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Table 2 Level of temperature sensitivity of replication of rHPIV1 mutants in vitro.

From: Attenuation and efficacy of human parainfluenza virus type 1 (HPIV1) vaccine candidates containing stabilized mutations in the P/C and L genes

   

Mean reduction (log10) in virus titer ± S.E. at the indicated temperature compared to 32°Cc

 

Virusa

Virus titer ± S.E. at 32°Cb

35°C

36°C

37°C

38°C

39°C

40°C

Shut-off (°C)d

1

HPIV1 wt

7.7 ± 0.1

0.1 ± 0.1

0.1 ± 0.1

0.2 ± 0.1

0.7 ± 0.1

1.3 ± 0.1

3.0 ± 0.3

-

2e

rHPIV1-CR84G

9.2 ± 0.4

0.4 ± 0.2

0.4 ± 0.6

0.8 ± 0.5

0.3 ± 0.4

1.8 ± 0.6

4.5 ± 0.9

-

3e

rHPIV1-CR84GHNT553A

7.8 ± 0.1

-0.3 ± 0.2

-0.3 ± 0.2

-0.2 ± 0.2

0.1 ± 0.2

0.7 ± 0.2

2.5 ± 0.6

-

4e

rHPIV1-CΔ170

7.9 ± 0.3

0.2 ± 0.2

0.7 ± 0.8

0.5 ± 0.2

1.0 ± 0.3

2.6 ± 0.7

4.5 ± 1.0

-

5

rHPIV1-LY942A

8.0 ± 0.1

0.2 ± 0.3

1.2 ± 0.3

2.6 ± 1.1 c,d

6.4 ± 0.4

≥6.8 f

≥6.8

37°C

6e

rHPIV1-CR84GHNT553ALY942A

7.4 ± 0.2

0.4 ± 0.4

0.5 ± 0.4

2.3 ± 0.4

4.0 ± 0.6

6.0 ± 0.4

≥6.4

37°C

7

rHPIV1-CR84GLΔ1710–11

7.5 ± 0.7

0.8 ± 0.7

3.0 ± 0.6

4.8 ± 0.2

≥6.3

≥6.3

≥6.3

36°C

8

rHPIV1-CR84G/Δ170HNT553ALY942A

6.3 ± 0.1

0.3 ± 0.2

0.9 ± 0.6

2.0 ± 0.3

4.9 ± 0.2

≥5.1

≥5.1

38°C

9

rHPIV1-CR84G/Δ170HNT553ALΔ1710–11

6.4 ± 0.3

2.6 ± 0.6

4.0 ± 0.4

≥5.2

≥5.2

≥5.2

≥5.2

35°C

  1. a Data are the mean of three to sixteen experiments.
  2. b Viruses were titrated on LLC-MK2 cells at either permissive (32°C) or potentially restrictive (35°C – 40°C) temperatures for 7 days and virus titers are expressed as the mean ± standard error (S.E.). The limit of detection was 1.2 log10 TCID50/ml.
  3. c Values in bold indicate restricted replication, where the mean log10 reduction in virus titer at the indicated temperature vs 32°C was 2.0 log10 or greater than the difference in titer of HPIV1 wt at the same temperature vs 32°C. A virus is designated ts if restricted replication at 35°C–40°C is observed.
  4. d Underlined values indicate viral shut-off temperature, the lowest temperature at which restricted replication is observed.
  5. e These data have been previously published [13] [15] [16] and are included here for the purposes of comparison.
  6. f The symbol "≥" indicates that virus titers were at the limit of detection and therefore the reduction in virus titer versus 32°C is greater than or equal to the indicated value. There is no S.E. value for viruses at the limit of detection.
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Virology Journal

ISSN: 1743-422X