Identification of a genetic variant of canine distemper virus from clinical cases in two vaccinated dogs in Mexico

Canine distemper virus (CDV) is a highly contagious viral pathogen of worldwide distribution that can cause lethal disease in dogs and other mammals. Genetic diversity is found among reference strains and isolates of CDV, mainly in the haemagglutinin protein (H), fusion protein (F) and nucleoprotein (N), and this may be associated with the increasing incidence of distemper in dogs. CDV was identified by RT-PCR in serum samples taken from two clinically diseased, previously vaccinated Mexican dogs. Subsequently, in both samples, a fragment of the CDV N gene was sequenced revealing a 100% identity between nucleotide sequences. However, the sequence obtained was different to that found in virus strains used in vaccines and in isolates reported elsewhere, but was closely related to A75/17, 1127/Gi95, and 2495/Gi95 sequences from USA and Germany, and clustered with 1127/Gi95 and 2495/Gi95 strains. The results suggest that a novel CDV lineage may be present in Mexico.     

Molecular characterization of the VP1 gene of a Mexican isolate of infectious pancreatic necrosis virus

The presence of infectious pancreatic necrosis virus (IPNV) in salmonids predominantly produces a high mortality rate in first-feeding fry. Genomic analysis of the vp2 gene sequence is most commonly used to determine the genetic diversity of IPNV isolates. Recently, information obtained from the vp1 gene allowed for efficient analysis of the genetic diversity of IPNV. In this study, the vp1 gene from a Mexican IPNV isolate was characterized and compared with IPNV isolates from Europe, North America, and Asia. The results indicate that the Mexican isolate is most closely related genetically to the 2310 strain from Spain.     

Genetic analysis of Mexican Criollo cattle populations

The objective of this study was to evaluate the genetic structure of Mexican Criollo cattle populations using microsatellite genetic markers. DNA samples were collected from 168 animals from four Mexican Criollo cattle populations, geographically isolated in remote areas of Sierra Madre Occidental (West Highlands). Also were included samples from two breeds with Iberian origin: the fighting bull (n = 24) and the milking central American Criollo (n = 24) and one Asiatic breed: Guzerat (n = 32). Genetic analysis consisted of the estimation of the genetic diversity in each population by the allele number and the average expected heterozygosity found in nine microsatellite loci. Furthermore, genetic relationships among the populations were defined by their genetic distances. Our data shows that Mexican cattle populations have a relatively high level of genetic diversity based either on the mean number of alleles (10.2-13.6) and on the expected heterozygosity (0.71-0.85). The degree of observed homozygosity within the Criollo populations was remarkable and probably caused by inbreeding (reduced effective population size) possibly due to reproductive structure within populations. Our data shows that considerable genetic differentiation has been occurred among the Criollo cattle populations in different regions of Mexico.     

Milk yield did not decrease in large herds of high-producing Holstein cows in semi-arid climate of Mexico

This study aimed to determine the trends in milk production, fertility, temperature-humidity index (THI), and herd size in dairy herds from the Laguna region in northern Mexico. Records of 16 dairy herds of Holstein cows from January 2002 to December 2016 were used. Milk production was categorized in low and high levels. Milk production and fertility were analyzed using generalized equation estimation procedures by a model of repeated measures that included the effect of year, month, and productive level, an interaction for month × productive level, and herd effect was nested in productive level. For THI, a generalized linear model that included the effects of year and month was used. Dairy herds with high levels of milk production yielded more milk than those with low levels (P?<?0.001). Milk production in 2002 and 2016 was 27.4?±?0.6 and 32.3?±?0.7 L/cow/day, respectively. Fertility fluctuated throughout the study. Dairy herds with high levels of milk production recorded higher fertility than those with low levels (P?<?0.001). From October to April, THI was <?70, whereas it was >?73 from May to September, indicating that cows were in heat stress (20 h/day). The median herd size was 995 and 2569 cows in 2002 and 2016, respectively. In conclusion, in large herds, milk production increased over the years of study, whereas fertility showed a wave cycle; nonetheless, when THI was >?73, both milk production and fertility decreased.

     

Genotyping of infectious pancreatic necrosis virus isolates from Mexico state

The infectious pancreatic necrosis virus (IPNV; genus Aquabirnavirus) affects salmon and trout, causing high mortality in first-feeding fry. The classification of this virus includes nine serotypes and seven genogroups. In Mexico, two different isolates were identified in 2000 and 2008, respectively. Both isolates were classified into genogroup I according to the RNA genome of this virus. As Mexico is importing rainbow trout Oncorhynchus mykiss eggs from different countries, the aim of this study was to genotype IPNV isolates obtained from four rainbow trout producer regions within the state of Mexico. We utilized a fragment of the VP2* (outer capsid protein) gene sequence of Mexican IPNV isolates as a molecular marker to determine the genogroup to which they belong. Although all Mexican IPNV isolates were grouped into genogroup I, we identified genetic diversity among these isolates, and 14 unique nucleotide sequence types were associated with the four producer regions in Mexico State.     

Genetic analysis of Mexican hairless pig populations.

The main Creole pig population in Mexico, the hairless Mexican pig, remains as an unimproved and endangered genetic resource. In order to learn more about the genetic characteristics of this pig population, we assessed the allele frequency of 10 microsatellite loci in 177 unrelated hairless pigs from seven regions at Mexico and in 111 pigs of four commercial breeds (Landrace, Large White, Hampshire, and Duroc). Genetic diversity in each population was estimated by the unbiased average heterozygosity and the allele number. Nei's standard genetic distances and a neighbor-joining dendrogram were used to reveal the genetic relationships among these populations. In this report, we present data showing that the level of the genetic diversity in Mexican hairless pigs is high compared with previous reports, and that they belong to a genetic lineage divergent from commercial breeds. Furthermore, Mexican hairless pigs seem to have developed several genetically distinct lines associated with their geographic location. We conclude that the Mexican Creole pig populations may be a reservoir of genetic diversity that is important to preserve and evaluate as a source of new alleles for the future improvement of commercial pig lines.     

Genotyping of Infectious Pancreatic Necrosis Virus Isolates from Mexico State

Abstract

The infectious pancreatic necrosis virus (IPNV; genus Aquabirnavirus) affects salmon and trout, causing high mortality in first-feeding fry. The classification of this virus includes nine serotypes and seven genogroups. In Mexico, two different isolates were identified in 2000 and 2008, respectively. Both isolates were classified into genogroup I according to the RNA genome of this virus. As Mexico is importing rainbow trout Oncorhynchus mykiss eggs from different countries, the aim of this study was to genotype IPNV isolates obtained from four rainbow trout producer regions within the state of Mexico. We utilized a fragment of the VP2* (outer capsid protein) gene sequence of Mexican IPNV isolates as a molecular marker to determine the genogroup to which they belong. Although all Mexican IPNV isolates were grouped into genogroup I, we identified genetic diversity among these isolates, and 14 unique nucleotide sequence types were associated with the four producer regions in Mexico State.

Received December 21, 2010; accepted July 27, 2011     

Histopathologic study of long-bone growth plates confirms the basset hound as an osteochondrodysplastic breed

Osteochondrodysplasias are caused by abnormal development and growth of cartilage and bone. These abnormalities have been reported in both humans and animals with dwarfism. The basset hound is considered a breed with a disproportionate prevalence of dwarfism, the cause of which is unknown. To determine the type of osteochondrodysplasia in this breed, we analyzed histologically the growth plates from the long bones of a basset hound and a Doberman pinscher, both 2 mo old. Tissue was fixed in 4% paraformaldehyde, embedded in paraffin, sectioned at 5 microm, stained with hematoxylin and eosin, and analyzed by light microscopy. Our results suggest that by this method the basset hound can be defined only as a breed having osteochondrodysplasia due to a primary cartilage problem in the growth plate.