Seroprevalence of IgG1 and IgG4 Class Antibodies Against Mycobacterium avium subsp. paratuberculosis in Japanese Population

Abstract

Mycobacterium avium subsp. paratuberculosis (MAP) is the established causative agent of Johne's disease in cattle and other ruminants, and it has also been speculated to be a putative etiological agent of several human autoimmune diseases. It is acknowledged that dairy products deriving from infected animals play a role (could be vehicles) in exposing humans to MAP. MAP could stimulate the human immune system by means of their complex antigen (in the case of lipids, multivalent antigens) and may modulate it, acting as adjuvant molecules such as Freund's complete adjuvant. The immune system might be abnormally stimulated by the constant presence of MAP antigens (for example, in the dairy products), and this might be particularly relevant in genetically predisposed individuals. However, there is limited understanding about the current human exposure to MAP. The present study analyzed the antibody recognition profile of MAP lipophilic antigens in a cohort of 126 healthy Japanese. We measured the serum levels of total immunoglobulin G (IgG) and subclasses targeting MAP surface antigens through ethanol vortex indirect enzyme-linked immunosorbent assay (EVELISA) by using serum absorbed with Mycobacterium phlei. Elevated IgG (especially IgG1 and IgG4) responses were observed in 14% of the sera. To assess the specificity of EVELISA, the same samples were analyzed by means of a commercially available Johnelisa II kit. It was noteworthy that a high degree of correlation was observed when comparing the two methodologies (rs=0.7, p<0.0001). Moreover, in order to investigate the specificity of the binding, inhibition assay experiments were carried out also searching for antibodies against Bacillus Calmette-Guérin antigens, but no cross-reaction was observed. The result obtained represents the first evidence implying that the Japanese population is exposed to MAP, and additionally the existence of a foodborne chain of exposure that transmits MAP antigens to humans.

Mycobacterium avium Subsp. paratuberculosis Induces Specific IgE Production in Japanese People with Allergies

“…Considering that the incidence of bovine paratuberculosis and the level of contamination with MAP antigen in dairy products are growing year by year [31], there is also the possibility that oral exposure to MAP antigens can increase. Since the incidence of bovine paratuberculosis is very low in Japan, the Japanese population could be exposed to MAP via contaminated dairy products imported from Western countries, where the prevalence of paratuberculosis is very high [20]. …”

“…Preparation of MAP (strain ATCC 19698) and Bacillus Calmette-Guérin (BCG) (strain Tokyo 172) lipophilic antigen was performed as previously published [20]. MAP lipophilic antigen is an ethanol (crude) extract of MAP and its antigenicity is due to the lipid (chloroform extractable) and not to the protein (aqueous) fraction [25].…”

“…The shedding of MAP into milk is well known in the infected cattle, and there is much evidence of MAP contamination in milk, cheese, powdered milk for infants, and beef meat [19, 20]. The bacilli can also survive the pasteurization process [21].…”

“…The bacilli can also survive the pasteurization process [21]. Thus the existence of a food-born route of MAP exposure from animals to human is likely [20]. A recent seroprevalence study demonstrated the presence of an immunoglobulin G (IgG) subclass pattern against MAP lipophilic antigens [20] in healthy Japanese people.…”

“…Thus the existence of a food-born route of MAP exposure from animals to human is likely [20]. A recent seroprevalence study demonstrated the presence of an immunoglobulin G (IgG) subclass pattern against MAP lipophilic antigens [20] in healthy Japanese people. Of particular interest, the detection of IgG4 provides evidence of prolonged antigenic stimulation [22].…”