Serological surveillance and factors associated with influenza A virus in backyard pigs in Southern Brazil.

Backyard pig populations are not monitored for influenza A virus (IAV) in Brazil and there are limited data about seroprevalence and risk factors in these populations. Our goal was to assess possible factors associated with IAV seroprevalence in backyard pig populations using an indirect ELISA protocol based on a recombinant nucleoprotein. Following the IAV screening using NP-ELISA, subtype-specific serology based on hemagglutination inhibition (HI) assay of the ELISA-positive pigs was conducted. The survey comprised a total of 1,667 sera samples collected in 2012 and 2014 in 479 holdings and the estimated seroprevalence was 5.3% (3.84%-7.33%) and 2.3% (1.34%-3.71%) in the respective years. In both years, H1N1pdm09 was the most prevalent subtype. The multivariable analysis showed main factors such as "age," "sex," "number of suckling pigs" and "neighbours raising pigs" that presented the greatest effect on IAV seroprevalence in these pig populations. These factors may be associated with the low biosecurity measures and management of backyard holdings. In addition, the low IAV seroprevalences found in these backyard pig populations could be related to a low number of animals in each pig holding and low animal movement/replacement that do not favour IAV transmission dynamics. This low frequency of H1N1pdm09 seropositive pigs could also be due to sporadic human-to-pig transmission of what is now a human seasonal influenza A virus; however, these factors should be explored in future studies. Herein, these results highlight the importance of IAV continued surveillance in backyard pig holdings, since it is poorly known which IAVs are circulating in these populations and the risk they could pose to public health and virus transmission to commercial farms.

Identification and partial characterization of a gut Rhipicephalus appendiculatus cystatin.

Vaccines are among the alternative tick control methods expected to replace at least in part the volumes of chemical acaricides currently used worldwide. However, a vaccination approach depends on a host immune response against proteins that are essential to tick physiology. The cystatin family is a protein class recently investigated to compose an effective antigen in a tick vaccine. In this study, a cDNA from Rhipicephalus appendiculatus with high sequence similarity to cystatins type 2 was identified by random sequencing analysis and called R. appendiculatus cystatin 1 (Ra-cyst-1). DNA sequence analysis showed that the cloned Ra-cyst-1 has a 423-bp open reading frame and codified to a 140-amino acid polypeptide. The putative mature protein consists of 115 amino acid residues with a deduced molecular weight of 12.8kDa. The highly conserved G (P-I), QxVxG (P-II), and PW (P-III) type 2 cystatins motifs are present in Ra-cyst-1 cDNA. RT-PCR analysis showed that the Ra-cyst-1 gene is expressed in nymph, male, and female midgut following blood feeding, but not in the salivary glands of fed females. In addition, Western blot revealed that recombinant Ra-cyst-1 was not recognized by sera derived from rabbits infested with ticks, suggesting that this cystatin is not secreted into the host during infestation. We hypothesize that Ra-cyst-1 may play a role in the tick feeding process and could be a concealed antigen candidate in further anti-tick vaccination trials.

[Expression and enzymatic activity of glutathione s-transferase in tissues of Boophilus microplus females]. / Expressão e atividade enzimática de glutationa s-transferase em tecidos de fêmeas de Boophilus microplus.

Cellular detoxification and excretion enzymes are important to the maintenance of cellular homeostasis. In this work mRNA transcription, protein expression and enzymatic activity of Glutathione S-transferases (GSTs), enzymes involved in the excretion of endo and xenobiotic compounds were analyzed. These parameters are elements believed to protect cells against chemical toxicity and oxidative stress in different tissues (salivary gland, ovary and synganglion) from partially engorged females and engorged females of Boophilus microplus. The results presented showed elevated GST activity in partially engorged females. The enzymatic activity decreased during the preoviposition period in engorged females. GST mRNA transcription was detected in salivary glands and synganglion from partially engorged and engorged females, but not in ovary. The results of this work help to elucidate the role of GST in tick development and assist in the understanding of the importance of GST in tick females during the preparation for oviposition.