Evaluation of the effect of sample suspension concentration and viral load on the outcome of the rabies tissue culture infection test

• Published in: Archives of virology 2024-01, Vol.169 (1), p.3-3, Article 3
• Main Authors: de Souza, Tatiane de Cassia Pardo, de Sousa e Silva, Gilmara, de Oliveira Fahl, Willian, Rodrigues, Adriana Candido, Asano, Karen Miyuki, Scheffer, Karin Corrêa, Mori, Enio, Siena, Amanda, Iamamoto, Keila
• Format: Article
• Language: English
• Subjects: Animals; Bats; Biomedical and Life Sciences; Biomedicine; Brain; Brief Report; Cattle; Cell culture; Infections; Infectious Diseases; Medical Microbiology; Nervous system; Rabies; Rabies - diagnosis; Rabies virus; Reproducibility; Reproducibility of Results; Tissue culture; Viral Load; Virology
• ISSN: 0304-8608; 1432-8798
• DOI: 10.1007/s00705-023-05922-3

In this study, we examined various brain suspension concentrations and viral loads in Neuro-2a cell cultures using 20 rabies-positive bovine samples. The reproducibility of results varied: 65% showed consistent outcomes across all concentrations, while 35% disagreed in at least one. Viral titers ranged from less than 25 × 10 1 to 25 × 10 3.50 TCID 50 /mL, with 20% below 25 × 10 1 TCID 50 /mL. Concentrations between 5% and 20% yielded over 90% agreement in positive results, but at 30%, agreement dropped from 85% to 50%. Cell confluence was successfully maintained at 5%, 10%, and 20%, while concentrations of 30% and above led to confluence loss. Low viral loads also negatively impacted reproducibility. These results suggest that sample concentration has a direct influence on preservation of cell confluence and that low viral loads may influence the reproducibility of the rabies tissue culture infection test (RTCIT).