.
The effective number of codons of feline chaphamaparvovirus (FeChPV) and canine chaphamaparvovirus (CaChPV).
Table 2.
The effective number of codons of feline chaphamaparvovirus (FeChPV) and canine chaphamaparvovirus (CaChPV).
Virus |
Gene |
Range of ENC |
The average of ENC (?X±S ) |
FeChPV |
NS |
42.6-44.0 |
43.123±0.461 |
VP |
34.2-35.7 |
35.081±0.417 |
CaChPV |
NS |
43.9-46.3 |
45.047±0.613 |
VP |
39.1-41.2 |
40.16±0.761 |
Table 3.
Mutation analysis of cross-species transmission FeChPV and CaChPV strains.
Table 3.
Mutation analysis of cross-species transmission FeChPV and CaChPV strains.
Strains |
Mutation Sites |
CaChPV-MN928790.1 |
I56T, Y68C, F131S, D402N, R449K
|
CaChPV-MN928791.1 |
Y22H, Q365R, R449K, H484P, |
FeChPV-OQ162042.1 |
M19T, G112R, F151S, L174P,S197T, S206A, S325R, E352G, S445N, |
FeChPV-OQ162043.1 |
G112R, L174P, S197T, S325R, |