ウイルス感染が寄生虫感染の症状を軽減 ―子牛下痢症における新たな制御戦略につながる発見―

2026-02-24 東北大学

東北大学大学院農学研究科東京農工大学の研究グループは、子牛下痢症の主要因であるロタウイルスとクリプトスポリジウムの共感染を解析し、ロタウイルスの不顕性感染が後続する寄生虫感染による下痢期間を有意に短縮することを明らかにした。さらに細胞実験により、ロタウイルス由来タンパク質NSP4が寄生虫感染を抑制することを確認。本成果は、共感染が必ずしも症状悪化を招かないことを示し、新たな制御戦略構築への可能性を示す。成果はFrontiers in Veterinary Scienceに掲載された。

ウイルス感染が寄生虫感染の症状を軽減 ―子牛下痢症における新たな制御戦略につながる発見―

図1. 本研究の概略図

<関連情報>

クリプトスポリジウムとロタウイルスの同時感染が子牛の感染性に及ぼす影響 Influence of Cryptosporidium and rotavirus co-infection on infectivity in calves

Fumi Murakoshi,Megumi Itoh,Rofaida Mostafa Soliman,Tatsunori Masatani,Kenichi Shibano,Takaaki Nakaya,Kentaro Kato

Frontiers in Veterinary Science  Published:17 February 2026

DOI:https://doi.org/10.3389/fvets.2026.1715161

Abstract

Rotavirus A (RVA; species Rotavirus alphagastroenteritidis) and Cryptosporidium spp. are major enteric pathogens in infants and neonatal calves, causing severe diarrhea that can lead to fatal outcomes. These pathogens thus pose challenges in both public health and the livestock industries. Although co-infections are common, their pathogenesis remains poorly understood. Here, we conducted a longitudinal investigation in naturally infected calves to assess the impact of co-infection with rotavirus and Cryptosporidium. Infection status was determined based on daily fecal antigen testing and oocyst per gram (OPG) counts from birth to 22 days of age. Based on these criteria, seven calves were classified as having Cryptosporidium mono-infection and three calves as having mixed infection. We found that subclinical infection with bovine rotavirus significantly shortened the duration of diarrhea caused by Cryptosporidium parvum in calves and reduced initial oocyst shedding. Furthermore, in vitro experiments using the bovine intestinal epitheliocyte (BIE) cell line demonstrated that the BRV Lincoln strain (G6, P[1]) non-structural protein 4 (NSP4) inhibits C. parvum infection, possibly by interfering with the host sodium-glucose co-transporter 1 (SGLT1). Our study highlights a potential novel strategy for controlling both BRV and C. parvum by exploiting their interactions during co-infection.

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