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Determination of the Effective Dose of the Live Mycoplasma synoviae Vaccine, Vaxsafe MS (Strain MS-H) by Protection against Experimental Challenge

Jillian F. Jones, Kevin G. Whithear, Peter C. Scott and Amir H. Noormohammadi
Avian Diseases
Vol. 50, No. 1 (Mar., 2006), pp. 88-91
Stable URL: http://www.jstor.org/stable/4099136
Page Count: 4
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Determination of the Effective Dose of the Live Mycoplasma synoviae Vaccine, Vaxsafe MS (Strain MS-H) by Protection against Experimental Challenge
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Abstract

The minimum effective dose of the Mycoplasma synoviae-W (MS-H) vaccine was determined through protection against experimental challenge. Chickens were vaccinated by eyedrop with the following doses of a vaccine: 1.2 × 105, $2.4 \times 10^5$, $4.8 \times 10^5$, $9.6 \times 10^5$, $1.92 \times 10^6$, and $3.84 \times 10^6$ color change units (CCU), then challenged 6 wk after vaccination. Rapid serum agglutination results indicated that 100% of birds receiving an MS-H dose of $\geq 4.8 \times 10^5$ CCU had antibodies to MS and enzyme-linked immunosorbent assay results showed that 60% of birds receiving a dose of $4.8 \times 10^5$ or $9.6 \times 10^5$ CCU and 100% of birds receiving a dose of $1.92 \times 10^6$ or $3.84 \times 10^6$ had antibodies to MS. At postmortem after challenge, the following parameters were significantly lower in birds vaccinated with an MS-H dose of $\geq 4.8 \times 10^5$ CCU: air sac (AS) lesion severity; incidence of AS lesions; mucosal thicknesses in the upper trachea, middle trachea, and lower trachea (LT); and MS colonization of the LT and AS. It was concluded that an MS-H dose of $4.8 \times 10^5$ CCU was sufficient to elicit an antibody response in birds, prevent MS colonization in the LT and AS, and protect against AS lesions caused by an experimental MS and infectious bronchitis virus challenge. /// Se $determin\acute{o}$ la dosis $m\acute{i}nima$ efectiva de la vacuna Micoplasma synoviae-H (MS-H) mediante la $protecci\acute{o}n$ contra el $desaf\acute{i}o$ experimental. Las aves fueron vacunadas por $v\acute{i}a$ ocular empleando las siguientes dosis de vacuna: 1.2 × 105, $2.4 \times 10^5$, $4.8 \times 10^5$, $9.6 \times 10^5$, $1.92 \times 10^6$ y $3.84 \times 10^6$ unidades de cambio de color y fueron desafiadas a las 6 semanas posteriores a la $vacunaci\acute{o}n$. Los resultados de la prueba $r\acute{a}pida$ de $aglutinaci\acute{o}n$ del suero indicaron que el 100% de las aves que recibieron una dosis de vacuna MS-H mayor o igual a $4.8 \times 10^5$ unidades de cambio de color, mostraron anticuerpos contra el M. synoviae. Los resultados de la prueba de inmunoensayo con enzimas asociadas mostraron que el 60% de las aves que recibieron una dosis de vacuna de $4.8 \times 10^5$ o $9.6 \times 10^5$ unidades de cambio de color, y el 100% de las aves que recibieron una dosis de vacuna de $1.92 \times 10^6$ o $3.84 \times 10^6$, $ten\acute{i}an$ anticuerpos contra M. synoviae. Al examen post-mortem posterior al $desaf\acute{i}o$, los siguientes $par\acute{a}metros$ fueron significativamente menores en las aves vacunadas con una dosis de MS-H mayor o igual a $4.8 \times 10^5$ unidades de cambio de color: severidad e incidencia de las lesiones de los sacos $a\acute{e}reos$, grosor de la mucosa de la porción superior, media e inferior de la $tr\acute{a}quea$ y la $colonizaci\acute{o}n$ de M. synoviae en la porción inferior de la $tr\acute{a}quea$ y en los sacos $a\acute{e}reos$. Se concluye que una dosis de vacuna MS-H de $4.8 \times 10^5$ unidades de cambio de color fue suficiente para estimular una respuesta de anticuerpos en las aves, prevenir la $colonizaci\acute{o}n$ de M. synoviae en la porción inferior de la $tr\acute{a}quea$ y los sacos $a\acute{e}reos$, y proteger contra las lesiones de los sacos $a\acute{e}reos$ ocasionadas por un $desaf\acute{i}o$ experimental de M. synoviae y del virus de bronquitis infecciosa.

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