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Table 6 Viral neutralization test results using PRRSV strains 3262 and 3267

From: Characterization of homologous and heterologous adaptive immune responses in porcine reproductive and respiratory syndrome virus infection

  Nº of responding pigs; mean titre (log2 ) and standard deviation Range of titres (log2 ) for positive pigs
  Strain used in the viral neutralization test
  3262 3267
  Days post-inoculation Days post-inoculation
Challenge group† 21 42 84 98 21 42 84 98
A + A 0/4 0/4 0/4 0/4 0/4 3/4* 4/4* 4/4*
(3262+3262) - - - - - 1.7 ± 0.6a 2.0 ± 0.8a 4.25 ± 1.0b
       (1–2) (1–3) (3–5)
A + B 0/4 0/4 0/4 0/4 0/4 2/4 2/4 4/4*
(3262+3267) - - - - - 1.0 ± 0.0a 2.0 ± 0.0a 5.3 ± 0.5b
       (1–1) (2–2) (5–6)
C1 + B 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2*
(C+3267) - - - - - - - 2.5 ± 0.5
         (2–3)
B + B 0/4 2/4 4/4‡ 4/4‡ 4/4‡ 4/4 4/4 4/4
(3267+3267) 0/4 1.0 ± 0.0 2.2 ± 1.5 2.8 ± 1.7 2.0 ± 0.8a 2.5 ± 1.0a 4.8 ± 1.0b 6.0 ± 0.8
  - (1–1) (1–4) (1–5) (1–3) (2–4) (4–6) (5–7)
B + A 0/3 0/3 3/3‡ 3/3‡ 1/3 3/3 3/3 3/3
(3267+3262)    2.0 ± 1.0 1.3 ± 0.6 1.0 ± 0.0 3.0 ± 1.0a 4.0 ± 1.0a 5.3 ± 0.6b
  - - (1–3) (1–2) (1–1) (2–4) (3–5) (5–6)
C2 + A 0/3 0/3 0/3 0/3 0/3 0/3 0/3 0/3
(C+3262) - - - - - - - -
  1. † Chronological sequence of strains used for inoculation is shown in parentheses.
  2. * The asterisk show statistical differences (p < 0.05) for the proportion of responding pigs using one or the other PRRSV strain.
  3. Superscript letters indicate statistical differences (p < 0.05; ¶ p = 0.08) in the average titres between different days using a given strain.
  4. ‡ The symbol indicates statistically significant differences for the proportion of responding pigs for similar groups between experiments (i.e. homologous A + A vs. homologous B + B) using the same strain.