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This report describes the first prevalence of antibodies and experimental inoculation of suspected samples of porcine reproductive and respiratory syndrome virus (PRRSV) from ELISA positive pigs from swine herds in Brazil. Based on the hypothesis that this agent is present in swine herds worldwide, the objective of this work was to establish a diagnostic methodology and to investigate the occurrence of PRRSV in Brazilian swine herds. Fifty-four swine herds, the total number which imported genetic material (live pigs or swine semen) from countries where PRRS was endemic from 1990 to December 2000, from eight Brazilian States all included in this study. The sampling used was such as to detect a prevalence of infection of 5%, with a confidence level of 95%. A total of 3785 serum samples were tested for PRRSV antibodies by ELISA. Following the ELISA test, which was performed with two different commercial kits, all serum positive pigs were retested, examined and additional materials were collected. Viral isolation in permissive tissue culture cells and swine bioassays were performed. Additionally, reverse transcriptase polymerase chain reaction (RT-PCR) and nested RT-PCR were also performed. We could not demonstrate the presence of PRRSV or RNA of PRRSV by viral isolation or RT-PCR (or nested RT-PCR), respectively in all of the analyzed samples. Furthermore, the pigs inoculated with PRRSV suspicion samples did not seroconvert nor produce characteristic PRRS lesions in the swine bioassay. Thus, our results indicate no evidence of PRRSV in the samples analyzed from swine herds in this study.

Porcine reproductive and respiratory syndrome (PRRS) is a viral disease characterized by reproductive impairment or failure in breeding animals, and a respiratory disease in pigs of any age. Brazil is the fourth largest pork producer and exporter globally, and PRRS virus (PRRSV) infection has never been reported in the country. This study aimed to investigate the status of porcine biological samples from commercial swine herds, quarantined imported boars, wild boars and feral pigs to update PRRS information in Brazil. A total of 14,382 samples were collected from 2008 to 2020, including sera (n = 12,841), plasma (n = 1,000) and oral fluids (n = 541), comprehending 137 herds and free‐living pigs in eight Brazilian states. One out of 1,000 (0.1%) plasma and 15 out of 12,841 (0.11%) serum samples tested positive for PRRSV antibodies through ELISA. Upon ELISA retesting, only the plasma sample, from one 8‐day‐old piglet remained positive. All sixteen previously PRRSV antibody‐positive samples were tested through RT‐PCR and found to be negative. The presence of false‐positive or singleton reactors are quite expected. Thus, the use of different/alternative diagnostic tests is indicated for an efficient PRRSV detection. Taken together, our findings demonstrated no conclusive evidence of PRRSV infection in the tested pigs, highlighting the importance to reinforce the surveillance program to prevent the introduction and eventual dissemination of PRRSV in Brazil. [ABSTRACT FROM AUTHOR]

Influenza A virus (FLUAV) infections are endemic in pork producing countries worldwide but in Brazil it was not considered an important pathogen in pigs. Since the emergence of 2009 pandemic H1N1 (H1N1pdm) FLUAV, many outbreaks of respiratory disease were observed in pig herds. The aim of this study was to evaluate FLUAV infection in swine in 48 pig farms located in seven Brazilian states with previous reports of influenza-like signs by clinical, serological and virological cross-sectional studies. Serological results showed that pigs from all farms had anti-influenza antibodies by NP-ELISA. Antibodies to H3N2, H1N2 and H1N1pdm were detected by HI in pigs from 24 farms. Co-infection with two or more FLUAV subtypes was detected in pigs in seven of those 24 farms. Detection of FLUAV in nasal swabs and oral fluids by RT-qPCR indicated a global concordance >81% for the two biological samples. Moreover, our results show that H1N1pdm, H1N2 and H3N2 viruses are widespread in Brazilian pig herds. The monitoring of FLUAV emergence and evolution in pigs is urgent, as well the study of the pathogenesis of Brazilian isolates, aiming to control influenza in pigs. [ABSTRACT FROM AUTHOR]

The evolutionary origins of the influenza A(H1N1)pdm09 virus that caused the first outbreak of the 2009 pandemic in Mexico remain unclear, highlighting the lack of swine surveillance in Latin American countries. Although Brazil has one of the largest swine populations in the world, influenza was not thought to be endemic in Brazil's swine until the major outbreaks of influenza A(H1N1)pdm09 in 2009. Through phylogenetic analysis of whole-genome sequences of influenza viruses of the H1N1, H1N2, and H3N2 subtypes collected in swine in Brazil during 2009-2012, we identified multiple previously uncharacterized influenza viruses of human seasonal H1N2 and H3N2 virus origin that have circulated undetected in swine for more than a decade. Viral diversity has further increased in Brazil through reassortment between co-circulating viruses, including A(H1N1)pdm09. The circulation of multiple divergent hemagglutinin lineages challenges the design of effective cross-protective vaccines and highlights the need for additional surveillance. [ABSTRACT FROM AUTHOR]