MBE Advance Access originally published online on April 15, 2008
Molecular Biology and Evolution 2008 25(7):1488-1492; doi:10.1093/molbev/msn093
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Research Articles |
High Rates of Molecular Evolution in Hantaviruses




* Department of Biology, Center for Infectious Disease Dynamics, The Pennsylvania State University
LEMB, Institute of Biomedical Science, University of São Paulo, São Paulo, SP, Brazil
School of Medicine, University of São Paulo, Ribeirão Preto, SP, Brazil
Fogarty International Center, National Institutes of Health, Bethesda, MD
E-mail: pzanotto{at}usp.br
| Abstract |
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Hantaviruses are rodent-borne Bunyaviruses that infect the Arvicolinae, Murinae, and Sigmodontinae subfamilies of Muridae. The rate of molecular evolution in the hantaviruses has been previously estimated at approximately 10–7 nucleotide substitutions per site, per year (substitutions/site/year), based on the assumption of codivergence and hence shared divergence times with their rodent hosts. If substantiated, this would make the hantaviruses among the slowest evolving of all RNA viruses. However, as hantaviruses replicate with an RNA-dependent RNA polymerase, with error rates in the region of one mutation per genome replication, this low rate of nucleotide substitution is anomalous. Here, we use a Bayesian coalescent approach to estimate the rate of nucleotide substitution from serially sampled gene sequence data for hantaviruses known to infect each of the 3 rodent subfamilies: Araraquara virus (Sigmodontinae), Dobrava virus (Murinae), Puumala virus (Arvicolinae), and Tula virus (Arvicolinae). Our results reveal that hantaviruses exhibit short-term substitution rates of 10–2 to 10–4 substitutions/site/year and so are within the range exhibited by other RNA viruses. The disparity between this substitution rate and that estimated assuming rodent–hantavirus codivergence suggests that the codivergence hypothesis may need to be reevaluated.
Key Words: hantavirus nucleotide substitution molecular evolution substitution rates
| Introduction |
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Hantaviruses are negative-sense single-stranded, enveloped RNA viruses, with a genome comprising 3 segments: S (small), M (medium), and L (large), encoding the nucleocapsid (N) protein, the envelope glycoproteins (G1 and G2), and the RNA-dependent RNA polymerase, respectively (Schmaljohn 1996
Phylogenetic studies of the genus have consistently found that hantaviruses cluster into 3 primary clades associated with the rodent subfamily each virus infects: Arvicolinae, Sigmodontinae, and Murinae. This association has been the basis of the hypothesis that hantaviruses have codiverged with their rodent hosts since the common ancestor of the 3 rodent subfamilies, an estimate that places the age of hantaviruses to be tens of millions of years (Hjelle et al. 1995
; Plyusnin et al. 1996
; Morzunov et al. 1998
; Monroe et al. 1999
; Vapalahti et al. 1999
; Hughes and Friedman 2000
; Plyusnin and Morzunov 2001
; Jackson and Charleston 2004
). Based on this assumption of codivergence, the rate of molecular evolutionary change in hantaviruses has been estimated between 2 x 10–6 and 3 x 10–7 nucleotide substitutions per site, per year (2.41 x 10–7 to 2.68 x 10–7 substitutions/site/year, Hughes and Friedman 2000
; 2.2 x 10–6 to 7.0 x 10–6 substitutions/site/year, Sironen et al. 2001
). These substitution rates are a substantial departure from those estimated for other RNA viruses, which generally fall within the range of 10–3 to 10–4 substitutions/site/year (Jenkins et al. 2002
; Hanada et al. 2004
) and which are evidently a function of high intrinsic rates of mutation coupled with rapid replication. If substantiated, the rodent hantaviruses would therefore be among the most slowly evolving of all RNA viruses.
Given that all RNA viruses replicate using an RNA-dependent RNA polymerase that does not possess proofreading or error correction, the most likely mechanistic explanation for an anomalously low rate of molecular evolution in the hantaviruses is that replication rates (generation times) have been greatly reduced in these viruses. Specifically, because hantaviruses generate persistent infections in their reservoir hosts, it has been widely assumed that they are latent within hosts, undergoing little to no viral replication following acute infection. Indeed, a reduced rate of replication has been proposed to reduce long-term evolutionary rates in the retrovirus human T-cell lymphotropic virus (HTLV), producing substitution rates in the order of
10–7 substitutions/site/year (Salemi et al. 1999
; Hanada et al. 2004
), although unlike hantavirus HTLV is able to integrate into host genomes and therefore replicate with higher fidelity DNA polymerases. However, recent work suggests that hantavirus infection may not be latent because viral RNA can be detected sporadically by polymerase chain reaction throughout the course of infection (Botten et al. 2003
; Kuenzi et al. 2005
).
Critically, all estimates of rates of molecular evolution in the hantaviruses undertaken to date have assumed a codivergence between the viruses with their rodent hosts. Although we do not test the hypothesis of codivergence explicitly here, an independent and direct estimate of the rate at which hantaviruses evolve is a necessary first step toward validating this widely accepted view of hantavirus evolution. Indeed, one of the key factors that must be true for any proposal of host–parasite codivergence to be plausible is that the timescales over which the host and parasite groups have diverged are congruent (Page 1996
). To this end, we estimate rates of nucleotide substitution in each of the 3 major clades of rodent hantavirus using serially sampled data, in which the extent of genetic divergence among viruses sampled at different times is used to infer fundamental evolutionary dynamics.
| Materials and Methods |
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Data Sets
All hantavirus sequences for which the date (day or year) of sampling was available were downloaded from GenBank, and each hantavirus with greater than 20 available sequences was retained for analysis. Under these criteria, the nucleocapsid genes from 3 hantaviruses were chosen for further analysis: Dobrava virus (n = 30, 1,302 bp, sampled from 1985 to 2006) which infects Murinae rodents, along with the Puumala (n = 59, 1,302 bp, sampled from 1979 to 2004) and Tula viruses (n = 23, 1,293 bp, sampled from 1987 to 1996) which infect Arvicolinae rodents. As there was no data set available from GenBank for those hantaviruses that infect Sigmodontinae rodents, we obtained sera samples from patients diagnosed with HPS or wild rodents collected near human outbreak sites in the states of Sao Paulo, Minas Gerais, Santa Catarina, and the Federal District, Brazil (table 1). From these samples, 312 bp of G1 sequences (n = 32), 302 bp of G2 sequences (n = 13), and 261 bp of N sequences (n = 33) were recovered from whole genomic RNA (Figueiredo LM, Moreli ML, de Sousa RLM, Borges AA, de Figueiredo GG, Machado AM, Bisordi I, Nagasse-Sugahara TK, Suzuki A, Pereira LE, de Souza RP, de Souza LTM, Braconi CT, Zanotto PM de A, and the VGDN consortium, in preparation). These Brazilian hantavirus sequences were identified as Araraquara through phylogenetic comparison with North and South American hantavirus sequences taken from GenBank (Figueiredo et al., in preparation—trees available on request). Prior to estimating the substitution dynamics of these 5 hantavirus data sets, all sequences were aligned manually using Se-Al (v2.0a11 Carbon, http://evolve.zoo.ox.ac.uk) and examined for evidence of recombination using the RDP3 program (Martin et al. 2005
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Rates of molecular evolution (substitutions/site/year) were estimated for each taxon (and gene) individually using the Bayesian Markov chain Monte Carlo (MCMC) method available in the BEAST package v1.4.6 (Drummond and Rambaut 2007
4 model. Sequences were dated according to the year of sampling for Dobrava, Puumala, and Tula viruses and the day of sampling for Araraquara virus. Coalescent analyses were run until all parameters converged, with confidence intervals given by the 95% highest probability density (HPD). Data sets were analyzed using both a strict and relaxed molecular clock with an uncorrelated lognormal rate distribution, using a range of prior values for the substitution rate, and under demographic models of 1) a constant population size, 2) exponential population growth, and 3) logistic population growth. | Results and Discussion |
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As we observed no recombinant sequences in any of the data sets, all available sequences were used to estimate the evolutionary dynamics of Araraquara, Dobrava, Puumala, and Tula viruses. The mean rate of molecular evolution estimated for these hantaviruses across all clocks and demographic models in our Bayesian coalescent analyses ranged from 2.10 x 10–2 to 2.66 x 10–4 substitutions/site/year (table 2). Importantly, these values are several orders of magnitude higher than any previous estimates given for the evolutionary dynamics of hantaviruses based on the assumption of host–parasite codivergence. Further, similar mean substitution rates were recovered when far lower (1.0 x 10–8 substitutions/site/year) prior probability values were used. By including all models regardless of their likelihood and posterior probability, our evolutionary rates are conservative in their estimates and have 95% HPD values that vary widely between models. These values ranged from 3.15 x 10–8 under the least optimal model for Dobrava virus to 3.28 x 10–2 substitutions/site/year for Tula virus (table 2). Although values in the range of 10–8 are consistent with those previously estimated under the hypothesis of codivergence, it is important to note that this value is a clear outlier across the analysis as a whole and is distinct from the mean rate estimated for this virus (
3 x 10–4 substitutions/site/year). However, the wide distribution of sampling error in our estimates highlights both the inherent difficulties in working with the small data sets that are available for hantaviruses and the clear need for larger data sets of dated sequences.
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An additional issue of importance, when inferring evolutionary dynamics from sequence data sampled over a relatively short time period and from closely related taxa, is the difficulty in separating the relative contributions of the mutation and substitution rates. In particular, the Araraquara data set was sampled over only 6 years so that the number of nucleotide substitutions measured may in fact include slightly deleterious mutations that would later be purged by purifying selection, thereby artificially inflating estimates. However, our Dobrava and Puumala data sets included many more sequences sampled over longer time intervals and hence many more viral generations, providing more time for selective effects to be observed. As such, the mean rates measured for these 2 taxa (
3 x 10–4 and
5.5 x 10–4 substitutions/site/year for Dobrava and Puumala viruses, respectively) may more accurately represent the true substitution rates for the Hantavirus genus. Additional sampling over longer time periods would further clarify the long-term evolutionary rates of these viruses.
This study has demonstrated that the mean rate of evolutionary change in hantaviruses is approximately within the range of 10–2 to 10–4 substitutions/site/year, an estimate concordant with those of the majority of other RNA viruses (Jenkins et al. 2002
; Hanada et al. 2004
). Substitution rates in the order of 10–3 are not unexpected because hantaviruses rely on RNA-dependent RNA polymerase for replication, which lacks mechanisms of proofreading and repair mechanisms and which possesses an error rate of
1 mutation/replication/genome (Drake 1999
). Indeed, previous work has calculated the mutational frequency for hantaviruses to be in the range of 1 x 10–3 to 3 x 10–3, with intrahost genetic variation approaching that seen in HIV and hepatitis C (Plyusnin et al. 1995
, 1996
; Feuer et al. 1999
). As a consequence, it does not seem unreasonable for this mutation rate to translate to the substitution rates of the order of 10–4 substitutions/site/year observed here. In contrast, for a mutation rate of this order to translate into a substitution rate of 10–6 to 10–7 substitutions/site/year, hantaviruses would have to replicate only once every 1.33 years (assuming a genome of 10 kb and a neutral evolutionary process). Considering the average rodent life span in the wild is likely to be only a year or 2, this replication rate would seemingly create implausible conditions for effective transmission (de Oliveira et al. 1998
). A rapid mutation rate could also translate into a low substitution rate if hantaviruses became latent following the acute phase of infection, a widely held assumption for infection in rodent hosts. However, recent studies using more sensitive methods have detected viral RNA in the blood intermittently over the course of long-term infection, indicating continuous viral replication even after the acute phase of infection (Hutchinson et al. 1998
; Feuer et al. 1999
; Botten et al. 2003
; Kuenzi et al. 2005
). As such, it is extremely difficult to reconcile a mutation rate of 10–3 with a substitution rate of 10–7 within the context of hantavirus biology.
Previous estimates of evolutionary dynamics in hantaviruses were based on the critical assumption that the congruence between hantavirus and rodent phylogenies reflects codivergence between these 2 groups since the divergence of the rodent genera Mus and Rattus, approximately 10–40 MYA (Hughes and Friedman 2000
; Sironen et al. 2001
; Nemirov et al. 2002
). However, the observation of host–pathogen phylogenetic congruence does not necessarily indicate codivergence. Phylogenetic congruence between a parasite and its host can also arise from delayed cladogenesis, where the parasite phylogeny tracks that of the host but without temporal association (Jackson and Charleston 2004
). This could occur if hantaviruses largely evolve host associations by cross-species transmission and related species tend to live in the same area, in which case a pattern of strong host–pathogen phylogenetic congruence could be observed in the absence of codivergence. In contrast to previous work, our evolutionary rates were estimated directly from primary sequence data sampled at known dates so that they more closely reflect the evolutionary changes undergone by the virus, at least in the short term. At the very least, the observation that hantaviruses exhibit short-term evolutionary rates equivalent to those seen in rapidly evolving RNA viruses makes a stringent reevaluation of the codivergence hypothesis necessary (Adkins et al. 2003
).
| Accession Numbers |
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The GenBank accession numbers of the Araraquara virus sequences determined for use in this study are: EU170207 [GenBank] –EU170239 [GenBank] (N), EU170162 [GenBank] –EU170193 [GenBank] (G1), and EU170194 [GenBank] –EU170206 [GenBank] (G2).
The GenBank accession numbers for the sequences retrieved from previously published studies are:
- Dobrava virus: DQ305279
[GenBank]
, AJ009773
[GenBank]
, AJ009775
[GenBank]
, AF060014
[GenBank]
, AF060015
[GenBank]
, AF060016, AF060017
[GenBank]
, AF060018
[GenBank]
, AF060019
[GenBank]
, AF060020
[GenBank]
, AF060021
[GenBank]
, AF060022, AF060023
[GenBank]
, AF060024
[GenBank]
, AJ410615
[GenBank]
, AJ410619
[GenBank]
, NC_00523, EF028074, EF059978
[GenBank]
, EF059979
[GenBank]
, EF059980
[GenBank]
, AF442622
[GenBank]
, AF442623
[GenBank]
, AJ131672, AJ131673
[GenBank]
, AJ251996
[GenBank]
, AJ251997
[GenBank]
, AY168576
[GenBank]
, AY961615
[GenBank]
, and AY961618.
- Puumala virus: AJ888751
[GenBank]
, AJ888752
[GenBank]
, PVU95306, AJ277030
[GenBank]
, AJ277031
[GenBank]
, AJ277032, AJ277033
[GenBank]
, AJ277034
[GenBank]
, AJ238791
[GenBank]
, AJ278092
[GenBank]
, AJ278093
[GenBank]
, AB010730, AB010731
[GenBank]
, AJ314597
[GenBank]
, AJ314598
[GenBank]
, AJ314599
[GenBank]
, AJ314600
[GenBank]
, AJ314601, Z21497_1, Z30702_1, Z30703_1, Z30704_1, Z30705_1, Z30706_1, Z30707_1, Z30708_1, Z46942_1, Z69985_1, AJ223368
[GenBank]
, AJ223369, AJ223371
[GenBank]
, AJ223374
[GenBank]
, AJ223375
[GenBank]
, AJ223376
[GenBank]
, AJ223377
[GenBank]
, AJ223380, AF367064
[GenBank]
, AF367065
[GenBank]
, AF367066
[GenBank]
, AF367067
[GenBank]
, AF367068
[GenBank]
, AF367069, AF367070
[GenBank]
, AF367071
[GenBank]
, AF411447
[GenBank]
, AF411448
[GenBank]
, AF411449
[GenBank]
, AF442613, AJ238788
[GenBank]
, AJ238789
[GenBank]
, AJ238790
[GenBank]
, AJ888731
[GenBank]
, AJ888732
[GenBank]
, AJ888733, AJ888734
[GenBank]
, AJ888735
[GenBank]
, AJ888736
[GenBank]
, AJ888738
[GenBank]
, and Z48586.
[GenBank]
- Tula virus: U95302
[GenBank]
, U95303
[GenBank]
, U95304
[GenBank]
, U95305
[GenBank]
, U95309
[GenBank]
, U95310
[GenBank]
, U95311, U95312
[GenBank]
, NC_005227
[GenBank]
, Z30941
[GenBank]
, Z30942
[GenBank]
, Z30943
[GenBank]
, Z30944
[GenBank]
, Z30945
[GenBank]
, Z48573, Z48574
[GenBank]
, Z48741
[GenBank]
, AF063892
[GenBank]
, AF063897
[GenBank]
, AJ223600
[GenBank]
, AJ223601
[GenBank]
, Y13979, and Y13980.
[GenBank]
| Acknowledgements |
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This work was funded by the Fundação de Amparo a Pesquisa do Estado de São Paulo (# 00/04205-6) as part of the Viral Genetic Diversity (VGDN) Program. Funding to P.M.A.Z. was provided by Conselho Nacional de Desenvolvimento Cientifico e Tecnologico, F.L.M. was provided by a Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior scholarship, and C.R. received funding from Natural Sciences and Engineering Reserach Council of Canada. The VGDN Consortium is: Marcos Lázaro Moreli, Ricardo Luiz Moro de Sousa, Alessandra Abel Borges, Glauciane Garcia de Figueiredo, Ivani Bisordi, Teresa Keiko Nagasse-Sugahara, Akemi Suzuki, Luiz Eloy Pereira, Renato Pereira de Souza, Luiza Terezinha Madia de Souza, Carla Torres Braconi, and Jansen Araujo.
| Footnotes |
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Peter Lockhart, Associate Editor
| References |
|---|
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|
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Adkins RM, Walton AH, Honeycutt RL. Higher-level systematics of rodents and divergence time estimates based on two congruent nuclear genes. Mol Phylogenet Evol (2003) 26:409–420.[CrossRef][Web of Science][Medline]
Botten J, Mirowsky K, Kusewitt D, Ye C, Gottlieb K, Prescott J, Hjelle B. Persistent Sin Nombre virus infection in the deer mouse (Peromyscus maniculatus) model: sites of replication and strand-specific expression. J Virol (2003) 77:1540–1550.[CrossRef][Web of Science][Medline]
de Oliveira JA, Strauss RE, dos Reis SF. Assessing relative age and age structure in natural populations of Bolomys lasiurus (Rodentia: Sigmodontinae) in northeastern Brazil. J Mammal (1998) 79:1170–1183.[CrossRef][Web of Science]
Drake JW. The distribution of rates of spontaneous mutation over viruses, prokaryotes, and eukaryotes. Ann N Y Acad Sci (1999) 870:100–107.[CrossRef][Web of Science][Medline]
Drummond AJ, Rambaut A. BEAST: Bayesian evolutionary analysis by sampling trees. BMC Evol Biol (2007) 7:214.[CrossRef][Medline]
Feuer R, Boone JD, Netski D, Morzunov SP, St. Jeor SC. Temporal and spatial analysis of Sin Nombre virus quasispecies in naturally infected rodents. J Virol (1999) 73:9544–9554.
Hanada K, Suzuki Y, Gojobori T. A large variation in the rates of synonymous substitution for RNA viruses and its relationship to a diversity of viral infection and transmission modes. Mol Biol Evol (2004) 21:1074–1080.
Hjelle B, Lee S-W, Song W, Torrez-Martinez N, Song J-W, Yanagihara R, Gavrilovskaya I, Mackow ER. Molecular linkage of hantavirus pulmonary syndrome to the white-footed mouse, Peromyscus leucopus: genetic characterization of the M genome of New York virus. J Virol (1995) 69:8137–8141.[Abstract]
Hughes AL, Friedman R. Evolutionary diversification of protein-coding genes of hantaviruses. Mol Biol Evol (2000) 17:1558–1568.
Hutchinson KL, Rollin PE, Peters CJ. Pathogenesis of a North American hantavirus, Black Creek Canal virus, in experimentally infected Sigmodon hispidus. Am J Trop Med Hyg (1998) 59:58–65.[Abstract]
Jackson AP, Charleston MA. A cophylogenetic perspective of RNA-virus evolution. Mol Biol Evol (2004) 21:45–57.
Jenkins GM, Rambaut A, Pybus OG, Holmes EC. Rates of molecular evolution in RNA viruses: a quantitative phylogenetic analysis. J Mol Evol (2002) 54:156–165.[CrossRef][Web of Science][Medline]
Kuenzi AJ, Douglass RJ, Bond CW, Callsher CH, Mills JN. Long-term dynamics of Sin Nombre viral RNA and antibody in deer mice in Montana. J Wildl Dis (2005) 41:473–481.
Martin DP, Williamson C, Posada D. RDP2: recombination detection and analysis from sequence alignments. Bioinformatics (2005) 21:260–262.
Monroe MC, Morzunov SP, Johnson AM, Bowen MD, Artsob H, Yates T, Peters CJ, Rollin PE, Ksiazek TG, Nichol ST. Genetic diversity and distribution of Peromyscus-borne hantaviruses in North America. Emerg Infect Dis (1999) 5:75–86.[Web of Science][Medline]
Morzunov S, Rowe J, Ksiazek T, Peters C, St. Jeor SC, Nichol ST. Genetic analysis of the diversity and origin of hantaviruses in Peromyscus leucopus mice in North America. J Virol (1998) 72:57–64.
Nemirov K, Henttonen H, Vaheri A, Plyusnin A. Phylogenetic evidence for host switching in the evolution of hantaviruses carried by Apodemus mice. Virus Res (2002) 90:207–215.[CrossRef][Web of Science][Medline]
Padula PJ, Edelstein A, Miguel SDL, Lopez NM, Rossi CM, Rabinovich RD. Hantavirus pulmonary syndrome outbreak in Argentina: molecular evidence for person-to-person transmission of Andes virus. Virology (1998) 241:323–330.[CrossRef][Web of Science][Medline]
Page RDM. Temporal congruence revisited: comparison of mitochondrial DNA sequence divergence in cospeciating pocket gophers and their chewing lice. Syst Biol (1996) 45:151–167.
Peters CJ, Simpson GL, Levy H. Spectrum of hantavirus infection: hemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome. Annu Rev Med (1999) 50:531–545.[CrossRef][Web of Science][Medline]
Plyusnin A, Morzunov SP. Virus evolution and genetic diversity of hantaviruses and their rodent hosts. Curr Top Microbiol Immunol (2001) 256:47–75.[Web of Science][Medline]
Plyusnin A, Vapalahti O, Lehvaslaiho H, et al, (11 co-authors). Genetic variation of wild Puumala viruses within the serotype, local rodent population and individual animals. Virus Res (1995) 38:25–41.[CrossRef][Web of Science][Medline]
Plyusnin A, Vapalahti O, Vaheri A. Hantaviruses: genome structure, expression and evolution. J Gen Virol (1996) 77:2677–2687.
Posada D, Crandall KA. Modeltest: testing the model of DNA substitution. Bioinformatics (1998) 9:817–818.
Salemi M, Lewis M, Egan JF, Hall WW, Desmyter J, Vandamme A-M. Different population dynamics of human T cell lymphotropic virus type II in intravenous drug users compared with endemically infected tribes. Proc Natl Acad Sci USA (1999) 96:13253–13258.
Schmaljohn C. Bunyaviridae: the viruses and their replication. In: Fields virology—Fields BN, Knipe DM, Howley PM, eds. (1996) 3rd ed. Philadelphia (PA): Lippincott-Raven Publishers. 649–673.
Sironen T, Vaheri A, Plyusnin A. Molecular evolution of Puumala hantavirus. J Virol (2001) 75:11803–11810.
Vapalahti O, Lundkvist A, Fedorov V, et al, (14 co-authors). Isolation and characterization of a hantavirus from Lemmus sibiricus: evidence for host-switch during hantavirus evolution. J Virol (1999) 73:5586–5592.
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