Detection of high antibodies titers against rat leukemia virus in an outbreak of reproductive disorders and lymphomas in Wistar rats.

Young female Wistar rats from a specific pathogen free breeding colony presented an outbreak of infertility along with neurological symptoms and malignant lymphomas. We evaluated the presence and the potential role of the rat leukemia virus (RaLV) in the disease because these clinical signs could be compatible with a retrovirus. RaLV is a mammalian type C endogenous retrovirus initially isolated from in vitro Sprague-Dawley rat embryo cultures.

Molecular survey of pyrethroid and fipronil resistance in isolates of Rhipicephalus microplus in the north of Uruguay.

The resistance of Rhipicephalus microplus to acaricides is a serious control problem, so its early diagnosis by a molecular technique is important. This study aims to develop a multiplex allele-specific polymerase chain reaction (PCR) for single-nucleotide polymorphisms (SNPs) in the para-sodium channel gene and in the GABA-Cl gene, associated with pyrethroids (cypermethrin and flumethrin) and fipronil resistance, respectively. We used 22 tick field isolates from farms with tick control problems (sampling convenience).

Multiplex allele-specific polymerase chain reaction to detect kdr and rdl mutations in the cattle tick Rhipicephalus microplus (Acari: Ixodidae).

The resistance of Rhipicephalus microplus to pyrethroids is widely dispersed worldwide and has been associated with several nucleotide substitutions in its target site, the para-sodium ion channel (Na-channel) gene. The resistance of the tick to fipronil has been increasing in South America, and mutations in the GABA-gated chloride channel (GABA-Cl) have been described in fipronil-resistant tick strains. We developed a multiplex allele-specific PCR (mAS-PCR) to screen for single-nucleotide polymorphisms (SNPs) associated with the resistance to pyrethroids (knockdown resistance or kdr) and fipronil (resistance to dieldrin or rdl) in susceptible tick populations from Uruguay (n = 11) and the Rio Grande do Sul state in Southern Brazil (n = 15).