Natural Infection of Dairy Cows with Bovine Leukemia Virus Affects Immunoglobulin Levels in Saliva and Serum but Not Milk

Abstract

Bovine leukemia virus (BLV) is a retroviral infection that disrupts the immune function of infected animals. It is widespread among U.S. dairy cattle. In this pilot study, the average total IgA and IgM concentrations in milk, saliva, and serum samples from BLV ELISA-positive (ELISA+) dairy cows were compared against samples from BLV ELISA-negative (ELISA−) cows using the Kruskal–Wallis test (with ties). The results from ELISA+ cows were also stratified by lymphocyte count (LC) and proviral load (PVL). In milk and saliva from ELISA+ cows, the average total IgA and IgM concentrations were decreased compared to ELISA− cows, although this was only statistically significant for saliva IgM in cows with low PVL (p = 0.0424). Numerically, the average total IgA concentrations were 33.6% lower in milk and 23.7% lower in saliva, and the average total IgM concentrations were 42.4% lower in milk and 15.5% lower in saliva. No significant differences were observed in the total serum IgA concentrations, regardless of PVL and LC. The total serum IgM from ELISA+ cows was significantly decreased (p = 0.0223), with the largest decreases occurring in the highest PVL and LC subgroups. This pilot study is a first step in investigating the impact of BLV on mucosal immunity and will require further exploration in each of the various stages of disease progression.

Changes in immunoglobulin A and immunoglobulin G concentrations in the saliva of Japanese Black beef cows during calving: A pilot study

“…For saliva sampling, a collection polymer swab (Saliva Bio Children's Swab; Salimetrics, Carlsbad, CA, USA) was inserted through the mouth and allowed to be chewed several times to absorb saliva into the swab (Dziuba et al, 2021). Then, the swab was stored in ice‐cooled coolers for transport to the laboratory, where they were centrifuged at 1500× g for 15 min and frozen at −30°C until IgA, IgG, and albumin analyses were conducted (Dziuba et al, 2021).…”

“…Optical density values were measured at 450 nm using a microplate reader (Wallac 1420 ARVO MX; Perkin Elmer, Waltham, MA, USA) and compared with the standard curve run on each plate to determine concentrations. Samples were tested in duplicate on the same plate, and the results were averaged (Dziuba et al, 2021).…”

“…Individual saliva samples from primiparous and multiparous cows were collected thrice: À2 (À16.7 AE 4.5 and À17.8 AE 2.0 days postpartum, respectively), 0 (3.9 AE 1.8 and 4.3 AE 1.7 h after calving, respectively), and 2 (13.5 AE 0.7 and 13.8 AE 0.4 days postpartum, respectively) weeks postpartum. For saliva sampling, a collection polymer swab (Saliva Bio Children's Swab; Salimetrics, Carlsbad, CA, USA) was inserted through the mouth and allowed to be chewed several times to absorb saliva into the swab (Dziuba et al, 2021). Then, the swab was stored in ice-cooled coolers for transport to the laboratory, where they were centrifuged at 1500Âg for 15 min and frozen at À30 C until IgA, IgG, and albumin analyses were conducted (Dziuba et al, 2021).…”

“…Samples were tested in duplicate on the same plate, and the results were averaged (Dziuba et al, 2021).…”