The Bleomycin datasheet in vitro effects of lactoferrin against viruses causing common infections are summarized in Table 1. Many viruses cause the common cold. Among common cold viruses, the antiviral activity of lactoferrin is reported against the respiratory syncytial (RS) virus [9], [10] and [11] and parainfluenza virus [12]. The anti-influenza virus activity of lactoferrin is also reported against the influenza A virus

H1N1, H3N2, and H5N1 (avian) [13], [14], [15] and [16]. Effects of orally administered lactoferrin on common viral infections are summarized in Table 2. A questionnaire survey of adult women revealed that consumption of lactoferrin-containing tablets decreases the incidence of common cold-like symptoms and gastroenteritis symptoms [17]. Another study reported that lactoferrin administration with milk immunoglobulin reduces the incidence of the common cold in humans [18]. On the other hand, lactoferrin did not show a favorable effect in an RS virus infection model of mice [19]. In a mouse influenza

virus-infection model, lactoferrin feeding lowered lung inflammatory markers [20]. There is no report regarding the effects of lactoferrin on influenza in humans yet. NK cells recognize and destroy target cells infected by influenza or the parainfluenza virus [21] and the relationship between the frequency of the common cold and the activity of NK cells has been reported [22]. It has been shown that lactoferrin feeding enhances NK cell activity in patients with find more adenomatous colorectal polyps [23] and the NK cell number in mice [24]. Therefore, increased NK cell activity or number by lactoferrin may mediate at least partly the host protection against the common cold and influenza.

Gastroenteritis caused by rotavirus and norovirus is a major illness prevalent in winter. Rotavirus causes gastroenteritis only in children. Norovirus is an extremely important emerging human pathogen that causes a majority of gastroenteritis outbreaks worldwide. The in vitro anti-rotavirus effects of lactoferrin have been reported [25] and [26] (Table 1). The human norovirus remains difficult to study, because there is a lack of cell cultures and animal models. Instead, feline calicivirus and murine norovirus, Methane monooxygenase which can be cultured and share a number of biochemical properties, similar genomic organization and primary RNA sequences with human norovirus, have been used as a virus surrogate to study human norovirus. A study using feline calicivirus showed that bovine lactoferrin inhibits the viral infection of Crandell-Reese feline kidney cells by binding to the cells and lactoferricin B inhibits the infection by binding to the virus [27]. Bovine lactoferrin also decreased murine norovirus infection to murine macrophage cell line Raw264.7 through inhibition of the initial murine norovirus attachment to cells and the subsequent interference with murine norovirus replication [28].