Sensitivity of field isolates of Eimeria acervulina and E. maxima from three regions in Brazil to eight anticoccidial drugs.

Rotation with different active ingredients is among the most effective and recommended strategies to preserve the efficacy of anticoccidial drugs and reduce the emergence of resistance. Tools such as anticoccidial sensitivity tests (ASTs) are ideally used to make rational rotation programs and bring benefits to production. The objective of this study was to evaluate the sensitivity of E. acervulina (EA) and E. maxima (EM) from 3 different regions in Brazil, by using four ASTs. Feces samples weighing 6 to 7 kg were collected in the regions of São Paulo, Paraná, and Minas Gerais. Prevalent oocysts from feces were filtered, identified, and quantified to conduct 2 ASTs with EA and 2 with EM. The same experimental design was used in every AST (4 replicates per treatment, with 6 birds each, for a total of 240 birds). Treatment groups were a nonchallenged and nonmedicated control group (T1), a challenged and nonmedicated control group (T2), and the other groups challenged and treated with the following compounds: lasalocid (90 ppm - T3), maduramycin (6 ppm - T4), decoquinate (30 ppm - T5), nicarbazin+semduramicin (66 ppm - T6), monensin (110 ppm - T7), salinomycin (66 ppm - T8), narasin+nicarbazin (100 ppm - T9), and nicarbazin (125 ppm - T10). At the end of each AST (20 d), the percent change (delta value) between the treated group (T3 to T10) and the control group (T2) was calculated for the following variables: body weight gain, feed conversion ratio, lesion score, and an indicator of percentage of optimal anticoccidial activity (POAA) that included T2. Different sensitivity levels of EA and EM isolates could be identified. As a whole, drugs from T5 and T3 groups showed higher delta values when compared to other compounds, whereas the lowest sensitivity levels of these isolates were observed in groups T4 and T7. Despite some limiting factors, ASTs can be a good tool for strategic selection of anticoccidial drugs in order to maintain efficacy and extend the lifespan of these molecules.

Comparison of CVI and HVT vaccine strains replication in feather tips in different Marek´s disease vaccination programs / Comparação da replicação da estirpe vacinal CVI e HVT no folículo da pena em diferentes programas vacinais para a doença de Marek

Marek's disease is an important neoplastic disease in birds caused by a serotype 1 specific herpesvirus; it is controlled by vaccination. In commercial breeders and layers in Brazil, current vaccination programs use the combination of attenuated or non-pathogenic strains of the HVT virus (turkey herpesvirus - serotype 3) and CVI 988 (Rispens - serotype 1). The combination of serotype 3 and 1 it has been an important and effective control strategy through the vaccination of long-lived birds. In addition, more recently the recombinant rHVT strain (vectorized vaccines) has been used in some vaccine programs. This studys main objective was to compare CVI and HVT components replication in feather tips in three different Marek's disease (MD) immunoprophylactic programs (T01 program A, T02 program B and T03 program C). Quantification of these two vaccine strains was performed by real-time PCR in samples collected at the ages of 14, 21, and 28 days. At 14 days, mean of log[cvi] in program B was significantly higher than C (p<0.05). For mean of log[hvt], at 28 days, program B was significantly higher than A (p<0.05). For proportion of positives, at 14 days, program B had 2.7 times more risk to be positive in CVI than program C (p<0.001). At 21 days, program B had 1.7 times more risk to be positive in CVI than program C (p=0.005). For HVT, at 28 days, program B had 3.2 times more risk to be positive than program A (p=0,009). Results showed significant differences between the treatments evaluated. In general the conventional combination Mareks vaccine containing CVI+HVT (program B) showed higher replication rate and percentage of vaccine coverage than the programs with rHVT vector vaccines (program A and C).(AU)

A doença de Marek é uma importante doença neoplásica das aves causada por um herpesvírus específico do sorotipo 1 e seu controle se faz por vacinação. Em reprodutoras e poedeiras comerciais do Brasil, os programas de vacinação utilizam a combinação de estirpes atenuadas ou não patogênicas do vírus HVT (turkey herpesvirus - sorotipo 3) e CVI 988 (Rispens - sorotipo 1). A combinação do sorotipo 3 e 1 tem sido uma importante e efetiva estratégia de controle para aves de vida longa. Além disso, mais recentemente a fração rHVT recombinante (vacinas vetorizadas) vem sendo utilizada em alguns programas vacinais. O objetivo deste estudo foi comparar a replicação das frações CVI e HVT no folículo da pena em três programas imunoprofiláticos distintos (T01 programa A, T02 programa B e T03 programa C). A quantificação das duas estirpes vacinais foi realizada por PCR em tempo real nas amostras colhidas nas idades de 14, 21 e 28 dias. Aos 14 dias, em média, log[cvi] do programa B foi significativamente maior do que C (p<0.05). Aos 21 e 28 dias, a média do log[cvi] do programa C foi significativamente menor do que A e B (p<0.05). Para log[hvt], aos 28 dias, a média do programa B foi significativamente maior do que A (p<0.05). Para proporção de positivos, aos 14 dias, o programa B teve 2,7 vezes mais risco de ter positivos no CVI do que C (p<0.001). Aos 21 dias, o programa B teve 1,7 vezes mais risco de ter positivos no CVI do que C (p=0.005). Para HVT, aos 28 dias, o programa B teve 3,2 vezes mais risco de ter positivos do que A (p=0,009). Os resultados obtidos evidenciam diferenças significativas entre os tratamentos. De maneira geral a vacina convencional de Marek combinada com o CVI e HVT (programa B) apresentou maior taxa de replicação, velocidade e percentual de cobertura vacinal do que os programas compostos com vacinas vetorizadas com rHVT (programa A e C).(AU)

Comparison of CVI and HVT vaccine strains replication in feather tips in different Marek´s disease vaccination programs / Comparação da replicação da estirpe vacinal CVI e HVT no folículo da pena em diferentes programas vacinais para a doença de Marek

Marek's disease is an important neoplastic disease in birds caused by a serotype 1 specific herpesvirus; it is controlled by vaccination. In commercial breeders and layers in Brazil, current vaccination programs use the combination of attenuated or non-pathogenic strains of the HVT virus (turkey herpesvirus - serotype 3) and CVI 988 (Rispens - serotype 1). The combination of serotype 3 and 1 it has been an important and effective control strategy through the vaccination of long-lived birds. In addition, more recently the recombinant rHVT strain (vectorized vaccines) has been used in some vaccine programs. This study’s main objective was to compare CVI and HVT components’ replication in feather tips in three different Marek's disease (MD) immunoprophylactic programs (T01 – program A, T02 – program B and T03 – program C). Quantification of these two vaccine strains was performed by real-time PCR in samples collected at the ages of 14, 21, and 28 days. At 14 days, mean of log[cvi] in program B was significantly higher than C (p<0.05). For mean of log[hvt], at 28 days, program B was significantly higher than A (p<0.05). For proportion of positives, at 14 days, program B had 2.7 times more risk to be positive in CVI than program C (p<0.001). At 21 days, program B had 1.7 times more risk to be positive in CVI than program C (p=0.005). For HVT, at 28 days, program B had 3.2 times more risk to be positive than program A (p=0,009). Results showed significant differences between the treatments evaluated. In general the conventional combination Marek’s vaccine containing CVI+HVT (program B) showed higher replication rate and percentage of vaccine coverage than the programs with rHVT vector vaccines (program A and C).

A doença de Marek é uma importante doença neoplásica das aves causada por um herpesvírus específico do sorotipo 1 e seu controle se faz por vacinação. Em reprodutoras e poedeiras comerciais do Brasil, os programas de vacinação utilizam a combinação de estirpes atenuadas ou não patogênicas do vírus HVT (turkey herpesvirus - sorotipo 3) e CVI 988 (Rispens - sorotipo 1). A combinação do sorotipo 3 e 1 tem sido uma importante e efetiva estratégia de controle para aves de vida longa. Além disso, mais recentemente a fração rHVT recombinante (vacinas vetorizadas) vem sendo utilizada em alguns programas vacinais. O objetivo deste estudo foi comparar a replicação das frações CVI e HVT no folículo da pena em três programas imunoprofiláticos distintos (T01 – programa A, T02 – programa B e T03 – programa C). A quantificação das duas estirpes vacinais foi realizada por PCR em tempo real nas amostras colhidas nas idades de 14, 21 e 28 dias. Aos 14 dias, em média, log[cvi] do programa B foi significativamente maior do que C (p<0.05). Aos 21 e 28 dias, a média do log[cvi] do programa C foi significativamente menor do que A e B (p<0.05). Para log[hvt], aos 28 dias, a média do programa B foi significativamente maior do que A (p<0.05). Para proporção de positivos, aos 14 dias, o programa B teve 2,7 vezes mais risco de ter positivos no CVI do que C (p<0.001). Aos 21 dias, o programa B teve 1,7 vezes mais risco de ter positivos no CVI do que C (p=0.005). Para HVT, aos 28 dias, o programa B teve 3,2 vezes mais risco de ter positivos do que A (p=0,009). Os resultados obtidos evidenciam diferenças significativas entre os tratamentos. De maneira geral a vacina convencional de Marek combinada com o CVI e HVT (programa B) apresentou maior taxa de replicação, velocidade e percentual de cobertura vacinal do que os programas compostos com vacinas vetorizadas com rHVT (programa A e C).