Evaluation of the Replication, Pathogenicity, and Immunogenicity of Avian Paramyxovirus (APMV) Serotypes 2, 3, 4, 5, 7, and 9 in Rhesus Macaques

Khattar, Sunil K.; Nayak, Baibaswata; Kim, Shin-Hee; Xiao, Sa; Samal, Sweety; Paldurai, Anandan; Buchholz, Ursula J.; Collins, Peter L.; Samal, Siba K.

Serum samples of the rhesus macaques infected with the various APMV strains were collected on days 0, 21 and 28 dpi. Serotypespecific serum antibody titers were determined by a modified HI assay using chicken erythrocytes, except in the case of APMV-5, in which case titers were determined by an NI assay in Vero cells (Table 4 ). All the animals were confirmed to be seronegative for APMV-specific antibodies on day 0. Each of APMV serotypes induced a serum antibody response. However, the magnitude of the response varied. On day 21, the highest mean HI antibody titers were observed in rhesus macaques immunized wt APMV-2 (7.00 log 2 6 1.4). Moderate mean HI antibody titers were observed with wt APMV-3 (5.860.5), wt APMV-7 (5.360.5), rAPMV-7/Fcs-5B (4.560.6) and wt APMV-9 (4.5060.6), and the lowest mean HI antibody titers were observed with rAPMV-2 (type 1 Africa) (3.360.5) and wt APMV-5 (2.561.7). In case of wt rAPMV-4 and rAPMV-4/Fc-BC, only two of the four animals had serum HI antibody responses. The mean HI antibody titer values determined on day 28 were similar to day 21 values.