Evidence of in-utero Mycobacterium avium subsp. paratuberculosis infection in two pregnant goats: PCR detection, bacterial isolation, and molecular genotyping.

Importance: In-utero transmission of Johne's disease (JD), a chronic enteric condition caused by Mycobacterium avium subspecies paratuberculosis (MAP), has been reported. However, no study to date has confirmed in-utero transmission of MAP to fetuses in clinically infected Korean black goats.

Objective: To provide evidence of in-utero transmission in two clinically JD-infected pregnant goats and their fetuses through polymerase chain reaction (PCR) detection, bacterial isolation, and molecular epidemiological characterization.

Methods: Two pregnant goats were diagnosed with JD through clinical assessment, enzyme-linked immunosorbent assay, PCR detection, and bacterial culture. MAP isolates were genotyped using IS1311 PCR-restriction enzyme analysis and the mycobacterial interspersed repetitive unit-variable number tandem repeat (MIRU-VNTR) method.

Results: ISMav02 gene was detected in the jejunum, mesenteric lymph nodes (MLN), and placentomes of both goats. In addition, positive bands were observed in the cecum and colon tissues from Goat #2. All fetal intestine samples from both goats were positive, while the umbilical cords were positive in one fetus from each goat. Two MAP isolates were obtained: one from the placentome (Goat #1) and the other from the MLNs (Goat #2). Genotyping revealed two distinct cattle-type strains, including INRA Nouzilly MIRU-VNTR (INMV) 248 (novel type) and INMV 13.

Conclusions and relevance: This study provides the first direct evidence of in-utero MAP infection in clinically JD-infected pregnant goats in the Republic of Korea. Two distinct MIRU-VNTR genotypes were identified, including a novel MAP strain, highlighting the need for improved management strategies to prevent vertical transmission of JD and address genetic diversity within goat herds.