Efficacy evaluation of two commercial modified-live virus vaccines against a novel recombinant type 2 porcine reproductive and respiratory syndrome virus.

NADC30-like porcine reproductive and respiratory syndrome virus (PRRSV) causing clinical disease outbreaks has been recently reported in China. The recombination occurring among PRRSV strains could lead to the emergence of novel and more virulent viruses. In our previous study, a novel recombinant type 2 PRRSV (TJnh1501) between NADC30-like and modified-live virus (MLV)-like derived from the Chinese highly pathogenic PRRSV was shown to have higher pathogenicity than NADC30-like PRRSV. It remains unknown whether the emergence of the novel recombinant PRRSV strain can lead to variable protection efficacy of the MLV vaccines. In this paper, two typical commercial MLV vaccines were used to evaluate their efficacy to block TJnh1501 infection and onset of clinical symptoms. Our results showed that both MLV vaccines could shorten the period of fever and reduce viral loads in sera, but were not able to reduce the clinical signs and lung lesions indicating that the two commercial MLV vaccines provide limited cross-protection efficacy against the novel recombinant type 2 PRRSV infection. This study gives valuable suggestions for the use of MLV vaccines to control PRRSV infection in the field.

Acetylation of H4K12 in porcine oocytes during in vitro aging: potential role of ooplasmic reactive oxygen species.

Deterioration in the quality of mammalian mature oocytes during metaphase-II (M-II) arrest is called "oocyte aging". Although histone acetylation may affect the progression of aging in murine oocytes, the mechanism is unknown. The objective was to determine the role of ooplasmic reactive oxygen species (ROS) in acetylation of histone H4 at lysine 12 (acH4K12) in porcine aged oocytes in vitro. Based on immunostaining with a specific antibody, acetylation of H4K12 in porcine oocytes increased during in vitro aging, which coincided with changing patterns of ooplasmic ROS content. Furthermore, both hydrogen peroxide (H(2)O(2)), and the mitochondrial membrane potential disrupter, carbonyl cyanide 3-chlorophenylhydrazone (CCCP), which can moderately elevate oocyte ROS content, significantly increased acetylation levels of H4K12 in porcine oocytes. It was noteworthy that acetylation in the CCCP group was decreased when ROS was counteracted by cysteine, a common antioxidant. In addition, the intracellular mRNA abundance of acetyltransferase gene HAT1 in aged and H(2)O(2) treated oocytes was higher than in M-II phase oocytes, suggesting that HAT1 was involved in this reaction. After parthenogenetic activation, a lower proportion of oocytes developed to the blastocyst stage after CCCP or H(2)O(2) treatment when compared with M-II phase oocytes (20 and 0% for CCCP and H(2)O(2) groups, respectively, versus 42% for the M-II group, P < 0.05). In conclusion, elevated levels of H4K12 acetylation were attributed to increased ooplasmic ROS content during porcine oocyte aging in vitro.

Abnormal changes in mitochondria, lipid droplets, ATP and glutathione content, and Ca(2+) release after electro-activation contribute to poor developmental competence of porcine oocyte during in vitro ageing.

The present study aims to investigate major changes in porcine oocytes during ageing in vitro. After the oocytes were cultured for 44, 56, 68 and 80 h, changes to porcine oocytes in ultrastructure, mitochondrial distribution, glutathione (GSH) and ATP content, Ca(2+) release patterns and developmental competence after electro-activation were observed. Mitochondria were evenly distributed in oocytes at 44 h, aggregated in clusters or in peripheral cytoplasm at 68 h and dimly dispersed throughout ooplasm at 80 h. Mitochondrial shape during ageing was also observed by transmission electron microscopy (TEM) at the same time intervals. Most mitochondria were spherical at 44 h, and became elongated when the culture time was extended to 68 h and 80 h. Moreover, mitochondrial clustering became increasingly loose from 56 h. Lipid droplets in oocytes appeared prominent and electron-dense at 44 h, but electron density was lost at 56 h. Lipid droplets were solidified as of 68 h. There was an age-dependent decrease in ATP content per oocyte. Glutathione content per oocyte decreased significantly and remained lower after 56 h. Amplitudes of [Ca(2+)] rise decreased dramatically following 56 h, and the time required for [Ca(2+)] to plateau became shorter after electro-activation with prolonged culture time. Cleavage and blastocyst rates of aged oocytes progressively decreased, while the fragmentation rate gradually increased after electro-activation. It is concluded that abnormal changes in mitochondria, lipid droplets, Ca(2+) release after electro-activation, and ATP and GSH content in oocytes during ageing may result in poor developmental competence of parthenotes.

Effects of SOF and CR1 media on developmental competence and cell apoptosis of ovine in vitro fertilization embryos.

The present study was to investigate effects of synthetic oviductal fluid (SOF) and Charles Rosenkrans medium (CR1) culture systems on developmental competence and cell apoptosis of ovine in vitro fertilization (IVF) embryos. Ovine presumptive IVF zygotes were cultured in the following six media: (1) SOF supplemented with amino acids (SOFaa) and 8 mg/ml bovine serum albumin (BSA) for 9 days (SOFaaBSA); (2) SOFaa supplemented with 10% fetal bovine serum (FBS) for 9 days (SOFaaFBS); (3) SOFaaBSA for first 3 days and then SOFaaFBS for later 6 days (SOFaaBSA-FBS); (4) CR1 supplemented with amino acids (CR1aa) and 8 mg/ml BSA for 9 days (CR1aaBSA); (5) CR1aa supplemented with 10% FBS for 9 days (CR1aaFBS); (6) CR1aaBSA for first 3 days and then CR1aaFBS for later 6 days (CR1aaBSA-FBS). The rates of blastocyst and hatched blastocyst in group 1, group 3 and group 6 were not different (P>0.05), but were greater than in other three groups (P<0.05). In SOF and CR1 cultural system, SOFaaBSA and CR1aaBSA-FBS provided the highest blastocyst rates respectively. Both numbers of total cell and trophectoderm (TE) in expanded or hatched blastocyst from SOFaaBSA were significantly higher than CR1aaBSA-FBS (P<0.05). However, the inner cell mass (ICM) cell number and ratio of ICM to TE cell in expanded or hatched blastocysts were not different between two groups (P>0.05). The apoptotic signals were firstly observed at 8-cell stage in two groups and became stronger and stronger with the development of embryos. Rates of embryos with apoptotic signals in group 6 at morula or blastocyst were greater than in group 1 (P<0.05). The apoptotic nuclei numbers of morula or blastocyst in group 6 were also significantly higher than group 1 (P<0.05). It is concluded that CR1aaBSA-FBS can support in vitro development of ovine IVF embryos, but SOFaaBSA is more suitable.