Table 4. Summary of postulates and findings about interactions of PMMoV with the host immune system, its replication in non-plant tissues, and its potential link with clinical signs.

Postulate	Plant virus	Finding	Reference
PMMoV may interact with the host immune system	Pepper mild mottle virus	Specific immune response as indicated by positive anti-PMMoV IgM antibody testing in patients with PMMoV in stool	Present study
	Cowpea severe mosaic virus, Alfalfa mosaic virus	Evidence of systemic immune response (specific synthesis of IgG and IgA in sera) in mice immunized orally with Cowpea severe mosaic virus (CPSMV) in the absence of immunoadjuvants. Similar results were observed with viral particles of Alfalfa mosaic virus and chimeric plant virus particles	[23]–[25]
	Tomato spotted wilt virus	Induction of a strong immune response in Frankliniella occidentalis, its main insect vector	[26]
	Pepper mild mottle virus	High PMMoV loads in stool of patients and food products containing pepper	[7], Present study
PMMoV may replicate in humans	Pepper mild mottle virus	High PMMoV loads in stool of patients and food products containing pepper	[7], Present study
	Pepper mild mottle virus, Tobamovirus	High viral stability	[8], [34], [35]
	Pepper mild mottle virus	PMMoV detected from human stool is viable	[7]
	Tomato spotted wilt virus; Maize rayado fino virus	Some plant viruses are able to multiply in non-plant tissue (in insect tissues)	[26]–[28]
	Nanovirus	Evidence that a plant virus switched hosts to infect a vertebrate	[16]
	Tomato spotted wilt virus	Expression of a viral polymerase-bound factor turned human cell lines, HeLa and diploid fibroblasts, permissive to Tomato spotted wilt virus	[30]
	Tobacco mosaic virus	Plant virus particles could be assembled in Escherichia coli	[36]
PMMoV may induce clinical signs	Tomato yellow leaf curl virus	Reduction of lifespan and fecundity of the insect vector (Bemisia tabaci) during viral infection	[29]
	Tobacco mosaic virus	Recovery of culturable tobacco mosaic virus from sputum and thoracentesis fluids obtained from cigarette smokers with a history of pulmonary disease	[31]–[33]
	Pepper mild mottle virus	Fever and abdominal pains are significantly more frequent in patients with PMMoV-positive stool	Present study