U43686); GTOV strains VAV-623, VAV-952, and AV 97021119 (Table 1); PIRV strain VAV-488 (GenBank accession no.
Antibody titers <20 were considered 10 in comparisons of antibody titers to GTOV strain INH-95551 and PIRV strain VAV-488 in individual blood samples.
The analyses of the ELISA data indicated that the arenaviruses isolated from Alston's cotton rat FHV-4149 and the short-tailed cane mice are strains of GTOV and that the arenaviruses isolated from the Alston's cotton rats other than FHV-4149 are strains of PIRV. The results of the neighbor-joining analysis of N protein gene sequence data (Figure) were 100% concordant with the serologic identities of the 21 viruses selected for genetic characterization, GTOV strain AV 97021119, and PIRV strain AV 97021016.
Similarly, nucleotide sequence nonidentity between the PIRV strains from 1994 (i.e., VAV-628 and VAV-956) was 5.2%, nucleotide sequence nonidentities among AV 97021016 and the 9 other PIRV strains from 1997 ranged from 0 to 6.3%, and nucleotide sequence nonidentities between the PIRV strains from 1994 and the 10 PIRV strains from 1997 ranged from 1.0% to 6.3%.
Antibody (IgG) against GTOV or PIRV was found in 11 (37.9%) of the 29 culture-positive cane mice, 2 (5.7%) of the 35 culture-negative cane mice, 1 (2.7%) of the 37 culture-positive cotton rats, none of the 20 culture-negative cotton rats, and none of the 7 pygmy rice rats (Table 4).
The end-point antibody titers to GTOV in the antibody-positive cane mice ranged from 40 to 160, none of the cane mice were antibody positive to PIRV, and the end-point antibody titers to GTOV and PIRV in the antibody-positive Alston's cotton rat were 40 and [greater than or equal to] 640, respectively.
Seventeen (65.4%) of the 26 Alston's cotton rats in size classes I and II, 19 (61.3%) of the 31 Alston's cotton rats in size classes III and IV, 9 (50.0%) of the 18 male Alston's cotton rats in size classes III and IV, and 10 (76.9%) of the 13 female Alston's cotton rats in size classes III and IV were infected with PIRV (Table 2).
Specifically, the short-tailed cane mouse is the principal host of GTOV, and Alston's cotton rat is the principal host of PIRV. Examples of GTOV infection in rodents other than the short-tailed cane mouse are limited to the isolation of AV 97021116 from Alston's cotton rat FHV-4149 and the isolation of GTOV from a pygmy rice rat (Oligoryzomys sp.) and 4 Alston's cotton rats captured at localities in Venezuela other than Hato Maporal (11).
Yet none of the 57 short-tailed cane mice captured on A or B were infected with PIRV, and only 1 of the 55 Alston's cotton rats captured on A or B was infected with GTOV.
Together, the high prevalence of PIRV infection in the Alston's cotton rats in size class 1 and the lack of an association between prevalence of infection and size class in the Alston's cotton rats suggest that most cotton rats become infected with PIRV at an early age, perhaps in utero or immediately postpartum.
GTOV virus is presumed to be the only agent of VHF; however, the majority of the arenaviruses isolated from VHF patients during September 1989 through December 2006 were identified as strains of GTOV solely on the basis of the results of an IFAT in which extensive cross-reactivity between PIRV and GTOV is possible (5).