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Evolutionary Biology of Parasitism
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2023
Eric S. Loker, Bruce V. Hofkin
The study of MHC-parasite interactions is an active one, with intriguing new insights emerging. One is the extent to which MHC gene copies per genome vary both within and between species. We humans have relatively few MHC loci as do mice and chickens, but other groups like passerine birds and certain fish like cod have many more. One long-term study of the sedge warbler Acrocephalus schoenobaenus, a common migratory species known to have highly duplicated MHC genes, and of avian malaria parasites (Haemoproteus) which have consequential fitness effects on the birds, revealed a number of interesting trends. One was that the prevalence of avian malaria was a significant predictor of frequency changes in particular MHC supertypes over the years, and the second was that birds with large overall MHC supertype diversity had greater resistance to malaria. Far from finding an optimum number of MHC alleles, more seems better in sedge warblers. Similar results have been found with other bird species in their response to avian malaria.
The malaria parasites
Published in David A Warrell, Herbert M Gilles, Essential Malariology, 2017
Robert E Sinden, Herbert M Gilles
Malaria parasites of birds are found in nearly every country in the world. This is largely due to the migratory flights of birds and the widespread occurrence of susceptible mosquito vectors. It was Danilewsky in Russia who, in 1884, first observed malaria parasites in the blood of birds. His major work, published in 1894, indicated the wide distribution of these parasites. Ross in 1897 demonstrated the development of P. relictum in culicine mosquitoes fed on infected sparrows. In 1899–1900, Grassi and other Italian workers described a number of avian malaria parasites and their transmission by mosquitoes.
Parasites and Conservation Biology
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2015
Eric S. Loker, Bruce V. Hofkin
One of the most famous examples of how parasites can cause extinctions of host species, and thereby pose considerable concerns for conservation biologists, is provided by the indigenous birds of Hawaii and their exposure to avian malaria.What is particularly noteworthy about the honeycreepers found in Hawaii?Why are they so susceptible to avian malaria?What additional factors have favored the continued persistence of avian malaria in Hawaii?What factors have enabled some indigenous bird species to survive?How does climate change figure into this example?Is there any hope for the native birds? If so, why?
Transmission-Blocking Vaccines: Harnessing Herd Immunity for Malaria Elimination
Published in Expert Review of Vaccines, 2021
TBV development has primarily focused on antigens expressed on the surface of gametes, zygotes, and ookinetes (Figure 1C). The first candidates (Pfs230, Pfs48/45, Pfs25, and Pfs28) – which remain the leading candidates more than 3 decades later – were identified using functional monoclonal antibodies generated by vaccinating animals with gametes [11,12] or ookinetes [13]. Initially identified by their orthologues in the avian malaria parasite P. gallinaceum, the P. falciparum antigens Pfs230 and Pfs48/45 are expressed by gametocytes, appear on the surface of gametes and zygotes, then are shed as zygotes transition to ookinetes [13]. Owing to their stages of expression, antibodies against Pfs230 and Pfs48/45 exert their effects before gamete fertilization, and Pfs230 and Pfs48/45 induce antibodies during human infection [14]. As a consequence, vaccine responses to Pfs230 or Pfs48/45 may be boosted during infections and this could prolong durability of vaccine activity. Clinical trials of Pfs230 or Pfs48/45 vaccines should model antibody decay to understand the impact of intercurrent malaria infections.
Considerations for the governance of gene drive organisms
Published in Pathogens and Global Health, 2018
Larisa Rudenko, Megan J. Palmer, Kenneth Oye
The call for community engagement extends to publications intended for a non-scientific audience as well. A commentary describing gene drives as a tool for using either suppression or alteration drives to combat avian malaria has been published in The New Yorker [93], and calls on an ‘informed society’ to make the decision to proceed with the technology or not. Such calls, and the experience of the IUCN indicate that there should not be an expectation that engagement will lead to acceptance, but may result in different outcomes depending on the participants and the issue(s). Neither the New Yorker article nor do the other calls for public engagement provide recommendations for how those engagements should be held, who the informed society is, and what subgoups of that society should be afforded what degree of control.