Evaluation of LN34 Pan-Lyssavirus RT-qPCR assay for rabies diagnosis in Brazil.

Rabies, a fatal zoonotic viral disease affecting mammals, including humans, remains a significant global health concern, particularly in low-income countries. The disease, primarily transmitted through infected animal saliva, prompts urgent diagnosis for timely post-exposure prophylaxis (PEP). The gold standard diagnostic test, direct fluorescent antibody test (dFAT), while sensitive, suffers from limitations such as subjective interpretation and high costs. As a confirmatory technique, the LN34 Pan-Lyssavirus RT-qPCR assay has emerged as a promising tool for universal Lyssavirus detection. This study evaluated its performance using 130 rabies virus isolates representing eleven Brazilian variants and 303 clinical samples from surveillance operations. The LN34 assay demonstrated 100% sensitivity and 98% specificity compared to dFAT. Additionally, it detected all samples, including those missed by dFAT, indicating superior sensitivity. The assay's specificity was confirmed through Sanger nucleotide sequencing, with only a minimal false-positive rate. Comparative analysis revealed higher accuracy and concordance with dFAT than traditional rabies tissue culture infection tests (RTCIT). False-negative RTCIT results were attributed to low viral load or suboptimal sampling. These findings underscore the LN34 assay's utility as a confirmatory technique, enhancing rabies surveillance and control in Brazil. Its widespread adoption could significantly improve diagnostic sensitivity, crucial for effective PEP and public health interventions.

Comparison of five different laboratory techniques for the rabies diagnosis in clinically suspected cattle in Brazil.

The direct-fluorescent antibody test (dFAT) is considered the "gold standard" assay to diagnose rabies. However, it is crucial to develop molecular techniques, such as RT-PCR and RT-qPCR, since many laboratories lack the needed supplies for performing complementary methods (viral isolation, for example). For this purpose, diagnostic techniques must be specific and sensitive to guarantee accuracy. This present investigation aimed to detect rabies virus (RABV) in 126 clinically suspected cattle in Brazil using different diagnostic tests [dFAT, mouse inoculation test (MIT), immunohistochemistry (IHC), RT-PCR and RT-qPCR] and to compare those results obtained under routine laboratory conditions. The results of the present investigation demonstrate that the molecular techniques are more sensitive and may detect low viral load, even though the non-homogeneous viral distribution caused a false-negative result in dFAT. We also observed a usual alteration in antigens distribution among regions of the central nervous system (CNS). By both dFAT and IHC assays, the most reliable CNS structures were thalamus and midbrain. Although this investigation demonstrated diagnostic sensitivity and specificity close to 100 % in all laboratory techniques employed, a dFAT auxiliary test is required for bovine specimens, such as molecular techniques, when there are poor sampling conditions (low viral load combined with unavailability of brainstem structures).

Bovine rotavirus in turkeys with enteritis.

Rotaviruses are the main agents responsible for diarrhea in different animal species and for infantile gastroenteritis. These viruses have been isolated from various avian species and have often been associated with poult enteritis and mortality syndrome. Nevertheless, the knowledge of rotavirus infection in turkeys is scarce. Six group A rotavirus strains obtained from pooled enteric contents of diarrheic turkeys were isolated in MA-104 cell culture and typed as G(6)P(1), a typical bovine rotavirus genotype. Additionally, the electropherotypes showed a migration pattern identical to the Nebraska calf diarrhea virus, and the complete NSP4 gene phylogeny showed that all six strains segregated in the genotype E2. Taken together, these results point toward a cattle-to-turkey rotavirus transmission. As a conclusion, bovine-origin rotavirus can be found in turkeys, and this transmission route must now be considered for the improvement of the health status in turkey farms.

First isolation of equine herpesvirus type 1 from a horse with neurological disease in brazil

ABSTRACT This report describes the first Brazilian equine herpesvirus type 1 (EHV-1) isolation from a single fatal equine herpes myeloencephalopathy case in a mare. The isolation of EHV-1 was confirmed from the first passage of cerebrospinal fluid (CSF) sample in Vero cells by PCR and virus neutralization assay. As virus isolation from CSF is unlikely to be successful, as has been shown in several case reports, this circumstantial evidence suggests that the neurological disease was caused by particularly neurovirulent strain of EHV-1.

RESUMO O presente relato refere-se ao primeiro isolamento no Brasil do herpesvírus eqüino tipo 1 (HVE-1) proveniente de um caso clínico de mieloncefalopatia herpética em uma égua, que evoluiu para o óbito. O isolado do HVE-1, denominado 07/05, foi obtido a partir de uma amostra de líquor na primeira passagem em células Vero, confirmando-se sua identidade pela PCR e pela prova de neutralização viral. Como o isolamento viral a partir do líquor geralmente não é bem sucedido, conforme demonstrado em vários relatos de casos, o presente achado sugere que a doença neurológica foi causada por uma amostra particularmente neurovirulenta de HVE-1.