Cochliobolus lunatus

{{Speciesbox | image = Curvularia lunata conidia.jpg | taxon = Cochliobolus lunatus | authority = R.R. Nelson & Haasis, (1964) | synonyms = ''Acrothecium lunatum'' Wakker, in Wakk. & Went., (1898) ''Curvularia lunata'' (Wakker) Boedijn, (1933) ''Curvularia lunata var. lunata'' (Wakker) Boedijn, (1933) ''Pseudocochliobolus lunatus'' (R.R. Nelson & Haasis) Tsuda, Ueyama & Nishih., (1978) }}

'''''Cochliobolus lunatus''''' is a fungal plant pathogen that can cause disease in humans and other animals. The anamorph of this fungus is known as ''Curvularia lunata'', while ''C. lunatus'' denotes the teleomorph or sexual stage. They are, however, the same biological entity. ''C. lunatus'' is the most commonly reported species in clinical cases of reported ''Cochliobolus'' infection.<ref>{{cite journal|last=da Cunha|first=KC|author2=Sutton DA |author3=Fothergil AW |author4=Gene J |author5=Cano J |author6=Madrid H |author7=de Hoog S |author8=Crous PW |author9=Guarro J |title=In vitro antifungal susceptibility and molecular identity of 99 clinical isolates of the opportunistic fungal species Curvularia|journal= Diag Micr Infec Dis |year=2013|volume=76|issue=2 |pages=168–74|doi=10.1016/j.diagmicrobio.2013.02.034 |pmid=23558007 }}</ref>

== Morphology == Macroscopic features of ''C. lunatus'' include brown to black colour, hairy, velvety or woolly texture, and loosely arranged and rapidly growing colonies on potato dextrose agar medium. Microscopically, the conidiophores are septate. There is great variety in the arrangement of the conidiophores, as they can be isolated or in groups, straight or bent, show simple or geniculate growth pattern, and vary in colour ranging from pale to dark brown. Conidiophore length can reach 650 μm and are often 5–9 μm wide, with swollen bases ranging from 10–15 μm in diameter. Conidia develop at the tips and sides of the spores and have a smooth texture. ''C. lunatus'' is differentiated from other ''Cochliobolus'' species by its three septa and four cells, with the first and last cell usually of a paler shade of brown than those in the middle. Conidia range from 9–15 μm in diameter and have a curved appearance.<ref>{{cite journal|last=Nelson|author2=Haasis|title=Cochliobolus lunatus|journal=Mycologia|year=1964|volume=56|pages=316|doi=10.2307/3756550 |jstor=3756550 }}</ref><ref>{{cite web|title=''Curvularia'' spp.|url=http://doctorfungus.org/thefungi/Curvularia.php|archive-url=https://web.archive.org/web/20101121040351/http://doctorfungus.org/thefungi/Curvularia.php|url-status=dead|archive-date=21 November 2010|accessdate=17 October 2013}}</ref>

== Phylogeny == The order Pleosporales includes many plant pathogens of economic importance. ''C. lunatus'' belongs to Clade-II in the family Pleosporaceae, which is the largest family in its order.<ref>{{cite journal |vauthors=Zhang Y, Schoch CL, Fournier J, Crous PW, de Gruyter J, Woudenberg JH, Hirayama K, Tanaka K, Pointing SB, Spatafora JW, Hyde KD |title=Multi-locus phylogeny of pleosporales: a taxonomic, ecological and evolutionary re-revaluation|journal= Stud Mycol |year=2009|volume=64|issue=1|pages=85–102–S5|doi=10.3114/sim.2009.64.04|pmc=2816967|pmid=20169024}}</ref> The ''{{ Visible anchor |Clk1}}'' MAPK gene in ''C. lunatus'' is homologous to MAPK genes such as ''{{ Visible anchor |Pmk1}}'', ''{{ Visible anchor |Cmk1}}'', ''Chk1'' and ''{{ Visible anchor |Ptk1}}'' of other fungal pathogens, which are highly conserved in eukaryotic lineages.<ref name = "Clk1" /> There are over 80 species in the genus.{{clarify|date=March 2023|reason=And we care why? Delete this unless there's a reason.}}<ref>{{cite journal|last=da Cunha|first=KC|author2=Sutton DA |author3=Fothergill AW |author4=Gene J |author5=Cano J |author6=Madrid H |author7=de Hoog S |author8=Crous PW |author9=Guarro J |title=In vitro antifungal susceptibility and molecular identity of 99 clinical isolates of the opportunistic fungal species Curvularia|journal= Diag Micr Infec Dis |year=2013|volume=76|issue=2 |pages=168–74|doi=10.1016/j.diagmicrobio.2013.02.034 |pmid=23558007 }}</ref>

== Ecology == ''Cochliobolus lunatus'' has a widespread distribution, though it is especially prevalent in the tropics and subtropics.<ref>{{cite web|title=''Curvularia'' spp.|url=http://doctorfungus.org/thefungi/Curvularia.php|archive-url=https://web.archive.org/web/20101121040351/http://doctorfungus.org/thefungi/Curvularia.php|url-status=dead|archive-date=21 November 2010|accessdate=17 October 2013}}</ref> Infection is caused by airborne conidia and ascospores, however, sclerotioid ''C. lunatus'' can also survive in the soil. The optimal temperature for ''in vitro'' growth and infection ranges from {{convert|24-30|C|F}} while death results from exposure at {{convert|59|C|F}} for a 1 minute duration, or {{convert|55|C|F}} for a 5 minute duration. Successful plant host infection requires the host surface to be wet for 13 hours.<ref>{{cite journal|last=Nelson|author2=Haasis|title=Cochliobolus lunatus|journal= Mycologia |year=1964|volume=56|pages=316|doi=10.2307/3756550 |jstor=3756550 }}</ref> The majority of clinical cases have been reported in India, the United States, Brazil, Japan and Australia.<ref>{{cite journal|last=da Cunha|first=KC|author2=Sutton DA |author3=Fothergil AW |author4=Gene J |author5=Cano J |author6=Madrid H |author7=de Hoog S |author8=Crous PW |author9=Guarro J |title=In vitro antifungal susceptibility and molecular identity of 99 clinical isolates of the opportunistic fungal species ''Curvularia lunata''|journal= Diag Micr Infec Dis |year=2013|volume=76|issue=2 |pages=168–74|doi=10.1016/j.diagmicrobio.2013.02.034 |pmid=23558007 }}</ref>

== Pathogenicity and therapy ==

=== Plant diseases === ''Cochliobolus lunatus'' is best known as the causative agent of seedling blight and seed germination failure in monocotyledon crops such as sugarcane, rice, millet<ref>{{cite journal|last=Nelson|author2=Haasis|title=Cochliobolus lunatus|journal= Mycologia |year=1964|volume=56|pages=316|doi=10.2307/3756550 |jstor=3756550 }}</ref> and maize (corn).<ref name = "Clk1" /> ''C. lunatus'' also causes leaf spot on a wide variety of angiosperm hosts, where each lesion contains a sporulating mass of fungi at its center. The ''Clk1'' gene plays an important role in fungal growth during the infection process, specifically conidiation, which is vital to the process of foliar infection.<ref name = "Clk1" >{{cite journal|last=Gao|first=SG|author2=Zhou FH|author3=Liu T|author4=Li YY|author5=Chen J|title=A MAP kinase gene, ''Clk1'', is required for conidiation and pathogenicity in the phytopathogenic fungus ''Curvularia lunata''|journal= J Basic Microbiol |year=2012|volume=53|issue=3|pages=214–223|doi=10.1002/jobm.201100518|pmid=22733544 |s2cid=5842038 }}</ref> Fungicides, in particular those with organo-mercurial compounds, have been associated with effective eradication of this pathogen.<ref>{{cite journal|last=Nelson|author2=Haasis|title=''Cochliobolus lunatus''|journal= Mycologia |year=1964|volume=56|pages=316|doi=10.2307/3756550 |jstor=3756550 }}</ref>

=== Human diseases ===

==== Phaeohyphomycoses ==== ''Cochliobolus lunatus'' is one of the main causative agents of phaeohyphomycosis. Initial infection via breaks to the epidermal barrier or the inhalation of spores can lead to disseminated infections, which are often associated with a poor prognosis.<ref>{{cite book|last=Kayser|first=FH|title=Medical Microbiology|year=2005|publisher= Georg Thieme Verlag |location=Stuttgart}}</ref><ref>{{cite web|title=Phaeohyphomycoses|url=http://www.doctorfungus.org/mycoses/human/other/phaeohyphomycosis.php|accessdate=24 October 2013|archive-url=https://archive.today/20131118022500/http://www.doctorfungus.org/mycoses/human/other/phaeohyphomycosis.php|archive-date=18 November 2013|url-status=dead}}</ref> ''C. lunatus'' is an opportunistic pathogen, infecting immunocompromised patients and those on rigorous steroid drug regimens such as solid organ transplant recipients, advanced AIDS patients and cancer patients.<ref>{{cite book|last=Berman|first=JJ|title=Taxonomic guide to infectious diseases: understanding the biological classes of pathogenic organisms 1st Ed.|year=2012|publisher=Elsevier/Academic Press|location=London}}</ref><ref>{{cite book|last=Perfect|first=JR|title=Antifungal Therapy|year=2009|publisher=Informa Healthcare|location=New York}}</ref> Dematiaceous fungi such as ''C. lunatus'' can facilitate foreign body infections of catheters, heart valves and pacemakers, for example.<ref>{{cite book|last=Perfect|first=JR|title=Antifungal Therapy|year=2009|publisher=Informa Healthcare|location=New York}}</ref>

With regards to treatment, surgical excision using a method similar to Mohs surgery is preferred if the mycosis is accessible, especially for abscesses in the brain. Administration of antifungals is commonly indicated as secondary management therapy, though the specific best regimen depends on the nature and location of the phaeohyphomycosis.<ref>{{cite book|last=Berman|first=JJ|title=Taxonomic guide to infectious diseases: understanding the biological classes of pathogenic organisms 1st Ed.|year=2012|publisher=Elsevier/Academic Press|location=London}}</ref><ref>{{cite book|last=Perfect|first=JR|title=Antifungal Therapy|year=2009|publisher=Informa Healthcare|location=New York}}</ref> When treating immunocompromised patients, it is critical that the underlying disease is controlled, and immune modulators such as granulocyte-macrophage colony-stimulating factor and gamma interferon can be indicated when surgery or antifungals are not feasible alternatives.<ref>{{cite book|last=Perfect|first=JR|title=Antifungal Therapy|year=2009|publisher=Informa Healthcare|location=New York}}</ref>

==== Allergy ==== Allergic fungal manifestations include asthma, rhinitis, sinusitis and bronchopulmonary mycoses<ref>{{cite book|last=Maertens JA, Marr KA|title=Diagnosis of fungal infections|year=2007|publisher=Informa Healthcare|location=New York}}</ref> caused by a variety of etiological fungal agents including ''C. lunatus''.<ref>{{cite journal|last=Schubert MS|title=Allergic fungal sinusitis: pathophysiology, diagnosis and management|journal=Med Mycol|year=2009|volume=47|issue=s1|pages=S324–S330|doi=10.1080/13693780802314809|pmid=19330659 |doi-access=free}}</ref> These agents provoke humoral immune responses, characterized by type I (immediate) and type III (immune complex mediated) hypersensitivity reactions.<ref>{{cite book|last=Maertens JA, Marr KA|title=Diagnosis of fungal infections|year=2007|publisher=Informa Healthcare|location=New York}}</ref><ref>{{cite journal|last=Schubert MS|title=Allergic fungal sinusitis: pathophysiology, diagnosis and management|journal=Med Mycol|year=2009|volume=47|issue=s1|pages=S324–S330|doi=10.1080/13693780802314809|pmid=19330659 |doi-access=free}}</ref> Prevalence of these diseases among the atopic population is 20-30 % and 6% in the general population. Allergic rhinitis, more commonly known as hay fever, is less frequently encountered in clinic compared to allergic fungal sinusitis. Differential diagnosis of allergic bronchopulmonary mycosis is difficult, and it is often misdiagnosed as tuberculosis, pneumonia, bronchiectasis, lung abscess or bronchial asthma.<ref>{{cite book|last=Maertens JA, Marr KA|title=Diagnosis of fungal infections|year=2007|publisher=Informa Healthcare|location=New York}}</ref>

Several serological tests can be performed to assess total IgE and allergen specific IgE and IgG: ELISA, MAST, HIA, and CAP RAST. However, more conventional allergy testing such as skin-prick tests can provide rapid results and are easy to conduct and inexpensive, though they may indicate false-positive or false-negative results.<ref>{{cite book|last=Maertens JA, Marr KA|title=Diagnosis of fungal infections|year=2007|publisher=Informa Healthcare|location=New York}}</ref> Current research has shown that there is an association between allergic fungal sinusitis and MHC II alleles,<ref>{{cite journal|last=Schubert MS|title=Allergic fungal sinusitis: pathophysiology, diagnosis and management|journal=Med Mycol|year=2009|volume=47|issue=s1|pages=S324–S330|doi=10.1080/13693780802314809|pmid=19330659 |doi-access=free}}</ref> suggesting a genetic component to this chronic inflammatory respiratory tract disorder. Treatment for allergic fungal sinusitis includes post-operative corticosteroid and aggressive anti-allergic inflammatory regimen including itraconazole or amphotericin B, while treatment for bronchopulmonary mycosis usually does not include surgery.<ref>{{cite journal|last=da Cunha|first=KC|author2=Sutton DA |author3=Fothergil AW |author4=Gene J |author5=Cano J |author6=Madrid H |author7=de Hoog S |author8=Crous PW |author9=Guarro J |title=In vitro antifungal susceptibility and molecular identity of 99 clinical isolates of the opportunistic fungal species Curvularia|journal=Diag Micr Infec Dis|year=2013|volume=76|issue=2 |pages=168–74|doi=10.1016/j.diagmicrobio.2013.02.034 |pmid=23558007 }}</ref><ref>{{cite journal|last=Schubert MS|title=Allergic fungal sinusitis: pathophysiology, diagnosis and management|journal=Med Mycol|year=2009|volume=47|issue=s1|pages=S324–S330|doi=10.1080/13693780802314809|pmid=19330659 |doi-access=free}}</ref>

==== Eye infection ==== Mycotic keratitis and conjunctivitis are more commonly reported in tropical climates. Environmental factors such as wind, temperature, rainfall and humidity have been found to influence the ecology of filamentous fungi. In the Gulf of Mexico for example, increased numbers of airborne spores of ''C. lunatus'' during hot, humid months has been linked to increased clinical reports of keratitis. ''C. lunatus'' commonly infects the cornea, and orbit of the eye, and infection can result from trauma, surgery or dissemination from paranasal sinuses. Endophthalmitis can result from deep fungal keratitis caused by ''C. lunatus'', where the Descemet's membrane is penetrated and compromised.<ref>{{cite book|last=Seal D, Pleyer U.|title=Ocular infection. 2nd ed|year=2007|publisher=Informa Healthcare|location=New York}}</ref>

In immunocompetent atopic individuals, 17% of those affected with allergic fungal sinusitis can develop orbital mycotic symptoms, where the fungus acts as an allergen causing allergic mucin. Pre-existing allergic fungal sinusitis, allergic conjunctivitis and use of soft contact lenses are risk factors for development of ophthalmomycosis.<ref>{{cite book|last=Seal D, Pleyer U.|title=Ocular infection. 2nd ed|year=2007|publisher=Informa Healthcare|location=New York}}</ref> Typical therapy includes administration of natamycin and azoles such as itraconazole, fluconazole, posaconazole and voriconazole.<ref>{{cite journal|last=da Cunha|first=KC|author2=Sutton DA |author3=Fothergill AW |author4=Gene J |author5=Cano J |author6=Madrid H |author7=de Hoog S |author8=Crous PW |author9=Guarro J |title=In vitro antifungal susceptibility and molecular identity of 99 clinical isolates of the opportunistic fungal species Curvularia|journal=Diag Micr Infec Dis|year=2013|volume=76|issue=2 |pages=168–74|doi=10.1016/j.diagmicrobio.2013.02.034 |pmid=23558007 }}</ref>

== References == {{Reflist }}

{{DEFAULTSORT:Cochliobolus Lunatus}} Category:Fungal plant pathogens and diseases Category:Cochliobolus Category:Fungi described in 1898 Category:Fungus species