Parvovirus B19

From MicrobeWiki, the student-edited microbiology resource

Background

The life cycle of Canine Parvovirus. Photo credit: [1]

By Grace Potter

Parvovirus B19 is the only member of the Parvoviridae family that has been found to infect human hosts.[1] It was discovered in 1974, when a research group looking at hepatitis B surface antigens found a serum sample with unexpected results.[1] Another lab in Japan described a similar virus in 1979 that they called "Nakatami".[1] When compared, the two were found to be identical.[1] In 1985 this virus was officially recognized as a member of the Parvoviridae family due to its similarities in genome size and density.[1]

Infection by Parvovirus B19 (Parvo B19V) causes many diseases, including "fifth disease" in children, aplastic crisis for people with hemolytic anemia, anemia in immunocompromised patients, acute or chronic arthropathy in adults, and fetal hydrops in pregnant women.[2][3] Changes in the genome are potentially responsible for the wide variation of clinical presentations associated with B19V infection.[2]

Parvoviruses are classified in reference to what type of host they are capable of infecting and how they reproduce.[1] Those capable of infecting vertebrate hosts are referred to as "Parvovirinae" and are further subdivided by reproduction processes.[1] "Parvovirus" refers to members of the Parvoviridae family that reproduce autonomously, but there are also members of this family seen reproducing with a helper virus, "Dependovirus", and preferentially in erythroid cells, "Erythrovirus".[1] Parvovirus B19 has recently been found to exhibit extreme specificity for human erythroid progenitor cells, and has therefore been classified as an "erythrovirus".[4][1]

Genome Structure

The Parvovirus genome is a single strand of DNA with 5,596 nucleotides, 4,830 of which are coding regions.[1] This region contains 2 large open reading frames.[1] One large non-structural protein is coded by one open reading frame, NS1, and the second reading frame codes for 2 capsid proteins, VP1 and VP2.[1] The sequences of B19V isolates do not exhibit much genetic variation with NS1 showing incredibly high conservation, and 2-3% divergence in VP1 and VP2 regions.[1] When examining isolates from patients with chronic infection due to B19V, there is a much higher degree of variation at DNA and protein levels.[3]

There are now 3 distinct genotypes recognized as Parvovirus B19 including: (1) all prototype B19V isolates, (2) A6 and LaLi isolates, and (3) V9 and related isolates.[2] These variations in the genome are potentially responsible for the variety of host responses to infection.[2] In a study on 3 isolates of the 3 genotypes, the A6 isolate did not produce R5, R7, and R9 mRNAs, which are important in the production of VP1 and VP2 as coordinating mRNAs.[2] There was also an increase in sequence divergence between the 3 isolates. They found that B19V NS1-V9 and B19V NS1-A6 diverge by 13% from B19V NS1, but only diverge by 6% in protein structure.[2]

The V9 (A) and A6 (B) genomes are depicted with transcriptional landmarks. These include promoters (ie. P6), splice donors (D), and splice acceptors (A), as well as the ORFs encoded and their predicted protein sizes in kDa. Photo credit: [2]


[5]

[6]

Morphology of B19V and Viral Proteins

Parvoviruses are among the smallest DNA containing viruses that are capable of infecting mammal hosts.

B19 does not require helper virus to replicate, but it only replicates in erythroid cells… it has recently been re-classed as an erythrovirus and is the only one of its type in that category Virion = 2 proteins and single linear strand of DNA Capsid = icosahedral symmetry, 60 copies of capsomer, both positive and negative strand of DNA packaged Has no spikes on capsid surface B19 is extremely resistant to physical inactivation (small amount of DNA, gram positive (?) Inactivation by formalin, beta propiolactone, and gamma irradiation Capsid structure: made up of VP1 and VP2 VP2 is majority of capsid (96%), encoded from 3125 to 4786 VP1 is minor capsid protein, 2444 to 4786, identical to VP2 + 227 amino acids (VP1 unique region)

Section 3

Include some current research, with at least one figure showing data.

Section 4

Conclusion

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 Heegaard, E.D. and Brown, K.E. "Human Parvovirus B19." 2002. Clinical Microbiology Review 15(3):485-505.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 Chen, Z., Guan, W., Cheng, F., Chen, A.Y., and Qiu, J. "Molecular characterization of human parvovirus B19 genotypes 2 and 3" 2009. Virology, 394(2), 276-285.
  3. ↑ 3.0 3.1 Hemauer, A., von Poblotzki, A., Gigler, A., Cassinotti, P., Siegl, G., Wolf, H., and Modrow, S. "Sequence variability among different parvovirus B19 isolates" 1996. Journal of General Virology, 77(8), 1781-1785.
  4. ↑ Rinkūnaitė, I., Šimoliūnas, E., Bironaitė, D., Rutkienė, R., Bukelskienė, V., Meškys, R., and Bogomolovas, J. "The Effect of a Unique Region of Parvovirus B19 Capsid Protein VP1 on Endothelial Cells" 2021. Biomolecules, 11(4), 606.
  5. ↑ Jalali, Sedigheh, Farhardi, Ali, Dehbidi, G.R., Farjadian, Shirin, Sharifzadeh, Sedigheh, Ranjbaran, Reza, Seyyedi, Noorossadat, Namdari, Sepide and Behzad-Behbahani, Abbas. "The Pathogenic Aspects of Human Parvovirus B19 NS1 Protein in Chronic and Inflammatory Diseases" 2022. Interdisciplinary Perspectives on Infectious Diseases.
  6. ↑ Ros, Carlos, Bieri, Jan, and Leisi, Remo. "The VP1u of Human Parvovirus B19: A Multifunctional Capsid Protein with Biotechnological Applications" 2020. Viruses, 12(12), 1463.



Authored for BIOL 238 Microbiology, taught by Joan Slonczewski,at Kenyon College,2024

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