Assessment of the hemagglutinating activity of the Porcine orthorubulavirus.

Blue eye disease (BED) in pigs is caused by Porcine orthorubulavirus (PRV) of the Paramyxoviridae family. It is an endemic disease in swine production in the central region of Mexico and causes nervous signs and high mortality in suckling pigs, pneumonia in growing pigs, orchitis in boars and mummification during gestation. PRV hemagglutinates most red blood cells (RBCs) of domestic species. For serological diagnosis, the hemagglutination inhibition test is used, and in this test, guinea pig, bovine and chicken RBCs have been commonly used. In this investigation, hemagglutination with PRV was evaluated using the RBCs of seven domestic species (chicken, bovine, horse, pig, dog, guinea pig and rabbit). In the hemagglutination test, the following parameters were evaluated: temperature (25 °C and 37 °C), bottoms of the wells (V and U), erythrocyte concentration (0.5%, 0.75%, and 1%), and reading time (15, 30, 45, 60 and 90 min). Significant differences (P < 0.001) were found in most of the evaluated treatments. The best hemagglutination results were obtained with chicken, bovine and horse RBCs. The hemagglutination titer is higher (2 dilutions) when using chicken RBCs than when using bovine or horse RBCs. If chicken RBCs are used in the inhibition of hemagglutination, the test will be more sensitive, while it is more specific when bovine or horse RBCs are used. The hemagglutination readings are imprecise when using RBCs from dogs, pigs, guinea pigs and rabbits. RBCs from these species should not be used for the diagnosis or investigation of PRV.

Genetic improvement of Pacific white shrimp [Penaeus (Litopenaeus) vannamei]: perspectives for genomic selection.

The uses of breeding programs for the Pacific white shrimp [Penaeus (Litopenaeus) vannamei] based on mixed linear models with pedigreed data are described. The application of these classic breeding methods yielded continuous progress of great value to increase the profitability of the shrimp industry in several countries. Recent advances in such areas as genomics in shrimp will allow for the development of new breeding programs in the near future that will increase genetic progress. In particular, these novel techniques may help increase disease resistance to specific emerging diseases, which is today a very important component of shrimp breeding programs. Thanks to increased selection accuracy, simulated genetic advance using genomic selection for survival to a disease challenge was up to 2.6 times that of phenotypic sib selection.

Decline of genetic variability in a captive population of Pacific white shrimp Penaeus (Litopenaeus) vannamei using microsatellite and pedigree information

Background: The objective of this study was to estimate the decline of genetic variability and the changes in effective population size in three shrimp populations. One was a wild population collected at several points in the Mexican Pacific Ocean. The other two populations were different generations (7 and 9) from a captive population selected for growth and survival. Microsatellite markers and pedigree were both used to assess genetic variability and effective population size. Results: Using 26 loci, both captive populations showed a decline in the expected heterozygosity (20%) and allelic diversity indices (48 to 91%) compared to the wild population (P < 0.05). The studied captive populations did not differ significantly from each other regarding their expected heterozygosity or allelic diversity indices (P > 0.05). Effective population size estimates based on microsatellites declined from 48.2 to 64.0% in cultured populations (P < 0.05) compared to the wild population. Conclusions: An important decline of genetic variability in the cultured selected population due to domestication, and evidence of a further smaller decline in effective population size across generations in the selected population were observed when analyzing pedigree (41%) and microsatellite data (37%). Pedigree keeping is required to prevent the decline of effective population size and maintain genetic variability in shrimp breeding programs, while microsatellites are useful to assess effective population size changes at the population level.