3. The Genetic Diversity of PRSV
Knowledge of the genetic diversity of PRSV is important for
effective evidence-based disease management. The genetic
diversity of PRSV was observed in different regions of the
world [34]. PRSV isolates and the sequence for PRSV CP
genes have been presented in Table 1. Sequence diversity
among isolates of the virus and their distribution are important
for establishing virus origin, development, dispersion,
and disease etiology, in the pursuit of effective virus disease
management. There is little sequence variation among the
CP genes of PRSV isolates from the USA and Australia [35,
36]. On the other hand, there is greater sequence variation
amongst the CP genes of PRSV isolates from India [37]
and Mexico [38]. The diversity at amino acid and nucleic
acid levels was highest among the Asian population of
PRSV isolates [37]. The PRSV isolates from India differed
from the PRSV isolates from other countries. Bateson et al.
[39] reported that the origin of PRSV was South Asia and
found a greater diversity in PRSV isolates from India. The
differences in PRSV were observed due to differences in the
CP gene length [37].The highest diversity of PRSV nucleotide
sequences was found in the CP and HC-Pro genes collected
from India [40]. PRSV might have been transported from
The Scientific World Journal 3
Proteinase
active sites
Proteinase
active sites
Proteinase
active sites
Nucleotide binding sites
Cysteine
cluster
NIa VPg domain NIa proteinase
domain
Prolymerase
active sites
1 548 1005 1402 2094 2521 3038 3344
456–465
497–500
519–523
573–604
888–891
963
1486–1494
2094–2282 2283–2520
2763–2769
2826–2842
2869–2908
2327, 2362,
2431
21K 27K
P1 (63K) HC-Pro (52K) P3 (46K)
2037 6K
CI (72K) NIa (48K) Nib (59K) CP (35K)
Figure 1: The map of the PRSV polyprotein. Specific motifs are indicated, solid bars indicate cleavage sites in the polyprotein, and the dashed
line indicates the potential internal cleavage site of the NIa protein.
India to America in the early 18th century and spread in 19th
and 20th centuries [40]. Variation in the CP gene sequences
of PRSV was observed in different parts of the world [35].The
genetic diversity of PRSV depends on geographical location.
For example, the transgenic papaya incorporating CP gene
(HA 5-1) isolated from USA showed resistance to PRSV
infection by the severe USA isolate (HA) but did not show
resistance against infection by the Australian andThai isolates
of PRSV [34].