Phylogenetic analysis of ORF5 and ORF7 of porcine reproductive and respiratory syndrome (PRRS) virus and the frequency of wild-type PRRS virus in México

Abstract

Porcine reproductive and respiratory syndrome (PRRS) is caused by a genetically diverse RNA virus and is an economically significant disease in the swine industry. In this study, a total of 8,126 serum samples were obtained from 275 technified and semi-technified farms belonging to 30 of the 32 states of Mexico and representative of the eight regions of the country. Anti-PRRSv antibodies against the PRRS vaccine and an isolated wild Mexican virus were tested by ELISA. Antibodies were found in 15%-49% of the tested sera, with 2.4%-9.8% against the vaccine and 7.7%-26% against the wild virus. The PRRSv virus was detected by RT-PCR in 77 of the 1,630 pooled samples tested, representing seven of the eight geographic regions into which the Mexican Republic is divided. The complete sequences of open reading frames 5 and 7 from 20 PRRSv-positive samples were determined. The analysis of the sequences together with the previously published sequences of historic strains revealed that all the strains belonged to the one, five and eight lineages of the PRRSV2. Striking differences, particularly in ORF5 and ORF7, were found between sequences of the strains and the reference virus, due to insertions and substitutions in positions that play key roles in the recognition, structure and function of the virus. Overall, these results established the magnitude of PRRS virus genetic diversity, and the most frequent virus strain that predominates in Mexico. The PRRSV2 is presented in the porcine population of Mexico; the circulating strains have important changes in ORF5 and ORF7, which probably explain the results obtained in the serological analysis of the wild virus and vaccine strains.

Analysis of ORF5 sequences of Porcine Reproductive and Respiratory Syndrome virus (PRRSV) circulating within swine farms in Costa Rica

“…The phylogenetic inferences from our study are consistent with previously published trees [ 19 , 39 , 41 ]. The three distinctive strains found in the samples of Costa Rica share common ancestors with USA and Mexican strains.…”

“…The three distinctive strains found in the samples of Costa Rica share common ancestors with USA and Mexican strains. A similar tendency is shown in Mexico [ 41 ] and is supported by common trade routes of breeders and semen. It is suggested that genetic similarity between the isolates is not necessarily correlated with the geographical distance.…”

“…ORF5 has about 600 nucleotides, shows great genetic diversity, and has a mutation rate of approximately 0.5-1% per year. Although whole-genome sequencing of the PRRSV may give a more complete picture in support of the molecular epidemiology, sequencing ORF5 provides sufficient information to conduct phylogenetic inferences [ 37 , 41 ].…”

An Outbreak of a Respiratory Disorder at a Russian Swine Farm Associated with the Co-Circulation of PRRSV1 and PRRSV2

“…A critical role of this element of the N protein in pathogenesis has been shown [ 23 ]. A similar insertion is known to be found in a Mexican field isolate DMZC144/2016 (GenBank ID MF352184.1) [ 24 ]. This might indicate that both Kem19NA and DMZC144/2016 have a nucleoprotein consisting of 124 amino acids in length.…”

Salud porcina: historia, retos y perspectivas

“…Actualmente en México, se han realizado estudios de caracterización antigénica y genética con las cepas que circulan en México, y se ha reportado que las cepas de PRRS presentan variaciones antigénicas y genéticas en una misma unidad de producción (72) . Diferentes grupos de investigadores se encuentran trabajando en el estudio de las regiones antigénicas del vPRRS (73) , con el objetivo de identificar cepas prototipos para la elaboración de herramientas de diagnóstico y vacunas, como posibles herramientas que coadyuven en la prevención y control en México.…”